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Biomedical subjects

Y Ren

Publications and source records attributed to Y Ren.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Correlation between the expression of vascular endothelial growth factor and prognosis of lung cancinoma].

OBJECTIVE: To determine the association between the expression of vascular endothelial growth factor (VEGF) and prognosis of lung cancer. METHODS: Apply the SP immunohistochemistry stain method to investigate the expression of VEGF in 60 specimens of patients with lung cancer, who had undergone curative resection more than 36 months before. RESULTS: The VEGF stain positive rate is 60% in 60 cases of lung cancer specimens; The immunoreactivity of VEGF was almost exclusively restricted to the tumor cells, the positive expression of VEGF showed significantly higher in the patients with lymph node metastasis and/or relapse. The positive rates of VEGF were higher in N1, N2 groups (53%, 80%) than in No group (23%, P < 0.01), and in relapse group (80%) than in non-relapse group (53%, P < 0.05). Postoperative survival time was shorter in VEGF(+) group (31 +/- 7 months) than in VEGF(-) group (64 +/- 7 months, P < 0.05). The 3, 5 year survival rates showed significant difference between VEGF(+) (31%, 11%) and VEGF(-) (88%, 50%) groups. CONCLUSIONS: The results suggest VEGF is a reliable prognostic parameter and antiangiogenesis therapy will be a useful strategy in treatment of the human lung cancer.

Adult↗
PubMed1999

[Histology and physiological function of dogs after extirpation of bronchi].

OBJECTIVE: To investigate the effect of extirpation of bronchi on histology and physiological function. METHODS: 21 dogs were divided in to two groups: control (3) and experimental (18). After bronchi extirpation one week, two weeks, one month, three months, six months, and twelve months, we used specimens to test the pulmonary surfactant (PS) and to observe the morphological changes. RESULTS: After the operation, the residual lung nearby the operative area had traumatic changes. Around the aforementioned area, the structure of lung was normal. Specially after six months, the lung returned to good status. We found that two weeks after operation, the contents of PS increased remarkably (P < 0.05). After one month the parameter returned to normal (P > 0.05). CONCLUSIONS: The residual lung after bronchi extirpation had ventilation and air-exchange functions. The lung function was preserved directly.

Animals↗
PubMed1999

[Establishment and identification of the monoepitopic monoclonal antibody of Plasmodium falciparum].

AIM: To prepare a monoepitopic monclonal antibody of Plasmoduim falciparum. METHODS: According to the theory of protein structure, a peptide with 6-9 residues representting the antigenicity of the original histidine-rich protein II (HRP-II) of P. falciparum was synthesized and used to immunize BALB/c mice after purity identification by capillary electrophoresis. RESULTS: Four hybridoma cell lines targeting a suitable peptide from pf HRP-II were obtained by using spleen embedment method and hybridoma technology. CONCLUSION: It is the first report to prepare a monoepitopic monoclonal antibody against original protein by selecting a suitable peptide from the primary sequence of protein.

Animals↗
PubMed1998

Cloning and characterization of GEF-H1, a microtubule-associated guanine nucleotide exchange factor for Rac and Rho GTPases.

The Rho-related small GTPases are critical elements involved in regulation of signal transduction cascades from extracellular stimuli to cell nucleus and cytoskeleton. The Dbl-like guanine nucleotide exchange factors (GEF) have been implicated in direct activation of these GTPases. Here we have identified a new member of the Dbl family, GEF-H1, by screening a human HeLa cell cDNA library. GEF-H1 encodes a 100-kDa protein containing the conserved structural array of a Dbl homology domain in tandem with a pleckstrin homology domain and is most closely related to the lfc oncogene, but additionally it contains a unique coiled-coil domain at the carboxyl terminus. Biochemical analysis reveals that GEF-H1 is capable of stimulating guanine nucleotide exchange of Rac and Rho but is inactive toward Cdc42, TC10, or Ras. Moreover, GEF-H1 binds to Rac and Rho proteins in both the GDP- and guanosine 5'-3-O-(thio)triphosphate-bound states without detectable affinity for Cdc42 or Ras. Immunofluorescence reveals that GEF-H1 colocalizes with microtubules through the carboxyl-terminal coiled-coil domain. Overexpression of GEF-H1 in COS-7 cells results in induction of membrane ruffles. These results suggest that GEF-H1 may have a direct role in activation of Rac and/or Rho and in bringing the activated GTPase to specific target sites such as microtubules.

