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Biomedical subjects

M X Ding

Publications and source records attributed to M X Ding.

At least 19 recordsLinked to original sources
PubMed2006

Olaquindox and cyadox stimulate growth and decrease intestinal mucosal immunity of piglets orally inoculated with Escherichia coli.

One hundred and fifty piglets were randomly allotted to one of six treatments to determine the effects of olaquindox and cyadox on growth and intestinal immune response including the number of intraepithelial lymphocytes and immunoglobulin A secreting cells (ASCs) during the three-week period. A 2 x 3 factorial arrangement of treatments was employed with the following factors: (1) Escherichia coli (O(139):K(88), 10(10) CFU) inoculation or control and (2) no antimicrobials, 100 mg/kg olaquindox and 100 mg/kg cyadox in the basal diet respectively. The antimicrobial supplementations improved (p < 0.01) average daily gain and feed conversion ratio (FCR) during the experiment. Average daily gain and FCR in the cyadox-supplemented pigs were higher (p < 0.05) than those in the olaquindox-supplemented pigs. Intraepithelial lymphocytes and ASCs decreased (p < 0.05) when the diets were supplemented. Jejunal ASCs in the cyadox-supplemented pigs were lower (p < 0.05) than those in the olaquindox-supplemented pigs. Olaquindox and cyadox suppressed E. coli-induced intestinal immune activation, which may be involved in the observed growth promotion.

Animal Feed↗
PubMed2006

Effects of cyadox and olaquindox on intestinal mucosal immunity and on fecal shedding of Escherichia coli in piglets.

A 2 x 3 factorial arrangement of treatments was used to determine the effects of olaquindox and cyadox on the intestinal mucosal immune response and on fecal shedding of Escherichia coli in Landrace x Large White barrows that had been orally given 10(10) cfu of E. coli (O139:K88). Factors included 1) E. coli inoculation or no inoculation, and 2) no antimicrobial, 100 mg of olaquindox/kg, and 100 mg of cyadox/kg in the basal diet, respectively. The effects of cyadox and olaquindox were assessed in terms of fecal shedding of E. coli, the number of intraepithelial lymphocytes (IEL), immunoglobulin A-positive cells (APC) in the intestinal lamina propria, and ADG. There was no difference in the fecal shedding of total E. coli or the inoculated E. coli between olaquindox-supplemented pigs and cyadox-supplemented pigs during the experiment. However, fecal shedding of the inoculated E. coli in olaquindox- or cyadox-supplemented pigs was less (P < 0.05) than that in nonsupplemented pigs. Escherichia coli inoculation increased IEL and APC in the jejunum and ileum, but olaquindox or cyadox decreased IEL and APC (P < 0.05). Jejunal APC in cyadox-supplemented pigs was less (P < 0.05) than that in olaquindox-supplemented pigs. Escherichia coli inoculation reduced (P < 0.05) ADG, whereas the supplementations improved ADG (P < 0.01) during the experiment. Average daily gain in cyadox-supplemented pigs was greater (P < 0.05) than that in olaquindox-supplemented pigs. The data indicated that olaquindox and cyadox reduced the number of intestinal E. coli and suppressed E. coli-induced immune activation, which might be responsible for the enhanced growth that was observed.

Animals↗
PubMed2001

Altered expression of nuclear matrix proteins in etoposide induced apoptosis in HL-60 cells.

The events of cell death and the expression of nuclear matrix protein (NMP) have been investigated in a promyelocytic leukemic cell line HL-60 induced with etoposide. By means of TUNEL assay, the nuclei displayed a characteristic morphology change, and the amount of apoptotic cells increased early and reached maximun about 39% after treatment with etoposide for 2 h. Nucleosomal DNA fragmentation was observed after treatment for 4 h. The morphological change of HL-60 cells, thus, occurred earlier than the appearance of DNA ladder. Total nuclear matrix proteins were analyzed by 2-dimensional gel electrophoresis. Differential expression of 59 nuclear matrix proteins was found in 4 h etoposide treated cells. Western blotting was then performed on three nuclear matrix acssociated proteins, PML, HSC70 and NuMA. The expression of the suppressor PML protein and heat shock protein HSC70 were significantly upregulated after etoposide treatment, while NuMA, a nuclear mitotic apparatus protein, was down regulated. These results demonstrate that significant biochemical alterations in nuclear matrix proteins take place during the apoptotic process.

