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Biomedical subjects

X M Cao

Publications and source records attributed to X M Cao.

At least 19 recordsLinked to original sources
PubMed2005

Serological identification and bioinformatics analysis of immunogenic antigens in multiple myeloma.

Identifying appropriate tumor antigens is critical to the development of successful specific cancer immunotherapy. Serological analysis of tumor antigens by a recombinant cDNA expression library (SEREX) allows the systematic cloning of tumor antigens recognized by the spontaneous autoantibody repertoire of cancer patients. We applied SEREX to the cDNA expression library of cell line HMy2, which led to the isolation of six known characterized genes and 12 novel genes. Known genes, including ring finger protein 167, KLF10, TPT1, p02 protein, cDNA FLJ46859 fis, and DNMT1, were related to the development of different tumors. Bioinformatics was performed to predict 12 novel MMSA (multiple myeloma special antigen) genes. The prediction of tumor antigens provides potential targets for the immunotherapy of patients with multiple myeloma (MM) and help in the understanding of carcinogenesis. Crude lysate ELISA methodology indicated that the optical density value of MMSA-3 and MMSA-7 were significantly higher in MM patients than in healthy donors. Furthermore, SYBR Green real-time PCR showed that MMSA-1 presented with a high number of copy messages in MM. In summary, the antigens identified in this study may be potential candidates for diagnosis and targets for immunotherapy in MM.

Antigens, Neoplasm↗
PubMed1998

Genetic analysis of N-acetyltransferase polymorphism in a Chinese population.

AIM: To study the genetic basis of N-acetylatransferase polymorphism in Chinese. METHODS: Genotypes in 120 healthy Han volunteers from 19 provinces of China were assayed. The 3 common mutant alleles (M1, M2, M3) and one normal wild-type (WT) allele of the N-acetyltransferase (NAT2) gene were detected by allele-specific polymerase chain reaction technique. RESULTS: The NAT2 allele frequencies in 120 Chinese (WT = 0.625, M1 = 0.0458, M2 = 0.188, M3 = 0.142) were different (P < 0.01). The NAT2 genotype distribution for all detected combinations of NAT2 alleles in 120 Chinese subjects was consisitent with Hardy-Weinberg equilibrium (chi 2 = 7.27, nu = 8, 0.7 > P > 0.5). Fifty subjects (41.7%) were homozygous wildtypes, 50 subjects (41.7%) were heterozygous mutants, and 20 subjects (16.7%) were homozygous mutants. CONCLUSION: The lower frequency of mutant M1 allele compared with that of Caucasians explains the low frequency of slow acylators in Chinese.

Acetyltransferases↗
PubMed1997

[Determination of caffeine metabolite for the evaluation of N-acetyltransferase, CYP1A2 and xanthine oxidase activities].

Caffeine was used as a metabolic probe to measure, in 120 healthy volunteers, the activities of three enzymes, deduced to be N-acetyltransferase(NAT2), CYP1A2 and xanthine oxidase (XO). The caffeine metabolites of 5-acetylamino-6-formylamino-3-methyluracil (AFMU), 1-methylxanthine(1X), 1-methyluric acid(1U), 1, 7-dimethylxanthine(17X), and 1, 7-dimethyluric acid(17U) in urine were determined with HPLC after 4-5 hours of caffeine drink. The ratios of AFMU/1X or AFMU/(AFMU + 1X + 1U), (AFMU + 1X + 1U)/17X or (AFMU + 1X + 1U)/17U, and 1U/1X or 1U/(1X + 1U) were used as the index of NAT2, CYP1A2, and XO activities respectively. Frequency distribution analysis of the metabolic ratios of NAT2 indicated two distinct group with 20 slow acetylators and 100 rapid acetylators. Similar CYP1A2 activity was found in Chinese compared with European volunteers. Frequency analysis of CYP1A2 indicated the log normal distribution in 120 Chinese. The CYP1A2 index was much higher in smokers than that in nonsmokers. But no obvious difference was observed between young and old volunteers. The XO index also showed log normal distribution and has the similar value compared with European volunteers. The concentration variations of 1X and 1U in young volunteers were much lower than that in old volunteers.

Adolescent↗
PubMed1997

[HPLC determination of five caffeine metabolites].

