PubMed Health⌕ Search

Biomedical subjects

M Mao

Publications and source records attributed to M Mao.

33 records · Page 2Linked to original sources
PubMed1999

Overexpression of edg-2/vzg-1 induces apoptosis and anoikis in ovarian cancer cells in a lysophosphatidic acid-independent manner.

Lysophosphatidic acid (LPA) is one of the major growth factors in ascites from ovarian cancer patients and appears to play an important role in proliferation, survival, and invasion of ovarian cancer cells. Recently, several groups have shown that Edg-2, which belongs to the G-protein coupled receptor family, is a functional LPA receptor. Northern blot analysis showed that most ovarian cancer cell lines express Edg-2. Edg-2 expression was especially high in the cisplatin-resistant and slowly proliferating 2780cp cell line and was almost absent from the cisplatin-sensitive and rapidly proliferating A2780 cell line. We thus assessed whether Edg-2 could contribute to changes in cell viability, cell proliferation, or cisplatin resistance. Stable overexpression of Edg-2 in A2780 cells induced an exogenous LPA-independent decrease in proliferation but did not alter cisplatin sensitivity. The LPA-independent decrease in growth rate induced by overexpression of Edg-2 could be explained, at least in part, by Edg-2-induced apoptosis rather than by effects on cell cycle progression. In agreement with the results in stably transfected A2780 cells, transient expression of Edg-2 in Jurkat T cells also induced apoptosis. When cells were separated from the extracellular matrix, they underwent a specialized form of apoptosis called anoikis, which is particularly important in survival of cells in the circulation during metastasis. A2780 cells engineered to overexpress Edg-2 were particularly sensitive to anoikis. These observations suggest that Edg-2 may be a negative regulator for ovarian epithelial cell growth and metastasis.

Animals↗
PubMed1998

Identification of genes expressed in human CD34(+) hematopoietic stem/progenitor cells by expressed sequence tags and efficient full-length cDNA cloning.

Hematopoietic stem/progenitor cells (HSPCs) possess the potentials of self-renewal, proliferation, and differentiation toward different lineages of blood cells. These cells not only play a primordial role in hematopoietic development but also have important clinical application. Characterization of the gene expression profile in CD34(+) HSPCs may lead to a better understanding of the regulation of normal and pathological hematopoiesis. In the present work, genes expressed in human umbilical cord blood CD34(+) cells were catalogued by partially sequencing a large amount of cDNA clones [or expressed sequence tags (ESTs)] and analyzing these sequences with the tools of bioinformatics. Among 9,866 ESTs thus obtained, 4,697 (47.6%) showed identity to known genes in the GenBank database, 2, 603 (26.4%) matched to the ESTs previously deposited in a public domain database, 1,415 (14.3%) were previously undescribed ESTs, and the remaining 1,151 (11.7%) were mitochondrial DNA, ribosomal RNA, or repetitive (Alu or L1) sequences. Integration of ESTs of known genes generated a profile including 855 genes that could be divided into different categories according to their functions. Some (8.2%) of the genes in this profile were considered related to early hematopoiesis. The possible function of ESTs corresponding to so far unknown genes were approached by means of homology and functional motif searches. Moreover, attempts were made to generate libraries enriched for full-length cDNAs, to better explore the genes in HSPCs. Nearly 60% of the cDNA clones of mRNA under 2 kb in our libraries had 5' ends upstream of the first ATG codon of the ORF. With this satisfactory result, we have developed an efficient working system that allowed fast sequencing of 32 full-length cDNAs, 16 of them being mapped to the chromosomes with radiation hybrid panels. This work may lay a basis for the further research on the molecular network of hematopoietic regulation.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1998

[Effects of plasma endothelin-1 and aldosterone on sodium retention in children with nephrotic syndrome].

The effects of plasma endothelin-1 (ET-1) and aldosterone (Ald) on sodium retention in children with nephrotic syndrome were investigated. 14 cases were divided into the edematous stage and non-edematous stage. Plasma ET-1, Ald, and serum osmolarity, albumin (Alb), and Na+ were measured in each stage. The results showed that the plasma ET-1 in edemaous stage increased significantly, compared with that in no-edematous stage (P < 0.01). There was no significant difference in plasma Ald between the edematous stage and the non-edematous stage. Plasma ET-1 was positively correlated with the serum sodium ionic concentration and negatively correlated with the serum Alb(r = 0.486, P < 0.01; r = 0.490, P < 0.01, respectively). In conclusion, the sodium retention with nephrotic syndrome might be correlated with reduction of secreted sodium in the kidney, suggesting that ET-1 plays an important role in pathogenesis.