Antigens, Nuclear↗
PubMed1998

A study on the relationship between antisense EGFR cDNA fragments and nuclear matrix proteins in glioblastoma cells.

The association of antisense epidermal growth factor receptor (EGFR) cDNA fragments with nuclear matrix from EGFR-antisense transfected glioblastoma cell lines U343 and U87 was investigated. A 1015 bp DNA fragment (primer I-II) was amplified in both genomic DNA and nuclear matrix-associated DNA (NM DNA) from EGFR-antisense transfected glioblastoma cell lines U343E and U87E. Two different DNA fragments (940 bp and 110 bp) were amplified by primer I-III in both genomic DNA and NM DNA of U343E, while one 110 bp PCR product was shown with the same primer in both genomic DNA and NM DNA of U87E only. After EGFR-antisense transfection, the binding property of the 110 bp DNA fragment (primer IV-V) to nuclear matrix was not affected. Southwestern blotting demonstrated the presence of antisense EGFR cDNA binding nuclear matrix proteins. Our findings demonstrate that not only EGFR DNA is associated with nuclear matrix, but the transfected antisense EGFR cDNA also binds to nuclear matrix proteins. The nuclear matrix is most likely involved in the replication and transcription of antisense EGFR cDNA or hybridisation with sense mRNA in vitro.

Brain Neoplasms↗
PubMed1998

[The relationship between protein synthesis of Sindbis virus and host cytoskeletons].

In our experiments, protein synthesis of host cells were inhibited quickly at the early stage of infection by Sindbis virus. Polysome and mRNA of host cell fell off from cytoskeletons, whereas virus RNA bound up. We also found it was via 3'-terminal that virus RNA bound with cytoskeleton. After studying on the virus nonstructural proteins, we found the synthesis and processing of virus protein in vitro were far slowly than in vivo, and most of proteins were premature. So, the cytoskeletons may play an important role there. After treated with colchicine and cytochalasin B, the microtubule and microfilament were destroyed. However, the synthesis and processing of nonstructural proteins of Sindbis virus didn't change much, while the structural proteins were inhibited largely. These results showed the differences of dependence of the synthesis of the two kinds of proteins on cytoskeletons. Microtubule and microfilament may be more important to the synthesis of structural proteins than to that of the nonstructural proteins.

Actins↗
PubMed1995

[Evidence that uroplakins exist in the intermediate cell of mouse bladder epithelium].

Asymmetric unit membrane (AUM) consisting of uroplakins is a remarkable structure in the apical plasma membrane of mammalian urothelium. The present study demonstrated that uroplakins existed in intermediate cells of mouse bladder epithelium and formed the typical AUM only in fusiform vesicles of the intermediate cells. The fusiform vesicle is also associated tightly with intermediate filament much like in those of superficial cells. This presents a reliable evidence for the morphogenesis of AUM and the differentiation model of bladder urothelium.

Animals↗
PubMed1994

Association of chromosomal telomere DNA with nuclear matrix in HeLa cell.

Using Electron Spectroscopic Imaging (ESI), we visualized the in situ binding of nucleic acids to nuclear matrix and 3H-thymidine incorporation which indicates that a small partial DNA bound to nuclear matrix tightly. Furthermore we found that chromosomal telomere DNA could bind to nuclear matrix specifically by the dot and Southern hybridization. The result of the Southwestern blot suggests that telomere DNA has high affinity to lamin B, vimentin and some nuclear matrix proteins. Therefore, the nuclear matrix and lamina of HeLa cell are possibly associated with spatial organization and action of chromosome.

DNA↗
PubMed1993

[The relationship between vaccinia virus DNA replication and intermediate filaments].

