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Biomedical subjects

Q Sun

Publications and source records attributed to Q Sun.

At least 145 records · Page 8Linked to original sources
PubMed1997

Calcium- and meiotic-spindle-independent activation of pig oocytes by the inhibition of staurosporine-sensitive protein kinases.

The dependence of pig oocyte activation (both nuclear activation and cortical granule exocytosis) induced by staurosporine on intracellular Ca2+ rise and spindle assembly was studied. Nuclear activation was evaluated by pronuclear (PN) formation, cleavage and their developmental ability, and cortical granule (CG) exocytosis was assessed by electron microscopy and laser confocal microscopy of oocytes labelled with fluorescein isothiocyanate-peanut agglutinin. Exposure of pig oocytes of 0.3 and 3 microM protein kinase inhibitor staurosporine for 30 min resulted in the nuclear activation in 71.8% and 85.7% of the oocytes, respectively. The pronuclei in activated oocytes contained several compact nucleoli. When the cleaved 2-cell oocytes were further cultured in vitro, 93.5% developed beyond the 4-cell stage, and 12.9% developed to the morula stage after 4 days of culture. Of the oocytes treated with 3 microM staurosporine, 62.5% and 9.4% released their CGs partially and completely, respectively. The nuclear activation induced by staurosporine was overcome by the prior treatment of oocytes with okadaic acid, resulting in only 33.3% of the oocytes undergoing nuclear activation. However, when oocytes were exposed first to 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (acetoxymethanal ester), a cell permeate calcium chelator, or Colcemid, a meiotic spindle disrupter, and then to staurosporine, nuclear activation was observed in 74.2% and 82.3% of the oocytes, respectively. These data were the same as those in oocytes treated only with staurosporine (85.7%). The present study indicates that pig oocytes can be activated by the inhibition of staurosporine-sensitive protein kinase(s), and that this activation is dependent upon mitogen-activated protein kinase but independent of the intracellular Ca2+ rise and spindle integrity.

Animals↗
PubMed1997

Effect of selenium on human phospholipid hydroperoxide glutathione peroxidase expression and host cell susceptibility to lipid hydroperoxide-mediated injury.

We recently isolated stable transfectants expressing human phospholipid hydroperoxide glutathione peroxidase (PHGPx) from the cells of guinea pig cell line 104C1 (Biochem. Biophys. Res. Commun. 219, 486-491, 1996). Among them, one transfectant, designated 104C1/O4C, expressed high glutathione peroxidase activity toward dilinoleoyl phosphatidylcholine hydroperoxide (PCOOH); and another one, 104C1/O2D, moderate activity. In the present study, we investigated the effect of selenium on the PHGPx activity and on the lipid hydroperoxide-mediated cell injury in the transfectants to clarify further the action of PHGPx in preventing oxidative injury of the cells. When transfectant 104C1/O2D cells were cultured in the medium added with 250 nM selenium, glutathione peroxidase activity toward PCOOH increased 8-fold. Western blot analysis also revealed an increase in the amount of protein immunoreactive against anti-rat PHGPx antibody in this transfectant. Lipid hydroperoxide-mediated cell injury to the transfectant 104C1/O2D was significantly suppressed in accordance with the increase in the enzyme activity when the cells were cultured in the medium added with selenium. On the contrary, neither glutathione peroxidase activity toward PCOOH nor susceptibility to the injury was affected by selenium addition to the medium of the parental 104C1 cells, which have no selenium-dependent glutathione peroxidase. These results clearly support our previous conclusion that expression of PHGPx is responsible for the protection of host cells from lipid hydroperoxide-mediated injury.

Animals↗
PubMed1997

Identification of D motif epitopes in Staphylococcus aureus fibronectin-binding protein for the production of antibody inhibitors of fibronectin binding.

