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Biomedical subjects

X Cui

Publications and source records attributed to X Cui.

At least 55 records · Page 3Linked to original sources
PubMed1997

Promoter analysis of the rat beta1-adrenergic receptor gene identifies sequences involved in basal expression.

The beta1-adrenergic receptor (beta1-AR) mediates several functions of catecholamines in the heart, including the stimulation of heart rate and contractility. The expression of the rat beta1-AR gene was assessed by transiently transfecting chimeric genes containing the beta1-AR promoter, driving the luciferase reporter gene into various cell lines. beta1-AR/luciferase vectors containing 3 kb of the 5'-flanking region and extending to -126 relative to the start site of translation were expressed at high levels in ventricular myocytes, SK-N-MC cells, and HepG2 cells. The addition of 26 nucleotides from -125 to -100 to the -3311 beta1-AR/luciferase chimeric gene reduced expression in myocytes and SK-N-MC cells while eliminating expression in HepG2 cells. This element is located 125 base-pairs 3' to the transcriptional start site. The mutation of four nucleotides between -121 and -118 diminished the inhibitory effect of this element. The inhibitory activity of the -125 to -100 sequence was completely dependent on promoter context and positioning. In addition to this 3' element, sequences between -3311 and -2740 in the 5'-flanking region of the beta1-AR gene were required for the full transcriptional suppression. Using DNase I footprinting and gel mobility assays, it was determined that within the 26-bp region, rat heart nuclear proteins bound to two sites between nucleotides -123 and -112 and -106 and -100. Therefore, appropriate basal expression of the beta1-AR gene involves widely separated sequences 3' and 5' to the transcriptional start site.

Animals↗
PubMed1997

[Studies on cell senescence induced by D-galactose in cultured neurons and fibroblasts].

The cell senescence induced by D-galactose (D-gal) in cultured rat fetal brain neurons and human fetal lung fibroblast was investigated in vivo and in vitro. The results showed pronounced decreases in nerve cell diameters, number of process and percentage of multiprocess neurons including "pyramidal" and "stellate" shaped and a rather high level of mortality rate observed in D-gal-treated (8 g/L) neurons. Lessening of the proliferating population of lung fibroblast taken from rat treated with D-gal (50 mg/kg.d, subcutanous injection for 6 weeks) was observed. We have also determined the changes of cell cycle in human fetal lung fibroblast cells treated with D-gal (8 g/L): the proportion of the G0-G1 cells increased but the G2-M and DNA level and the results showed that decreased and the cell growth rate declined in comparison with those of the control. Lipid peroxidation was observed in both kinds of cells because D-gal was proved to have action of decreasing SOD activity and increasing MDA content, the results found in D-gal-treated rats were similar to those observed in hypoxanthine-xanthine oxidation reaction system (O2-), indicating that reactive oxygen was generated in the course of D-gal metabolism. It is concluded that D-gal has the hastening effect on cell senescence and oxidative stress might be responsible for this aging effect.

Aging↗
PubMed1997

[A simple nitric oxide exposure system for small animals].

A nitric oxide exposing system was designed for experimental research, which consist of equipments such as plexiglass chamber, blower, flowmeter, NO/N2 cylinder, pure O2 cylinder, NOx analyzer, and O2/CO2 monitor. The efficacy of the whole system has been verified through our practice as shown by the following results: measured NO inside the chamber were close to designed NO concentration, measured O2 concentrations in the chamber were similar to that of the atmosphere, and the highest nitrogen dioxide (NO2) and carbon dioxide (CO2) concentrations were lower than 3 ppm and 0.3% respectively. The experimental facility is simple in construction, easy to be operated and convenient for research on effects and toxicity of long-term inhaled nitric oxide in small animals.

Administration, Inhalation↗
PubMed1997

[Effect of cigarette smoking on lipid peroxidation and antioxidation in rat lens].

The effects of cigarette smoking on lipid peroxidation, the activities of antioxidases, and the level of non-protein sulphydryl group in the rat lenses were investigated. The results showed that compared with the control group, MDA contents were significantly higher, while the wet weight of lenses, the concentration of non-protein sulphydryl group, the activities of superoxide dismutase and glutathione peroxidase were significantly decreased in the smoking rats. This study suggested that cigarette smoking might be involved in the development of cataract.

Animals↗
PubMed1997

[Observation on human embryonic lung fibroblast proliferation mediated by mitogen activated protein kinase].