Various DNA components which were extracted with gentle cell fractionation from the HeLa cells after 4 h vaccinia virus infection were detected by dot hybridization technique. The virus DNA mainly exist in intermediate filament-lamina-nuclear matrix complex. With DGD embedment free technique and electron microscopic autoradiography, the newly synthesized virus DNA is found to be associated with intermediate filaments. The results of southwestern hybridization demonstrate that vaccinia virus DNA has specific affinity to intermediate filaments and some nuclear matrix proteins.

Blotting, Southern↗
PubMed1993

Surgical correction of hypertelorism. Report of 40 cases.

Forty patients with hypertelorism seen in the past 16 years were reviewed retrospectively. Combined intra- and extracranial surgical approach was used for 37 severe and moderate cases and subcranial approach (U-osteotomy) for 3 moderate cases. Gratifying results were obtained in patients with different types of hypertelorism by a multidisciplinary team. Complications were also reviewed. Of the 37 cases of intra- and extracranial corrections, 1 died, 4 had cerebrospinal fluid leakage and 4 had keratitis. No seizure, cerebral edema, meningitis, blindness, and ptosis occurred in this series. The average age was 13 years and two months. Operating time averaged 6 hours and 50 minutes. Hypertelorism was mostly attributable to craniofacial cleft, craniosynostosis, frontoethmoidal meningoencephalocele, frontonasal fibrous dysplasia, and trauma. Satisfactory esthetic appearance was achieved in most of the cases.

Adolescent↗
PubMed1990

Site-directed mutations in the Sindbis virus 6K protein reveal sites for fatty acylation and the underacylated protein affects virus release and virion structure.

A small hydrophobic polypeptide of 55 amino acids, noted as the 6K protein, is formed during processing of the polyprotein translated from the Sindbis virus subgenomic 26 S mRNA. In the accompanying paper we show that this 6K protein can be found in purified preparations of virions and that it is palmitoylated via thioester bonds with about four covalently bound fatty acids per molecule. To determine acylation sites on 6K and define a role for these fatty acids, we used site-directed mutagenesis to alter cysteine codons in the 6K gene of Sindbis virus cDNA. One of these mutants had a single cysteine replaced with a serine and the second had two adjacent cysteines replaced with an alanine-serine sequence. Transfection of the transcribed RNA from these two cDNAs produced infectious virus which contained 6K proteins that had decreased amounts of fatty acids. Intracellular formation and maturation of virus glycoproteins appeared to be unaffected by the mutations but the release of virus particles from mutant-infected cells was decreased about 70 to 90% from that observed with wild-type virus. Electron microscopy of virus-infected cells and of isolated virions showed that the 6K mutations led to large numbers of aberrant enveloped particles containing multiple nucleocapsids. These results indicate that the 6K protein and its state of acylation are important factors in Sindbis virus assembly and budding. Additional phenotypic changes are reported for virions released from cells infected with the mutationally altered viruses.

Acylation↗
PubMed1990

[The anchoring of newly synthesized adenovirus DNA to the nuclear matrix].

After adenovirus infected HeLa cells were pulse labeled and pulse-chase labeled with 3H-thymidine, the nuclear matrix and DNA remaining tightly bound to the matrix were obtained by sequential cell fractionation. Measuring the radioactivity of labeled DNA indicated that newly synthesized viral DNA specifically attach to the nuclear matrix and the amount of binding DNA is in direct proportion to the viral DNA replication activity: then the DNA gradually detach from the matrix and are involved in viral assembly. Electron microscopic autoradiography of the extracted cells showed the virion and viral DNA associated with the nuclear matrix, and thus further confirmed the anchoring of newly synthesized viral DNA to the nuclear matrix.

Adenoviruses, Human↗
PubMed1989

Evidence that Sindbis virus NSP2 is an autoprotease which processes the virus nonstructural polyprotein.