A fibronectin-binding protein (FnBP) adhesin of Staphylococcus aureus possesses three 37- or 38-amino-acid motifs (D1, D2, and D3) that can each bind fibronectin (Fn) with low affinity and that in tandem comprise D1-3, a high-affinity Fn-binding domain. To identify epitopes for the generation of adhesion-blocking antibodies, rabbits were immunized with recombinant D1-3 or with a glutathione S-transferase fusion protein, GSTD1-3. Affinity-purified antibodies from the D1-3 immunization were poor inhibitors of Fn binding to S. aureus and recognized several different epitopes, with a preference for clusters of acidic amino acids that do not contribute to Fn binding. Antibodies generated with GSTD1-3 as an immunogen were more effective inhibitors, but concentrations in excess of 20 microg x ml-1 did not promote more than 50% inhibition. These antibodies were highly specific for amino acids 21 to 34 of D1 (D1(21-34)), which contain a sequence that is essential for Fn binding and are identical to D2 at 12 of 14 residues. Neither antibody preparation recognized D3(20-33) of the D3 motif, where the only homology to D1(21-34) and D2(21-34) comprises a sequence motif, GG(X3,4)(I/V)DF, that is critical to Fn binding. However, antibodies specific for both D1(21-34) and D3(20-33) could be obtained by using synthetic peptides corresponding to these sequences as immunogens. F(ab')2 fragments derived from these antibodies each caused 40 to 50% inhibition of Fn binding to S. aureus, and their ability to bind to purified FnBP was eliminated by competing Fn. However, mixtures of the two F(ab')2 preparations did not provide additive or synergistic inhibition of Fn binding. Therefore, inhibition of Fn binding to S. aureus requires antibodies specific for D1(21-34) and D3(20-33), but a mixture of antibodies specific for both sequences did not provide complete inhibition.

Adhesins, Bacterial↗
PubMed1997

Interactions between heterologous FtsA and FtsZ proteins at the FtsZ ring.

FtsZ and FtsA are essential for cell division in Escherichia coli and colocalize to the septal ring. One approach to determine what regions of FtsA and FtsZ are important for their interaction is to identify in vivo interactions between FtsA and FtsZ from different species. As a first step, the ftsA genes of Rhizobium meliloti and Agrobacterium tumefaciens were isolated and characterized. In addition, an FtsZ homolog that shared the unusual C-terminal extension of R. meliloti FtsZ1 was found in A. tumefaciens. In order to visualize their localization in cells, we tagged these proteins with green fluorescent protein (GFP). When R. meliloti FtsZ1-GFP or A. tumefaciens FtsZ-GFP was expressed at low levels in E. coli, they specifically localized only to the E. coli FtsZ ring, possibly by coassembly. When A. tumefaciens FtsA-GFP or R. meliloti FtsA-GFP was expressed in E. coli, they failed to localize detectably to the E. coli FtsZ ring. However, when R. meliloti FtsZ1 was coexpressed with them, fluorescence localized to a band at the midcell division site, strongly suggesting that FtsA from either A. tumefaciens or R. meliloti can bind directly to its cognate FtsZ. As expected, GFP-tagged FtsZ1 and FtsA from either R. meliloti or A. tumefaciens localized to the division site in A. tumefaciens cells. Therefore, the 61 amino acid changes between A. tumefaciens FtsA and R. meliloti FtsA do not prevent their direct interaction with FtsZ1 from either species, suggesting that those residues are not essential for protein-protein contacts. Moreover, the failure of the two non-E. coli FtsA derivatives to interact strongly with E. coli FtsZ in this in vivo system unless their cognate FtsZ was also present suggests that FtsA-FtsZ interactions have coevolved and that the residues which differ between the E. coli proteins and those of the two other species may be important for specific interactions.

Agrobacterium tumefaciens↗
PubMed1997

[Antagonistic effect of calcitonin gene related peptide on arrhythmia in rats].

Premature ventricular contraction (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF) were developed by endothelin-1 (ET-1) injected into the coronary ostia at the dose of 900 pmol/kg in anesthetized rats. No arrhythmia was elicited but blood pressure fell temporarily by calcitonin gene related peptide (CGRP), the injection into the coronary ostia. After pretreatment with CGRP incidence and severity of arrhythmia decreased at the same ET-1 dose. Arrhythmia score in CGRP 1200 pmol/kg + ET-1 group was lower than that in ET-1 group (P < 0.01). The results revealed that antiarrhythmic effect of CGRP may be partially brought about by its antagonistic effect against ET-1 induced arrhythmia.