3T3 Cells↗
PubMed1998

Dissociation of phagocyte recognition of cells undergoing apoptosis from other features of the apoptotic program.

Apoptosis is a programmed form of cell death characterized by biochemical and morphological changes affecting the nucleus, cytoplasm, and plasma membrane. These changes in various cellular compartments are widely regarded as mechanistically linked events in a single "program" in which activation of caspases and proteolysis of intracellular substrates represent a final common pathway leading to cell death. To date there has been very limited exploration of the linkage of this program to the plasma membrane changes, which bring about swift recognition, uptake, and safe degradation of apoptotic cells by phagocytes. Using the mitochondrial inhibitors antimycin A and oligomycin in human monocytic THP.1 cells triggered into apoptosis, we report the uncoupling of plasma membrane changes from other features of apoptosis. These inhibitors blocked increased plasma membrane permeability, externalization of phosphatidylserine, and recognition by two classes of phagocytes but not activation of caspase-3, cleavage of poly(ADP-ribose) polymerase and DNA fragmentation. Externalization of phosphatidylserine in apoptotic human leukemic U937 cells was also dissociated from caspase activation. Thus changes governing safe clearance of apoptotic cells may be regulated by an independent pathway to those bringing about caspase activation. This finding could have important consequences for attempts to manipulate cell death for therapeutic gain in vivo.

Amino Acid Chloromethyl Ketones↗
PubMed1998

The 58-kDa microspherule protein (MSP58), a nucleolar protein, interacts with nucleolar protein p120.

Protein p120 is a proliferation-related nucleolar protein which is detectable early in the G1 phase of the cell cycle and peaks early in the S phase. Most human malignant tumors contain much higher levels of protein p120 than normal resting cells. To identify p120-associated protein(s), a yeast two-hybrid screen was carried out using protein p120 as the bait. Two positive clones encoded portions of a novel protein, designated microspherule protein 58 kDa (MSP58). MSP58 mRNA is 1.9 kb and encodes an approximately 58-kDa polypeptide of 462 amino acids as shown by Western blotting of HeLa nucleolar proteins. The mouse MSP58 homolog has 97% amino acid similarity to human MSP58, but no MSP58 homolog was found in the yeast genome. The MSP58 N-terminal region contains serine-rich clusters and its C-terminal region has a coiled-coil domain. In insect Sf9 cells, recombinant p120 and MSP58 proteins associated with each other, confirming the results of the yeast two-hybrid assay. Deletion mutations revealed that the binding of MSP58 to p120 required a previously unrecognized coiled-coil domain within the N-terminal region of p120 and the C-terminal region of MSP58 protein. Immunofluorescence indicated that the MSP58 protein is localized in microspherules in the nucleolus. Anti-MSP58 Ig labeled nucleolar 'caps' when HeLa cells were treated with actinomycin D. When the MSP58 protein was overexpressed in COS-7 cells, the nucleolus became irregularly enlarged, which suggests that MSP58 may affect the size and shape of the nucleolus.

Amino Acid Sequence↗
PubMed1998

Nucleolar protein p120 contains an arginine-rich domain that binds to ribosomal RNA.

Human proliferation-associated protein p120 has previously been shown to localize to the nucleolus, and several functional domains of p120 have been elucidated. By using a nitrocellulose filter binding assay and a Northwestern blotting procedure this study shows that recombinant p120 binds to an rRNA fragment in vitro with a dissociation constant of 4 nM. The specific RNA-binding region of p120 (residues 1-57) was identified with glutathione S-transferase-fused p120 deletion constructs and Northwestern blotting procedures. This RNA-binding region of p120, which includes the nucleolar localization signal of p120, is similar to the arginine-rich RNA-binding regions found in other RNA-binding proteins such as HIV Rev and Tat. Experiments in vivo with HeLa cell nucleolar extracts showed that p120 was associated with the 60-80S pre-ribosomal particles. This association is disrupted by treatment with either RNase A or buffer of high ionic strength. These results suggest that p120 might be involved in rRNA/ribosome maturation, consistent with the role of the yeast homologue Nop2p in rRNA biogenesis.