Aldosterone↗
PubMed1998

[Manifestation and diagnostic value of MR imaging in meningeal carcinomatosis].

OBJECTIVE: To analyze the patterns of MRI manifestation, and to investigate the value of MRI in diagnosis of meningeal carcinomatosis. METHODS: Twenty three cases with meningeal carcinomtosis were analyzed. All cases had pre- and post- contrast MR imagings, typical clinical symptoms and/or positive CSF examination. RESULTS: Of the 23 cases, 22 had abnormal post-contrast meningeal enhancement. The remaining case had hydrocephalus without any enhancement. There were four abnormal MRI patterns: (1)total meningeal enhancement, (2) smooth or nodular enhancement of parts of the meninge, (3)subependymal enhancement, (4)hydrocephalus only. CONCLUSION: MRI is an important assistant method in diagnosis of meningeal carcinomatosis. Post-contrast MRI is mandatory.

Adolescent↗
PubMed1998

[Synthesis and antitumor activity of new heterocyclic 5-fluorouracil derivatives].

Two new compounds I and II of 5-FU derivatives have been synthesized. The structures of the new compounds were confirmed by 1HNMR, MS, IR, UV and elemental analysis. The antitumor activities of compound I was tested against KB, HCT-8 and A2780. The preliminary results showed that the activity of compound I was stronger than that of HCFU and 5-FU.

Antimetabolites, Antineoplastic↗
PubMed1997

Cloning of a gene (RIG-G) associated with retinoic acid-induced differentiation of acute promyelocytic leukemia cells and representing a new member of a family of interferon-stimulated genes.

In a cell line (NB4) derived from a patient with acute promyelocytic leukemia, all-trans-retinoic acid (ATRA) and interferon (IFN) induce the expression of a novel gene we call RIG-G (for retinoic acid-induced gene G). This gene codes for a 58-kDa protein containing 490 amino acids with several potential sites for post-translational modification. In untreated NB4 cells, the expression of RIG-G is undetectable. ATRA treatment induces the transcriptional expression of RIG-G relatively late (12-24 hr) in a protein synthesis-dependent manner, whereas IFN-alpha induces its expression early (30 min to 3 hr). Database search has revealed a high-level homology between RIG-G and several IFN-stimulated genes in human (ISG54K, ISG56K, and IFN-inducible and retinoic acid-inducible 58K gene) and some other species, defining a well conserved gene family. The gene is composed of two exons and has been mapped by fluorescence in situ hybridization to chromosome 10q24, where two other human IFN-stimulated gene members are localized. A synergistic induction of RIG-G expression in NB4 cells by combined treatment with ATRA and IFNs suggests that a collaboration exists between their respective signaling pathways.

Amino Acid Sequence↗
PubMed1997

[Kidney lesions complicated by hypoxic ischemic encephalopathy of neonatal pig].

To study the kidney lesions complicated by hypoxic ischemic encephalopathy (HIE) in newborn, we successfully established a neonatal pig model of HIE. Changes in brain tissue similar to those of newborn in HIE were detected after 2 hours of hypoxia and ischemia. Meanwhile, swelling of kidneys, hemorrhage below encapsules, swellin of tubular epithelial cells, necrosing and falling of a few tubular epithelial cells, and narrowing of tubular lumens were observed. The basement membranes of renal tubules remained normal serum BUN and creatinine increased significantly after experiment compared with before (P < 0.025 and P < 0.05 respectively). The results showed that the kidney of neonatal pig was damaged in HIE. But the injury was not severe. After 72 hours free from hypoxia, the structure and function recovered approximately from the injury.

Animals↗
PubMed1996

RIG-E, a human homolog of the murine Ly-6 family, is induced by retinoic acid during the differentiation of acute promyelocytic leukemia cell.

In vivo all-trans-retinoic acid (ATRA), a differentiation inducer, is capable of causing clinical remission in about 90% of patients with acute promyelocytic leukemia (APL). The molecular basis for the differentiation of APL cells after treatment with ATRA remains obscure and may involve genes other than the known retinoid nuclear transcription factors. We report here the ATRA-induced gene expression in a cell line (NB4) derived from a patient with APL. By differential display-PCR, we isolated and characterized a novel gene (RIG-E) whose expression is up-regulated by ATRA. The gene is 4.0 kb long, consisting of four exons and three introns, and is localized on human chromosome region 8q24. The deduced amino acid sequence predicts a cell surface protein containing 20 amino acids at the N-terminal end corresponding to a signal peptide and an extracellular sequence containing 111 amino acids. The RIG-E coded protein shares some homology with CD59 and with a number of growth factor receptors. It shares high sequence homology with the murine LY-6 multigene family, whose members are small cysteine-rich proteins differentially expressed in several hematopoietic cell lines and appear to function in signal transduction. It seems that so far RIG-E is the closest human homolog of the LY-6 family. Expression of RIG-E is not restricted to myeloid differentiation, because it is also present in thymocytes and in a number of other tissues at different levels.