OBJECTIVE: To study the effect of mitogen activated protein kinase (MAPK) on the proliferation of human embryonic lung fibroblast (HELF) induced by 60Co irradiation and the relationship between MAPK and angiotensin II (A II). METHODS: Cell proliferation was measured with enzyme-labeling method; angiotensin II, MAPK and type I precollagen synthesis as well as the role of sodium nitroprusside on the inhibition of A II were evaluated adopting immunohistochemical technique combined with image analysis after 1-5 Gy 60Co gamma-ray irradiation on the cultured HELF. RESULTS: Irradiation at 1-5 Gy promoted cell proliferation and type I precollagen synthesis; the syntheses of A II and MAPK were also increased in the irradiated cells. Exogenous A II enhanced cell proliferation, but sodium nitroprusside inhibited the action of A II. CONCLUSIONS: HELF proliferation induced by 60Co irradiation is a chain reactive course, in which, A II and MAPK are involved. MAPK may play a role of limiting valve in the signal transduction of cellular proliferation.

Angiotensin II↗
PubMed1996

The gene encoding LERK-7 (EPLG7, Epl7), a ligand for the Eph-related receptor tyrosine kinases, maps to human chromosome 5 at band q21 and to mouse chromosome 17.

The eph-related receptors are the largest subfamily of receptor tyrosine kinases. Recently, we and others have identified seven different, but related, cDNAs encoding membrane-bound ligands for this family of receptors. One member, LERK-7, is attached to the cell membrane via glycosyl-phosphatidylinositol linkage and has been found to be a ligand for the eph-family receptors hek, elk, eck, and rek. Using PCR-based screening of human x rodent somatic cell hybrid DNAs, we have assigned the gene that encodes LERK-7 (EPLG7) to human chromosome 5. Fluorescence in situ hybridization to metaphase chromosome preparations using a genomic clone from the locus refined this localization to chromosome 5, band q21. In addition, Southern blot analysis of DNAs from interspecific backcross mice indicated that the mouse homologue Epl7 maps to a homologous region on chromosome 17.

Animals↗
PubMed1996

The rf2 nuclear restorer gene of male-sterile T-cytoplasm maize.

The T cytoplasm of maize serves as a model for the nuclear restoration of cytoplasmic male sterility. The rf2 gene, one of two nuclear genes required for fertility restoration in male-sterile T-cytoplasm (cmsT) maize, was cloned. The protein predicted by the rf2 sequence is a putative aldehyde dehydrogenase, which suggests several mechanisms that might explain Rf2-mediated fertility restoration in cmsT maize. Aldehyde dehydrogenase may be involved in the detoxification of acetaldehyde produced by ethanolic fermentation during pollen development, may play a role in energy metabolism, or may interact with URF13, the mitochondrial protein associated with male sterility in cmsT maize.

Acetaldehyde↗
PubMed1996

A [2Fe-2S] protein encoded by an open reading frame upstream of the Escherichia coli bacterioferritin gene.

An open reading frame located upstream of the bacterioferritin gene in Escherichia coli encodes a hypothetical 64-residue protein [Andrews, S.C., Harrison, P.C., & Guest, J.R. (1989) J. Bacteriol. 171, 3940-3947)]. The spacing of the four cysteine residues in this hypothetical protein is identical to that in a region of NIFU, a [2Fe-2S] protein found in nitrogen-fixing bacteria [Fu, W., Jack, R.F., Morgan, T.V., Dean, D.R., & Johnson, M.K. (1994) Biochemistry 33, 13455-13463)]. The NIFU-like E. coli gene was cloned and overexpressed with a C-terminal "His tag" in E. coli using the T7 RNA polymerase/promoter system, and the protein was purified by metal-chelate affinity chromatography. UV-vis absorption and EPR spectra together with iron and amino acid analyses conclusively established that this NIFU-like E. coli protein contains one [2Fe-2S] cluster which can exist in at least two oxidation levels: +2 for the as-purified protein, and +1 for dithionite-reduced protein. Size-exclusion chromatography established that this His-tagged [2Fe-2S] protein is monomeric in solution. Affinity chromatography demonstrated specific complex formation between bacterioferritin (Bfr) and this NIFU-like [2Fe-2S] protein, which is dubbed Bfd. An open reading frame encoding a homologous Bfd is located near a Bfr gene in at least one other bacterium. Bfd may, therefore, constitute a general redox and/or regulatory component participating in the iron storage or mobilization functions of Bfr.

Amino Acid Sequence↗
PubMed1996

C-Fos proteins are not involved in the activation of preproenkephalin gene expression in rat brain by peripheral electric stimulation (electroacupuncture).