Amino Acid Sequence↗
PubMed1998

Co-localization of the insulin receptor, jun protein and choline acetyltransferase in embryonic chick retina.

Previous work demonstrated that the availability of insulin to the embryonic chick retina at a critical developmental stage stimulated the activity of the acetylcholine synthetic enzyme, choline acetyltransferase (ChAT) and that this increase required the AP-1 transcription factor, c-jun. Here it is shown that immediately following a 2-5 min exposure to insulin there is, in the amacrine and ganglion cells of the chick embryo retina, a transient increase in the level of jun protein followed by a long-lasting increase in ChAT. These and previous results show that insulin receptor activation is necessary for the characteristic retina developmental increase in ChAT protein and that this increase is preceded by a transient increase in the synthesis of the transcription factor c-jun in the same retina cells. The data demonstrate an intracellular signal transduction pathway from the developmentally-activated insulin receptor through c-jun to ChAT and cholinergic differentiation.

Animals↗
PubMed1998

Structural characterization of two novel oxidative derivatives of cyclosporine generated by a chemical method.

OBJECTIVES: To study the generation of cyclosporine derivatives (CMs) by chemical oxidation of the parent compound using hydrogen peroxide. METHODS AND RESULTS: Hydrogen peroxide was added to cyclosporine (CsA), which was dissolved in ether. After liquid-liquid extraction, CMs were purified by high performance liquid chromatography (HPLC). Detailed structures of CMs were determined by fast atomic bombardment mass spectrometry (FABMS) and nuclear magnetic resonance spectroscopy (NMR). Our results indicated that the parent compound was modified at amino acid number 1 by hydroxylation of the carbon and the formation of a tetrahydrofuran five member ring structure. In addition, these two oxidative products of CsA were determined to be isomeric to each other, differing only in the configuration at one or more carbon atoms. This modification is in contrast to that observed for the formation of the cyclic metabolite of CsA, namely AM1c, by cytochrome P-450 isoenzymes, where the addition of the hydroxyl group occurs on the carbon of amino acid 1. CONCLUSION: 3 to 4 mg of 2 oxidative derivatives could be produced from 5 mg of CsA by chemical modification of the parent compound. In comparison, biotransformation using the drug-induced hepatic microsomal enzyme system could only produce 0.5 to 1 mg of metabolites/derivatives from 5 mg of CsA.

Chromatography, High Pressure Liquid↗
PubMed1998

Apoptosis: the importance of being eaten.

In vivo, cells undergoing apoptosis are usually recognised and swiftly ingested by macrophages or neighbouring cells acting as semi-professional phagocytes. This review debates evidence that the contents of apoptotic cells represent a danger to the organism, being capable of injuring tissue directly or triggering autoimmune responses, concluding that phagocytic clearance of intact apoptotic cells is a safe disposal route. Indeed, new data suggest that, in certain circumstances, phagocytes ingesting apoptotic cells may actively downregulate inflammatory and immune responses. Consequently, increasing evidence that there may be factors capable of perturbing safe clearance of apoptotic cells in vivo suggests that failure of this process may be a hitherto unrecognised pathogenetic factor in inflammatory and autoimmune diseases. New treatments designed to promote safe phagocytic clearance of dying cells can be anticipated, and it may even prove possible to eliminate unwanted cells by inducing appearance of cell surface 'eat me' signals.

Apoptosis↗
PubMed1998

Mutations within the cholecystokinin-B/gastrin receptor ligand 'pocket' interconvert the functions of nonpeptide agonists and antagonists.