Animals↗
PubMed1997

[Acute interstitial pneumonia: report of a case].

We report a case of acute interstitial pneumonia (AIP) determined by clinical appearance and pathologic manifestations. The patient was critically ill but survived by intensive treatment. The disease was characterized by fulminate onset and developed to respiratory failture. Its pathologic features as same as those of ARDS, but it is not differentiate AIP from chronic interstitial pneumonia on the basis of etiology. The outcome of AIP was improved by corticosteroid therapy. Relevant literature, history, pathogenesis, pathological features, clinical findings, differential diagnosis, treatment and prognosis of AIP are discussed.

Acute Disease↗
PubMed1997

[Experimental studies on somatic gene therapy for diabetes. I. Structuring of recombinant from human insulin gene and ammalian expression vector PRC/CMV].

To develop a model somatic gene therapy system for diabetes, we constructed a human insulin expression vector in non B cells. As the first step, an insulin cDNA fragment of 260 bp, generated by a complet digestion of PBCA with EcoR I and BamH I, was inserted into the EcoR I/BamH I site of plasmid PBS.SK by ligation of cohevise-ended DNA to construct transition plasmid PBS.INS. Then the plasmid PBS.INS was completly digested by Hind III and Xbal I. The small DNA fragment containing insulin cDNA gene was subcloned to the expression plasmid PRC/CMV to form recombinant PRC/CMV.INS.

DNA, Complementary↗
PubMed1997

[Clinical and pathological observation of recurrent nasal polyp formation].

To investigate the mechanism of nasal polyp recurrence, 19 patients with recurrent nasal polyp were retrospectively analysed. In 4 patients, nasal polyp specimens had been sent for pathological examination more than three times, and in 6 patients, bacteria culture was performed. There were two types of recurrent nasal polyp: water-cyst type (fast recurrence) and edematous granulation type (slow recurrence). Both types were the result of inflammatory reaction, perhaps related to trauma of operation. Water-cyst formation indicated stronger inflammatory reaction. During follow-up, 10 patients were cured and 9 recurred. Preventive measures against nasal polyp recurrence were discussed.

Adult↗
PubMed1997

Radioimmunoimaging of human breast cancer xenografts in nude mice by using human anti-human breast cancer monoclonal antibodies.

In this study, the human breast cancer-bearing nude mice model has been established and the radioimmunoimaging was carried out by using human anti-human monoclonal antibodies. The results showed that the breast tumor-bearing nude mice received 131I-McAb-CM-1 had a clear image of the xenograft during 4 to 6 days after injection and at the same time T/NT all over 1.0. The highest T/NT reached 7.1. It demonstrates that McAb-CM-1 can specially combine with breast cancer tissues and hopefully it could be used clinically to improve accurate rate of the early breast cancer diagnosis.

Animals↗
PubMed1997

[Expression of human betaIVS- II -nt 654 C --> T allele in HeLa cell].

OBJECTIVE: To establish a cell model expressing human betaIVS- II -nt 654C --> T allele (beta654 mutant). METHODS: DNA fragment of entire beta-globin gene encompassing the codon region and poly(A) signal of the allele was amplified by long PCR from the genomic DNA of a homozygote with beta65.4 mutation. The amplified fragments were cloned into the Hind III and Xba I sites of the pcDNA3.1 vector. After reidentification of the clone with beta654 mutant by DNA sequencing, the recombinant plasmid was transfected into HeLa cell using liposome method. The expression of the beta654 mutant gene in the transfected cells was detected by RT-PCR. RESULTS: Both the normally processed beta globin mRNA (183bp) and aberrant processed beta globin mRNA (256bp) were identified in the transfected HeLa cells, while no RT-PCR product was detected in the controls. CONCLUSION: The transfected HeLa cells can express human beta654 allele.