The four nonstructural proteins (nsP1-4) of Sindbis virus, a member of the Togaviridae family, are initially expressed from the 5' segment of the single-stranded genomic (+)RNA as a polyprotein which is subsequently proteolytically processed. In attempts to identify the protease acting on this nonstructural polyprotein, we established a coupled in polyprotein, we established a coupled in vitro transcription-translation system which was able to faithfully process the major polyprotein when an mRNA encoding all four nonstructural proteins was used. A cDNA plasmid containing the entire Sindbis virus genome positioned immediately downstream of the phage SP6 polymerase promoter was cut with restriction endonucleases at sites located within the genes for the nonstructural proteins and mRNAs transcribed from these DNA fragments. The nsP1-2 and nsP2-3 cleavage sites are alanyl-alanine and both were susceptible to proteolysis in vitro only after all of nsp1 and nsP2 and 157 amino acids of nsP3 were translated. The nsP1-2 site was cleaved from a polyprotein that contained nsP1 and nsP2 and 59 amino acids of nsP3 but not from six polyproteins whose sequences terminated in the nsP2 gene. These data support our hypothesis that the nonstructural polyprotein is processed by a virus autoprotease and we propose that its active site is encoded within the nsP2 sequences.

Capsid↗
PubMed1989

[Effect of nisoldipine on cultured myocardial cells of neonatal rats].

Nisoldipine 1.5 nmol/L, 0.75, and 1.5 mumol/L depressed the beat rates of myocardial cells. The effects were negatively correlated with dosages. Nisoldipine depressed the beat rates increased by calcium chloride 0.15 mmol/L or isoprenaline 1.5 mumol/L and atropine 20 nmol/L. Conversely, the above drugs reversed the beat rates depressed by nisoldipine. Therefore, the acting nisoldipine may be antagonistic to calcium chloride, isoprenaline and atropine. In addition, nisoldipine 10 nmol/L may significantly aggravated the damage to myocardial cells induced by mitomycin C 5 micrograms/ml in which elevated lactate dehydrogenase appeared.

Animals↗
PubMed1987

Expression and glycosylation of the respiratory syncytial virus G protein in Saccharomyces cerevisiae.

A cDNA encoding the entire amino acid sequence of the G glycoprotein of respiratory syncytial virus (RSV) was inserted into a yeast-Escherichia coli shuttle vector such that expression of the virus gene was regulated by the yeast GAL1 promoter. Transformation of Saccharomyces cerevisiae with the vector led to the formation of the G protein when cells were grown in the presence of galactose. Under these conditions the RSV G appeared as a 60- to 65-kDa glycosylated protein. Expression of the G cDNA in secretory mutants of S. cerevisiae yielded a protein of 35 kDa in a mutant unable to glycosylate secreted proteins and a 65-kDa polypeptide in a mutant unable to transport proteins beyond the endoplasmic reticulum. The RSV protein formed in the latter mutant was converted to a 60-kDa protein by endoglycosidase H. Our results show that yeast can recognize the internal signal sequence of RSV G protein and add glycosyl groups to the polypeptide in the endoplasmic reticulum. Evidence is presented for both N- and O-linked glycosylation of the virus glycoprotein.

Acetylglucosaminidase↗
PubMed1986

Expression of genes encoding vesicular stomatitis and Sindbis virus glycoproteins in yeast leads to formation of disulfide-linked oligomers.

Saccharomyces cerevisiae strains transformed with plasmids containing cDNAs coding for the glycoproteins of vesicular stomatitis or Sindbis viruses can be induced to produce large amounts of glycosylated virus glycoproteins. Studies reported here show that these proteins from high molecular weight disulfide-linked oligomers in the yeast endoplasmic reticulum. Oligomers were also found for two genetically altered forms of VSV G; one of these was lacking the membrane anchor domain and the other had the cysteine in the cytoplasmic tail replaced with serine. These oligomers can be separated from the bulk of yeast proteins by brief high-speed centrifugation of yeast extracts prepared by boiling cells with 1% sodium dodecyl sulfate. Treatment with thiol-reducing agents converts the oligomers to soluble monomeric forms, and this procedure leads to a substantial purification of glycoproteins from bulk yeast protein.

Disulfides↗