We have reported previously that the transmembrane domains of the cholecystokinin-B/gastrin receptor (CCK-BR) comprise a putative ligand binding pocket. In the present study, we examined whether amino acid substitutions within the CCK-BR pocket altered the affinities and/or functional activities of L-365,260 (the prototypical nonpeptide CCK-BR antagonist) and two structural derivatives, YM022 (a higher affinity antagonist) and L-740,093S (a partial agonist). Eight amino acids that project into the CCK-BR pocket were individually replaced by alanine, using site-directed mutagenesis. Affinities for the nonpeptide molecules, as well as ligand-induced inositol phosphate production, were assessed with the wild-type and mutant receptors. For each of the nonpeptide ligands examined, a distinct series of mutations altered the affinity, suggesting that each ligand possessed a characteristic pattern of interactions within the CCK-BR pocket. Basal signaling levels and inositol phosphate formation induced by the full agonist CCK octapeptide were comparable for the wild-type receptor and all of the mutant CCK-BR forms. In contrast to the peptide agonist CCK octapeptide, the functional activities of the nonpeptide molecules were selectively altered by single point mutations within the CCK-BR pocket, resulting in interconversion of agonists and antagonists. These findings suggest that interactions between nonpeptide molecules and transmembrane domain amino acids of the CCK-BR can determine the functional activity and affinity of the ligands.

Animals↗
PubMed1998

Stimulation of the preprothyrotropin-releasing hormone gene by epidermal growth factor.

Regulation of the expression of the prepro-TRH (ppTRH) gene by epidermal growth factor (EGF) was investigated. The i.p. injection of EGF significantly stimulated hypothalamic ppTRH messenger RNA levels in rats. To clarify whether this stimulatory effect of EGF could be exerted at the level of gene transcription, the 5'-flanking region (-1893/+127) of the mouse ppTRH gene fused to a luciferase reporter gene was transiently transfected into pituitary GH4C1 cells, and the effect of EGF on gene transcription was measured by a luciferase assay. EGF stimulated ppTRH gene promoter activity in a time- and dose-dependent manner. Deletion analysis revealed that two different regions of the promoter, between -254 and -218 [EGF response element-1 (EGFRE1)] and between -130 and -84 (EGFRE2) were required for full stimulation by EGF. The two EGFREs possessed putative binding sequences for the transcription factor Sp1, and they functioned cooperatively in heterologous promoters. Nuclear extracts from GH4C1 cells specifically bound those two EGFREs in gel retardation assays. Two protein-DNA complexes were found on EGFRE1, whereas four complexes were observed on EGFRE2. Although the binding of nuclear extracts to EGFRE1 was competed for by the consensus Sp1 binding sequence, the complexes on EGFRE1 were not supershifted by an Sp1 antibody. Formation of the slower migrating protein complex on EGFRE1 was prevented by EDTA, suggesting that one of the EGFRE1-binding proteins might be an Sp1-related zinc finger protein. Competition and supershift experiments demonstrated that the EGFRE2-binding protein showing that the slowest migration possessed a characteristic similar to that of Sp1. Selective mutations of the Sp1-binding site in EGFRE2 markedly diminished the EGF-induced stimulation. These results suggest that EGF may function as a positive regulator of ppTRH gene expression, and that the stimulatory effect may be mediated through a cooperative interaction between Sp1 or Sp1-related proteins and additional factors that bind to two separate DNA regions.

Animals↗
PubMed1998

[Rescue and prevention of serious systemic toxicity following local anesthesia to mucous membranes of tetracaine].

Tetracaine remains a popular agent in clinical for the purpose of local anesthesia to mucous membranes. Its potential for systemic absorption and resulting toxicity has been seldom emphasized. One case of fatality from tetracaine pharyngeal local anesthesia for fibro-laryngoscopic procedure is described. The pharmacologic basis, clinical features, rescue and prevention for systemic toxicity is discussed.

Adolescent↗
PubMed1998

The puzzle of Wang Bing's life story.

Since Wang Bing made great contributions to the development of TCM, exploration on Wang Bing's life story is helpful to the analysis on the intention of his medical works. There are controversies on Wang's life story, some of which are still in debate. Through the elucidation of Wang's name, other names, sobriquet, dates of birth and death, official positons and scholarly lineage, this author holds that more relevant historical materials are needed so that the puzzle of his life story can be eventually revealed and uncovered.

China↗