An HPLC method for the determination of caffeine metabolites in urine was established. Shim Pack CLC-ODS column (5 microns) was eluted with the mobile phase of methanol--acetonitrile--0.05% acetic acid = 12:1:87 (v/v) at a flow rate of 1.2 ml.min-1, and the ultraviolet absorbance was monitored at 280 nm. The 13 caffeine metabolites and caffeine were well separated and the concentrations of the five metabolites, AFMU, 1U, 1X, 17U, and 17X, were determined. The recoveries of the five metabolites were above 87%, the inter- and intra-day variations were less than 3%. The concentrations of the five metabolites in 120 volunteers were determined. The ratios of the metabolites were employed for the assessment of CYP1A2, NAT, and XO enzymes successfully.

Caffeine↗
PubMed1996

[The terminal monosaccharide of antigenic determinant is involved in the binding of human sperm to specific monoclonal IgA antibody].

In order to know whether terminal monosaccharide of human sperm antigen is involved in stimulating antisperm immune response (especialy IgA production) in mucosal immune system, 33 IgA, 12 IgG and 35 IgM monoclonal antibodies (MAbs) all obtained by intragastrointestinal immunization were used in the present study. The molecular weight (MW) of sperm antigens reactive with MAbs were dectected by Western blotting. The MW range of sperm antigens to the above monclonal IgA, IgM and IgG class, except 12 MAbs not reactive with blotted sperm antigen on nitrocellulose strip, is 10-89 KDa, 11-75 KDa and 12-94 KDa respectively. The sperm antigens were separately blocked and digested with 5 lectins and 4 glycosidases. After that, the capacity of human sperm antigens bind with the above antibodies were determined by ELISA. One or more terminal monosaccharides of sperm antigens are involved with the reaction of most MAbs tested. The loss of terminal alpha-fucose, alpha-N-acetylgalactosamine, alpha-N-acetylglucosamine, mannose and beta-galactose but neuraminic acid in the antigenic determinant of human sperm were found to seriously affect the IgA binding with the corresponding sperm antigen. The binding of IgG with sperm antigen was obviously damaged by the removing of terminal alpha-fucose, alpha-N-acetylgalactosamine and alpha-mannose. The results suggest that the terminal monosaccharides of the sperm antigens play an important role in stimulation of antisperm IgA and other antibodies produced by using intragastrointestinal immunization.

Antibodies, Monoclonal↗
PubMed1993

[The characteristics of monoclonal antibodies and their antigens associated with human sperm acrosome reaction. I. The induction of acrosome reaction and monoclonal antibody production].

Sperm released from the male genital tract must undergo capacitation and acrosome reaction (AR) before binding to oocyte membrane. Changes of sperm components have been found after the capacitation and AR. Based on these changes, the new contraceptive methods and the treatment of the male infertility might be approached. In the present study, in vitro capacitated human sperm were induced to undergo AR in BWW-BSA medium with calcium ionophore A 23187. The fresh human AR sperm in about 50% of sperm population assayed by triple stain technique and/or chlortetracycline fluorescence staining were used for immunization. Twenty three murine hybridomas secreting monoclonal antibodies (McAbs) to non-treated (NT) and/or AR human sperm have been obtained. Of them, 21 McAbs were classified as IgM, others as IgG1 and IgG2a. Based on the immunoreactions of 23 McAbs with NT and AR sperm, they were divided into three groups: group A reacted mainly with the AR sperm, group B with NT sperm, and group C with both AR and NT sperm. The cross reaction of these McAbs with human leukemia cell lines was detected by ELISA and the discrepant reactions were observed.

Acrosome↗
PubMed1993

[The characteristics of monoclonal antibodies and their antigens associated with human sperm acrosome reaction. II. Effects of the monoclonal antibodies on sperm function, sperm antigen localization and immunoblotting].