The present work was designed to study the role of the oncogene product c-Fos in activating the transcription of preproenkephalin (PPE) gene following a kind of peripheral electric stimulation known as electroacupuncture (EA) stimulation. The temporal patterns of rat brain c-fos and PPE mRNA expression were evaluated using the method of Northern blotting, showing that c-fos mRNA expression, which peaked at 2 h after the termination of EA, was always ahead of the PPE mRNA expression which began at 4 h and peaked at 48 h after EA. The methods of immunocytochemistry (ICC) and in situ hybridization (ISH) techniques were combined to identify the co-existence of c-Fos protein and PPE mRNA at the cellular level. The results showed that only a small percentage of PPE mRNA-containing neurons depicts Fos-like immunoreactive nuclei. These findings suggest that c-Fos protein may not be involved in the activation of brain PPE gene transcription induced by peripheral electric stimulation.

Animals↗
PubMed1996

Multiplex genotype determination at a large number of gene loci.

To facilitate large-scale genotype analysis, an efficient PCR-based multiplex approach has been developed. For simultaneously amplifying the target sequences at a large number of genetic loci, locus-specific primers containing 5' universal tails are used. Attaching the universal tails to the target sequences in the initial PCR steps allows replacement of all specific primers with a pair of primers identical to the universal tails and converts the multiplex amplification into "uniplex." Simultaneous amplification of 26 genetic loci with this approach is described. The multiplex amplification can be coupled with genotype determination. By incorporating a single-base mismatch between a primer and the template into the target sequences, a polymorphic site can be converted into a desirable restriction fragment length polymorphism when it is necessary. In this way, the allelic PCR products for the polymorphic loci can be discriminated by gel electrophoresis after restriction enzyme digestion. In this study, 32 loci were typed in such a multiplex way.

Alleles↗
PubMed1996

Ascaris, people and pigs in a rural community of Jiangxi Province, China.

A longitudinal investigation on natural populations of Ascaris in humans and pigs and an investigation of soil contamination with Ascaris eggs were carried out from June 1993 to June 1994 in 2 villages, Manhu area, Xinjian County, Jiangxi Province, China. Results from these studies indicate that although human ascariasis is endemic there is significant fluctuation in both prevalence and the mean number of eggs/g faeces (epg) of the communities. Fluctuation of age-stratified prevalence and mean epg was detected in children but not in most adult groups. Most cases of human ascariasis were judged to involve low intensities of infection and a typical overdispersion distribution pattern was observed through the year. It was estimated that during the year, nearly half of the eggs discharged in the environment came from infections in children aged between 2 and 15 years which accounted for about 30% of the total population. Soil in and around houses and in vegetable gardens was found to be contaminated by Ascaris eggs and this situation remained relatively stable throughout the year. Monthly developmental rate of Ascaris eggs in soil was detected and the results suggest that the fluctuation in prevalence observed during the year should be directly attributed to the effect of seasonality of egg development. Features of Ascaris infection in pigs were found to be similar to those in humans except for a lower mean intensity of infection. The possibility of cross-infection of Ascaris between human and pig hosts is discussed.

Adolescent↗
PubMed1996

Helix-loop-helix proteins LYL1 and E2a form heterodimeric complexes with distinctive DNA-binding properties in hematolymphoid cells.

LYL1 is a basic helix-loop-helix (HLH) protein that was originally discovered because of its translocation into the beta T-cell receptor locus in an acute lymphoblastic leukemia. LYL1 is expressed in many hematolymphoid cells, with the notable exceptions of thymocytes and T cells. Using the yeast two-hybrid system to screen a cDNA library constructed from B cells, we identified the E-box-binding proteins E12 and E47 as potential lymphoid dimerization partners for LYL1. The interaction of LYL1 with E2a proteins was further characterized in vitro and shown to require the HLH motifs of both proteins. Immunoprecipitation analyses showed that in T-ALL and other cell lines, endogenous LYL1 exists in a complex with E2a proteins. A preferred DNA-binding sequence, 5'-AACAGATG(T/g)T-3', for the LYL1-E2a heterodimer was determined by PCR-assisted site selection. Endogenous protein complexes containing both LYL1 and E2a bound this sequence in various LYL1-expressing cell lines and could distinguish between the LYL1 consensus and muE2 sites. These data demonstrate that E2a proteins serve as dimerization partners for the basic HLH protein LYL1 to form complexes with distinctive DNA-binding properties and support the hypothesis that the leukemic properties of the LYL1 and TAL subfamily of HLH proteins could be mediated by recognition of a common set of target genes as heterodimeric complexes with class I HLH proteins.

Animals↗
PubMed1996

Identification of a glucocorticoid repressor domain in the rat beta 1-adrenergic receptor gene.