Alleles↗
PubMed1996

Regulation of cytokine production during development of autoimmune diabetes induced with multiple low doses of streptozotocin.

Cytokines have been shown to play an important role in regulating tolerance to islet Ags and provoking destructive islet lesions. However, data from a number of experimental systems have been conflicting, and the role of cytokines produced by T lymphocytes at various stages of diabetes has not been clearly defined. We have studied the production of cytokines in the pancreas during the development of autoimmune diabetes induced in mice by administration of (5) low doses of streptozotocin (STZ) (MDSDM). Diabetes in this model is T lymphocyte dependent. We used techniques of semiquantitative PCR to identify and quantitate cytokines that are produced. We have found that IL-2, IL-4, TNF-alpha, and IFN-gamma are expressed by the time the fourth dose of STZ is given. In the same pancreas, all of these cytokines (including IL-4) may be found. However, expression of IFN-gamma, but not IL-4, was limited to intrapancreatic lymphocytes and was not detectable at extrapancreatic lymphoid sites. Moreover, mAbs against IFN-gamma, but not against IL-4 or IL-2, prevent hyperglycemia and insulitis in MDSDM, suggesting that IFN-gamma regulates development of disease. Cells in the pancreases of nondiabetic mice treated with anti-IFN-gamma mAb and STZ show enhanced expression of IL-4, but the prevention of disease is due to blockade of the IFN-gamma itself, and not due to secretion of IL-4, because systemic administration of IL-4 does not prevent MDSDM. Thus, our findings indicate that cytokines produced by Th1 (or T cytolytic 1) and Th2 (or T cytolytic 2) cells are found in the pancreases of mice developing autoimmune diabetes. IFN-gamma is responsible for progression to diabetes, and its production is limited to lymphocytes only at that site.

Animals↗
PubMed1996

Characterization of human leucocytes bearing the IL-3 receptor.

Human leucocytes from peripheral blood and tonsil were examined for the presence of the IL-3 receptor using monoclonal antibodies directed to epitopes of the alpha and beta chains of the receptor. We found that the beta chain, common to IL-3, IL-5, and GM-CSF, was either present at low levels or not detected on the majority of peripheral blood and tonsil B lymphocytes, while the alpha chain showed a distinct but restricted distribution. In peripheral blood the IL-3R alpha chain was limited to a subpopulation of peripheral B lymphocytes and a population of cells which lack lineage-specific markers. Dimly staining cells were identified as B lymphocytes as they coexpressed CD19, CD20, CD22, CD24, and HLA-DR. A brightly staining population lacks T and B lymphocyte, NK specific, and macrophage lineage markers but expresses CD9, CD45RO, CD26, and, in a proportion of cells, CD36 and CD60. This population remains unclassified. In tonsil tissue IL-3R alpha chain expression was strongest on B lymphocytes present in the T cell rich areas of tonsillar tissue. The IL-3R alpha bearing B tonsil cells included cells in both CD23 and IgD positive and negative populations. The phenotype of the IL-3R alpha positive B cells defines them as a population of B lymphocytes distinct from previously characterized cells in the lymphoid architecture. Lymphoblastoid cell lines with a corresponding phenotype were also identified.

Antigens, CD↗
PubMed1996

Expression of human phospholipid hydroperoxide glutathione peroxidase gene for protection of host cells from lipid hydroperoxide-mediated injury.

A cDNA encoding human phospholipid hydroperoxide glutathione peroxidase (PHGPx) was obtained by PCR amplification from human testis cDNA and was inserted into the plasmid pRc/CMV to construct an expression vector for human PHGPx. Guinea pig cell line 104C1 cells were transfected with the expression vector. One of the transfectants, designated 104Cl/O4C, expressed high glutathione peroxidase activity toward dilinoleoyl phosphatidylcholine hydroperoxide and linoleic acid hydroperoxide. Western blot analysis revealed a large amount of protein immunoreactive against anti-PHGPx antibody in the transfectant. When the cells were incubated with these hydroperoxides, the parental cells suffered from serious cell injury, whereas the transfectant was extremely resistant against lipid hydroperoxide-mediated injury.