Amino Acid Sequence↗
PubMed1996

Complete correction of hyperbilirubinemia in the Gunn rat model of Crigler-Najjar syndrome type I following transient in vivo adenovirus-mediated expression of human bilirubin UDP-glucuronosyltransferase.

Recombinant adenoviral vectors are useful for the in vivo expression of genes in hepatocytes. Adenoviral vectors deleted in E1a, E1b, and E3b were constructed and used to study in vivo expression of the major human bilirubin UDP-glucuronosyltransferase isoform (HUG Br1) under the transcriptional control of the cytomegalovirus (CMV) immediate-early promoter-enhancer (H5.010CMV hugBr1). As a control, a recombinant adenoviral vector containing the beta-galactosidase reporter gene driven by the CMV promoter-enhancer was employed (H5. 010CMVlacZ). Recombinant virus was expanded following exposure to E1 transcomplementing (293) cells and concentrated to t titer of approximately 10(13) particles per milliliter. A rat model for Crigler-Najjar syndrome type I deficient in HUG Br1 (ie the Gunn rat) was injected with 5 X 10(9) plaque-forming units (p.f.u.) via the portal vein of either H5.010CMVhugBr1 or H5. 010CMVlacZ. Rats from each set were killed at 3 days, 11 days and 22 days after infusion. Liver total cellular DNA, RNA and protein were analyzed for the transgene and the transgene product at the specified times. Analysis of livers by Southern blot hybridization demonstrates sequence-specific hybridization to adenoviral vector DNA, and Northern blot hybridization demonstrates sequence-specific hybridization to transgene-derived RNA. DNA levels peak at approximately one copy number at 3 days and decline over 22 days. RNA and Western blot analyses demonstrate overexpression of message and protein at 3 days, declining over 22 days. In virto functional assay for bilirubin glucuronosyl-transferase activity demonstrates overexpression of bilirubin UDP-glucurosyltransferase function. In situ hybridization of frozen sections to detect expressed mRNA using beta-galactosidasederived 35S-labeled riboprobes demonstrates adenovirus-derived transgene expression in hepatocytes. Significant drops in serum bilirubin levels were noted following expression of HUG Br1 but not beta-galactosidase. The drop in serum bilirubin correlates with the appearance of bilirubin glucuronides in bile. In summary, recombinant adenoviral vectors were used to demonstrate in vivo complementation of the genetic defect in Gunn rat livers with the HUG Br1 cDNA leading to a resolution of hyperbilirubinemia lasting approximately 7 weeks. These studies suggest that delivery of the HUG Br1 cDNA might provide a reasonable therapeutic benefit for Crigler-Najjar syndrome type I patients, as safe and efficacious gene delivery systems are developed.

Adenoviridae↗
PubMed1992

[Biochemical and immunological characterization of desmosomal proteins].

Desmosmoes were dissolved by incubation at 100 degrees C for 30 minutes in lysis buffer containing 9.5 M urea. SDS-PAGE revealed seven high molecular weight (> 67 kd) bands and some keratins. Seven of these were considered to be major bands. Bands 1 and 2 with M(r) values of 250 kd and 215 kd, called desmoplakins I and II. Polypeptide bands 3, 4a 4b, 5 and 6 had M(r) values of 165kd, 130kd, 115kd, 83kd and 75kd, respectively. 2-2.5mg of Desmoplakin I was obtained by a preparative electrophoresis; the purity reached 93.1%. The isoelectric pH range was between 6.8 and 7.2, and the amino acid compositions displayed a relatively high content of glycine. It was found that McAb Desmoplakin I recognized specifically the 250kd antigenic band by immunoblotting.

Amino Acids↗
PubMed1991

[Isolation of desmosomes: a marker for epithelial tumors].

A simple method is reported for the isolation of desmosomes. The fresh noncornified layers of cow nose epidermis were immersed in 0.1 mol/L citric acid-sodium citrate buffer (pH 2.3, containing 0.5 mmol/L PMSF), and then treated with homogenization and discontinuous sucrose density gradient centrifugation. Desmosomes were located at the 50-56% sucrose interface. Electron microscopy revealed that the characteristic desmosome structure was well preserved, and that a few intermediate filament bundles attached to desmosome plaque were removed by the solubilizing action of the buffer. Approximate 100 mg desmosomes (dry weight) were got from 20g wet noncornified layers of epidermic tissue.

Biomarkers, Tumor↗