By using microassay, the strong human sperm agglutination were caused by 9 of 23 monoclonal antibodies (McAbs) obtained by immunization with fresh human acrosome-reacted (AR) sperm, which was induced by ionophore A 23187, but no one of them demonstrated the ability to immobilize human sperm. In contrast to most studies reported by other laboratories, the antigens recognized by most of McAbs in the present study were located in equatorial segment and midpiece of human sperm, and no one in acrosome region of human sperm. The binding pattern of some McAbs on non-treated and AR sperm was found to be different. The human sperm proteins ranged in the size of 16-146 kDa were demonstrated to be reacted with 9 of 23 McAbs by immunoblotting. Moreover, the cross reaction of 23 McAbs with mouse and tree shrew sperm was detected by indirect immunofluorescent assay. These results suggest that AR sperm possesses peculiar immunogenic properties.

Acrosome↗
PubMed1992

Regulation of the Egr-1 gene by tumor necrosis factor and interferons in primary human fibroblasts.

Treatment of quiescent primary human fibroblasts with tumor necrosis factor (TNF) alpha, TNF-beta, interleukin-1, interferon (IFN) alpha, IFN beta, or IFN gamma induced Egr-1 mRNA. In primary human fibroblasts TNF-alpha and TNF-beta were mildly mitogenic and IFN alpha and IFN gamma were growth inhibitory. However, in HeLa cells TNF but not IFN induced the expression of Egr-1 mRNA, while both cytokines inhibited HeLa cell division. Kinetic measurements of Egr-1 gene expression showed that TNF-alpha, TNF-beta, and IFN gamma increased the cellular concentration of Egr-1 mRNA within 30 min. A maximum induction of Egr-1 mRNA was detected at approximately 60 min which dropped to basal level by 180 min. Induction was inhibited by H7 and staurosporine but not by HA1004, indicating the involvement of a functional protein kinase C. The Egr-1 message was translated and the cellular Egr-1 protein detected within 60 min of cytokine treatment. Despite similar Egr-1 mRNA induction, the amount of Egr-1 protein translated in IFN alpha- and IFN gamma-treated cells was lower than in those treated with TNF-alpha and TNF-beta, and highest in the EGF-treated primary human fibroblasts. Indeed, the level of Egr-1 protein translated in these cells correlated proportionally with both the phosphorylation of cap-binding protein (eukaryotic initiation factor) and the amount of cellular DNA synthesis in the variously treated fibroblasts. These results suggest that both growth stimulatory and inhibitory cytokines can regulate Egr-1 gene expression at the transcriptional and translational level. However, the combination of these regulatory controls may determine the cellular concentration of the Egr-1 gene product and hence, its effect on cell proliferation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1991

v-Src activates mitogen-responsive transcription factor Egr-1 via serum response elements.

Activating the protein-tyrosine kinase activity of v-Src in murine fibroblasts leads to increased expression of Egr-1, a mitogen-responsive transcription factor. v-Src-induced expression of Egr-1 is independent of protein synthesis and is controlled at the level of transcription. Target sequences responsive to v-Src-induced signals were investigated using deletion mutant and analysis of the Egr-1 promoter. Upstream Egr-1 promoter sequences linked to a reporter gene were cotransfected with a v-Src expression vector into NIH 3T3 cells. v-Src-enhanced gene expression from the Egr-1 promoter was dependent upon the presence of CC(A/T)6GG elements. The CC(A/T)6GG motif forms the core element of serum response elements (SREs) and is the binding site for serum response factor. The Egr-1 promoter sequences responsive to v-Src contained four SREs. Sequential deletion of these SREs reduced v-Src responsiveness to basal transcription levels. A single SRE from this region was able to confer v-Src responsiveness to a heterologous promoter, and a mutation to the CC(A/T)6GG box of this SRE abolished v-Src-enhanced gene expression. Thus, an early response of v-Src-induced intracellular signaling is the transcriptional activation of a growth factor-responsive transcription factor via an SRE.

Animals↗
PubMed1991

Signaling through surface IgM in tolerance-susceptible immature murine B lymphocytes. Developmentally regulated differences in transmembrane signaling in splenic B cells from adult and neonatal mice.