The expression of the gene encoding the rat beta 1-adrenergic receptor is suppressed by glucocorticoids (Kiely et al., 1994). Within the 3.2-kb 5'-flanking region of the promoter, two potential glucocorticoid response elements (GREs) at -950 and -2791 relative to the translational ATG were identified. Characterization of the glucocorticoid-responsive sequences in the 5'-flanking region of the beta 1-adrenergic receptor gene was explored in rat C6 glioma cells and human HepG2 hepatoma cells using transient expression of beta 1-adrenergic receptor-luciferase fusion genes. The ability of glucocorticoids to suppress luciferase expression was not altered when the most 5'-localized GRE was deleted. Deleting the potential GRE at -950, in contrast, abolished glucocorticoid-induced suppression of the beta 1-adrenergic receptor-luciferase gene transcription. A 25-bp element containing the GRE sequence between nucleotides -950 and -926 confers glucocorticoid-dependent inhibition of transcription to a neutral promoter. Gel mobility shift assays with the alpha-subunit of the human glucocorticoid receptor (hGR alpha) expressed in reticulocyte lysates demonstrated specific binding to the 25-bp sequence harboring the putative GRE. We report an inhibitory GRE in the promoter of the rat beta 1-adrenergic receptor gene that is conserved among the rat, human, and mouse genes.

Animals↗
PubMed1996

[The laboratory study on biofragmentable anastomosis rings (BAR) in gastrointestinal tract reconstruction].

To study and investigate the feasibility of biofragmentable anastomosis ring (BAR) for gastrointestinal (GI) tract reconstruction, we performed gastroenterostomy in 34 dogs. BAR anastomoses were performed with proper outer diameter and gape size in small bowel in 8 cases, in large bowel in 11 cases, in esophagus in 12 cases, in esophago-intestinal in 2 cases, in gastrojejunum in 1 cases. The postoperative serial X-ray examinations showed that BAR maintained good integration two weeks postoperation. The ring disintegrated into several small fragments that passed out of the body in feces from the 14th postoperative day after surgery. All of the dogs were killed on the 28th operative day and autopsied. The anastomosis site had smooth serosa and scar membrane in gross and were substituted by regenerative fibrous tissue. The specimen barim-air double contrast X-ray revealed that GI tract was coherent without leakage and stenosis. Therefor, the authors recognized that BAR can be recommended as a safe technique in GI operation.

Anastomosis, Surgical↗
PubMed1996

[Detection of konjac glucomannan in seven Amorphophallus Blume species].

Seven Amorphophallus species were detected for konjac glucomananam (KGM). It has been found out that A. albus, A. konjac, A. yuloensis, A. xemengensis and A. dunnii are of higher contents of KGM (30%), but A. sinensis and A. yunnanensis are not as further comfirmed by TLC analysis. It follows that A. albus, A. konjac, A. yuloensis, A. xemengensis and A. dunnii are high quality resources of KGM, but A. sinensis and A. yunanensis cannot be used as substitutes for the above-cited five species.

Chromatography, Thin Layer↗
PubMed1995

Novel proteins of the phosphotransferase system encoded within the rpoN operon of Escherichia coli. Enzyme IIANtr affects growth on organic nitrogen and the conditional lethality of an erats mutant.

Two rpoN-linked delta Tn10-kan insertions suppress the conditionally lethal erats allele. One truncates rpoN while the second disrupts another gene (ptsN) in the rpoN operon and does not affect classical nitrogen regulation. Neither alter expression of era indicating that suppression is post-translational. Plasmid clones of ptsN prevent suppression by either disruption mutation indicating that this gene is important for lethality caused by erats. rpoN and six neighboring genes were sequenced and compared with sequences in the database. Two of these genes encode proteins homologous to Enzyme IIAFru and HPr of the phosphoenolpyruvate:sugar phosphotransferase system. We designate these proteins IIANtr (ptsN) and NPr (npr). Purified IIANtr and NPr exchange phosphate appropriately with Enzyme I, HPr, and Enzyme IIA proteins of the phosphoenolpyruvate: sugar phosphotransferase system. Several sugars and tricarboxylic acid cycle intermediates inhibited growth of the ptsN disruption mutant on medium containing an amino acid or nucleoside base as a combined source of nitrogen, carbon, and energy. This growth inhibition was relieved by supplying the ptsN gene or ammonium salts but was not aleviated by altering levels of exogenously supplied cAMP. These results support our previous proposal of a novel mechanism linking carbon and nitrogen assimilation and relates IIANtr to the unknown process regulated by the essential GTPase Era.

Amino Acid Sequence↗