Animals↗
PubMed1996

Monoclonal antibody 7G3 recognizes the N-terminal domain of the human interleukin-3 (IL-3) receptor alpha-chain and functions as a specific IL-3 receptor antagonist.

The human interleukin-3 receptor (IL-3R) is expressed on myeloid, lymphoid, and vascular endothelial cells, where it transduces IL-3-dependent signals leading to cell activation. Although IL-3R activation may play a role in hematopoiesis and immunity, its aberrant expression or excessive stimulation may contribute to pathologic conditions such as leukemia, lymphoma, and allergic reactions. We describe here the generation and characterization of a monoclonal antibody (MoAb), 7G3, which specifically binds to the IL-3R alpha-chain and completely abolishes its function. MoAb 7G3 immunoprecipitated and recognized in Western blots the IL-3R alpha-chain expressed by transfected cells and bound to primary cells expressing IL-3R alpha. MoAb 7G3 bound the IL-3R alpha-chain with a kd of 900 pmol/L and inhibited 125I-IL-3 binding to high- and low-affinity receptors in a dose-dependent manner. Conversely, IL-3 but not granulocyte-macrophage colony-stimulating factor (GM-CSF) inhibited 125I-7G3 binding to high- and low-affinity IL-3Rs, indicating that MoAb 7G3 and IL-3 bind to common or adjacent sites. In keeping with the inhibition of IL-3 binding, MoAb 7G3 antagonized IL-3 biologic activities, namely stimulation of TF-1 cell proliferation, basophil histamine release, and IL-6 and IL-8 secretion from human endothelial cells. Two other anti-IL-3R alpha-chain MoAbs failed to inhibit IL-3 binding or function. Epitope mapping experiments using truncated IL-3R alpha-chain mutants and IL-3R alpha/GM-CSFR alpha chimeras revealed that 31 amino acids in the N-terminus of IL-3R alpha were required for MoAb 7G3 binding. MoAb 7G3 may be of clinical significance for antagonizing IL-3 in pathologic conditions such as some myeloid leukemias, follicular B-cell lymphoma, and allergy. Furthermore, these results implicate the N-terminal domain of IL-3R alpha in IL-3 binding. Since this domain is unique to the IL-3/GM-CSF/IL-5 receptor subfamily, it may represent a novel and common binding feature in these receptors.

Animals↗
PubMed1996

Oxytocin and vasopressin mRNA expression in rat hypothalamus following kainic acid-induced seizures.

In this study, the regulation of hypothalamic oxytocin and vasopressin messenger RNA expression following the induction of seizures was investigated by in situ hybridization. Following kainic acid-induced seizures, a significant increase in oxytocin messenger RNA in the paraventricular nucleus was demonstrated at 1.5 h, one and two weeks; its level decreased at three weeks and was significantly increased again at four weeks; at eight weeks the messenger RNA level still remained higher than that of controls. Vasopressin messenger RNA in the paraventricular nucleus was increased significantly only at 1.5 h following induction of seizures. The oxytocin messenger RNA level in the supraoptic nucleus was also increased early at 1.5 h and later at four weeks following seizures; however, these increases did not last as long as those in the paraventricular nucleus. Vasopressin messenger RNA in the supraoptic nucleus was also increased after the initial seizures; however, its messenger RNA level vacillated up and down throughout the post-seizure times studied. The earliest significant increase of vasopressin messenger RNA was at one week after seizures, and there was a late significant increase of vasopressin messenger RNA at three weeks after seizures. The present study demonstrates that following kainic acid-induced seizures both, the oxytocin and vasopressin messenger RNA expressions, were up-regulated and these up-regulations were long-term events. The increase of oxytocin messenger RNA in the paraventricular nucleus was more persistent than the others. The pattern of messenger RNA up-regulation was different for oxytocin and vasopressin, and different in the paraventricular nucleus and supraoptic nucleus. These different patterns of messenger RNA elevations suggest that the different components of the rat hypothalamus were regulated differentially by kainic acid-induced seizures.

Animals↗