During the course of B lymphocyte development, newly emerging surface Ig+ B cells pass through a stage when Ag-Ag receptor interactions lead not to immune responsiveness but to a state of functional tolerance. We have explored the molecular basis of antigenic nonresponsiveness and tolerance susceptibility using tolerance-susceptible surface Ig+ splenic B lymphocytes from neonatal mice and anti-mu chain antibodies as a polyclonal ligand. In this population of cells, surface IgM is uncoupled from the inositol phospholipid (PI)-hydrolysis pathway at a point proximal to the receptor; anti-mu antibodies did not stimulate inositol phosphate generation despite the fact that PI-hydrolysis was observed after treatment with A1F4, implicating the existence of a functional G protein and phospholipase C. Further evidence for a difference early in the signal transduction pathway stems from the finding that anti-mu stimulation does not induce the expression of two immediate/early PKC-linked genes egr-1 and c-fos. This appears to be the primary signaling difference between the mature and immature B cells from the neonatal mouse splenic population, as these cells undergo a G0-G1 cell cycle phase transition when surface IgM is bypassed using phorbol diester and calcium ionophore. Interestingly, despite undetectable levels of PI-hydrolysis, we observed equivalent receptor-mediated changes in intracellular calcium when comparing the immature and mature populations. These results indicate incomplete coupling of surface IgM to the signal transduction machinery operative in mature, immunocompetent B cells and suggests a molecular mechanism accounting for the differential processing of surface IgM signals into activation vs tolerogenic responses observed in these two stages of B cell development.

Aging↗
PubMed1991

Comparison of the 5' and 3' untranslated genomic regions of virulent and attenuated foot-and-mouth disease viruses (strains O1 Campos and C3 Resende).

The complete 5' and 3' non-coding regions of two attenuated South American foot-and-mouth disease virus (FMDV) vaccine strains, O1C-O/E and C3R-O/E, and their corresponding virulent parental strains, O1 Campos and C3 Resende, have been cloned from polymerase chain reaction-amplified primary cDNA. Differences observed in the derived nucleotide sequences between attenuated and virulent viruses seem not to affect regulatory signal structures, supporting the theory that genetic variations, primarily in the 3' halves of the viral genomes, contribute to the attenuation phenotype of the vaccine strains. In addition, this is the first report on the complete sequence of the 5' untranslated region of a C-type aphthovirus. Approximately 10% of the nucleotides differ from the corresponding known sequences of serotypes A or O.

Aphthovirus↗
PubMed1991

[Effect of angiotensin converting enzyme inhibitor on arterial wall thickening in coarctation hypertension].

In order to clarify the role of renin-angiotensin systems on arterial wall thickening in hypertension, the effect of angiotensin converting enzyme inhibitor, captopril, in rats with aortic coarctation was studied. Captopril was given by intragastric instillation, 3 mg/kg B, W. twice a day, since the 2nd day after the operation, and the animals were examined 4 to 6 weeks later. Blood pressures from carotid and femoral arteries were recorded directly; the heart and standardized segments of the aorta were weighted; aorta, coronary and renal arterioles were studied morphometrically; renin activity, angiotensin II and aldosterone concentrations were assayed. The results showed that captopril reduced significantly thickening of the aortic and arteriolar wall in both the hypertensive forequarters and the normotensive hindquarters. This suggests that renin-angiotensin system plays a role in the development of arterial wall thickening in hypertension.

Animals↗
PubMed1990

Egr-1 expression in surface Ig-mediated B cell activation. Kinetics and association with protein kinase C activation.

We have studied the expression of an immediate/early type gene, Egr-1, in murine B lymphocyte responses to Ag receptor-generated signals. The Egr-1 gene encodes a zinc finger protein with sequence-specific DNA binding activity and is believed to act as an intracellular "third messenger," to couple receptor-generated signals to activation-associated changes in gene expression. We show here that Egr-1 mRNA expression is rapidly and transiently (returning to basal levels by 6 h) induced after receptor crosslinking with anti-receptor antibodies. Egr-1 protein expression is more prolonged, maintaining detectable levels through 12 h. The induction of Egr-1 is a primary response to Ag receptor signaling, as it is independent of new protein synthesis and is inhibited by actinomycin D. We have also examined the linkage of Egr-1 to known signaling pathways associated with G0 to G1 transition by these cells in response to signals generated through the B cell Ag receptor. Egr-1 mRNA was not induced after elevation of intracellular free Ca2+. In contrast, the pharmacologic agents PMA and SC-9, which directly activate protein kinase C, both cause marked increases in Egr-1 mRNA levels with the same kinetics as observed after anti-receptor antibody stimulation. Further, the protein kinase C inhibitors H7, sangivamycin, and staurosporin block anti-receptor antibody-induced expression of Egr-1, thus, B cell Ag receptor-linked Egr-1 expression is likely coupled to the protein kinase C component of transmembrane signaling. Preliminary promoter mapping studies are consistent with this conclusion, because both PMA and anti-receptor antibody act through the same or overlapping cis-regulatory elements.

Animals↗
PubMed1990

Methylation of an immediate-early inducible gene as a mechanism for B cell tolerance induction.

Stage-specific gene regulation is important in determining cell function during development. Immature B cells expressing membrane-bound immunoglobulin M (mIgM) are sensitive to antigen-induced tolerance, whereas mature B cells are activated by antigen. Previous studies have established an association between Egr-1 gene induction and antigen receptor (mIgM)-mediated activation of mature B cells. Here it is shown that the immature B cell line WEHI-231 and tolerance-sensitive bone marrow-derived B cells do not express Egr-1. It is further shown that lack of inducible expression in these cells is due to specific methylation of the Egr-1 gene. Thus, covalent inactivation of an activation-associated gene may explain tolerance sensitivity at specific stages of B cell development.

Animals↗
PubMed1990

Identification and characterization of the Egr-1 gene product, a DNA-binding zinc finger protein induced by differentiation and growth signals.

Egr-1 is an immediate-early response gene induced by diverse signals that initiate growth and differentiation. Its cDNA sequence predicts a protein with zinc fingers. We have generated an antiserum to the Egr-1 gene product and identified it as an 80-kilodalton short-lived protein in serum-stimulated mouse fibroblasts. The rat Egr-1 product has also been identified in nerve growth factor-induced PC12 cells. In addition, we show by cell fractionation and immunocytochemistry that the Egr-1 protein is located in the nucleus. We also demonstrate that it is phosphorylated. In vitro-generated Egr-1 protein binds with high affinity to the sequence CGCCCCCGC in a zinc-dependent manner.

Animals↗
PubMed1990

Transcriptional activation and repression by Fos are independent functions: the C terminus represses immediate-early gene expression via CArG elements.

The Fos-Jun complex has been shown to activate transcription through the regulatory element known as the AP-1 binding site. We show that Fos down regulates several immediate-early genes (c-fos, Egr-1, and Egr-2) after mitogenic stimulation. Specifically, we demonstrate that the target for this repression is a sequence of the form CC(A/T)6GG, also known as a CArG box. Whereas Fos bound to the AP-1 site through a domain rich in basic amino acids and associated with Jun via a leucine zipper interaction, mutant Fos proteins lacking these structures were still capable of causing repression. Furthermore, Jun neither enhanced nor inhibited down regulation by Fos. Critical residues required for repression are located within the C-terminal 27 amino acids of c-Fos, since v-Fos and C-terminal truncations of c-Fos did not down regulate. In addition, transfer of 180 c-Fos C-terminal amino acids to Jun conferred upon it the ability to repress. Finally, Fra-1, a Fos-related protein which has striking similarity to Fos in its C-terminal 40 amino acids, also down regulated Egr-1 expression. Thus, Fos is a transcriptional regulator that can activate or repress gene expression by way of two separate functional domains that act on distinct regulatory elements.

Animals↗
PubMed1988

5' flanking sequence and genomic structure of Egr-1, a murine mitogen inducible zinc finger encoding gene.

Egr-1 is a murine zinc finger encoding cDNA whose expression is modulated by a variety of ligand-receptor interactions and is often coregulated with c-fos (1). This study reports the isolation of a mouse Egr-1 genomic clone, its intron-exon structure, and 935 bp of 5' flanking sequence. The gene spans about 3.8 kb and consists of 2 exons and one 700 bp intron. S1 nuclease protection and primer extension analysis were used to define the transcription initiation site. "TATA" and "CCAAT" sequences were located at nucleotides -26 and -337 respectively. In addition, there exist five elements whose sequence is nearly identical to the inner core 10 nucleotide region (CCATATTAGG) of the c-fos serum response element, four Sp1 consensus sequences, two AP1 target sequence analogs, and two potential cAMP response elements. These results will ultimately lead to a detailed definition of the intracellular events regulating Egr-1 expression.

Animals↗