PubMed Health⌕ Search

Biomedical subjects

M Geng

Publications and source records attributed to M Geng.

18 recordsLinked to original sources
PubMed2001

Proteomics of glycoproteins based on affinity selection of glycopeptides from tryptic digests.

Identification of glycoproteins in complex mixtures derived from either human blood serum or a cancer cell line was achieved in a process involving the steps of (1) reduction and alkylation, (2) proteolysis of all proteins in the mixture with trypsin, (3) affinity chromatographic selection of the glycopeptides with an immobilized lectin, (4) direct transfer of the glycopeptide fraction to a reversed-phase liquid chromatography (RPLC) column and further fractionation by gradient elution, (5) matrix-assisted laser desorption ionization mass spectrometry of individual fractions collected from the RPLC column, and (6) peptide identification based on a database search. The types of glycoproteins analyzed were; (1) N-type glycoproteins of known primary structure, (2) N-type glycoproteins of unknown structure, and (3) O-type glycoproteins glycosylated with a single N-acetylglucosamine. Identification of peptides from complex mixtures was greatly facilitated by either C-terminal sequencing with a carboxypeptidase mixture or by comparing chromatographic behavior and mass to standards, as in the case of a known protein. In addition, deglycosylation of peptides with N glycosidase F was necessary to identify N-type glycoproteins of unknown structure. The strength of this approach is that it is fast and targets specific molecular species or classes of glycoproteins for identification. The weakness is that it does not discriminate between glycoforms.

Amino Acid Sequence↗
PubMed2001

[The Immunophenotypical features of t (8; 21) (q22; q22) acute myeloid leukemia].

OBJECTIVE: To study the predictive value of immunophenotypical features in t (8; 21) (q22; q22) acute myeloid leukemia (AML). METHODS: Morphological/cytochemical, flow cytometric immunophenotyping, cytogenetic analyses (MIC) and RT-PCR were performed in 294 previously untreated AML. RESULTS: (1) In 294 AML patients, t (8; 21) AML were 21.8% (64); in AML-M(2), t (8; 21) AML were 54.7%; and in t (8; 21) AML, AML-M(2) were 81.3%. (2) Compared with control group, CD(19) and CD(34) expressions were higher, and CD(33) expression was lower (P < 0.001) in t (8; 21) AML. (3) If the cut-off value of CD(19) positive was >or= 20%, CD(19) positive rate was 13.6% (40/294) in AML, and 50% (32/64) and 3.5% (8/230) (P < 0.001) in t (8; 21) AML and control group. (4) CD(19)(+) and/or CD(34)(+) t (8; 21) AML accounted for 90.6% (58/64) of t (8; 21) AML and CD(19)(-)/CD(34)(-) for 9.6% (6/64). CONCLUSION: In t (8; 21) AML, especially M(2)/t (8; 21), CD(19) and CD(34) expressions were high. CD(19) was one of predictive markers of t (8; 21) AML.

Adolescent↗
PubMed2000

Strategy for qualitative and quantitative analysis in proteomics based on signature peptides.

This paper describes a new analytical strategy for identifying proteins in concentration flux based on isotopic labeling peptides in tryptic digests. Primary amino groups in peptides from control and experimental samples were derivatized with acetate and trideuteroacetate, respectively. After mixing samples thus labeled from these two sources, the relative concentration of peptides was determined by isotope ratio analysis with MALDI and ESI mass spectrometry. More than a 100-fold difference in relative concentration could be detected. Simplification of complex tryptic digests prior to mass spectral analysis was achieved by selection of histidine-containing peptides with immobilized metal affinity sorbents or of glycopeptides by lectin columns. Because most of these peptides have sequences that are unique to a single protein, they are a signature of the protein from which they were derived; providing a facile route to protein analysis.

Chromatography, Affinity↗
PubMed2000

Signature-peptide approach to detecting proteins in complex mixtures.

The objective of the work presented in this paper was to test the concept that tryptic peptides may be used as analytical surrogates of the protein from which they were derived. Proteins in complex mixtures were digested with trypsin and classes of peptide fragments selected by affinity chromatography, lectin columns were used in this case. Affinity selected peptide mixtures were directly transferred to a high-resolution reversed-phase chromatography column and further resolved into fractions that were collected and subjected to matrix-assisted laser desorption ionization (MALDI) mass spectrometry. The presence of specific proteins was determined by identification of signature peptides in the mass spectra. Data are also presented that suggest proteins may be quantified as their signature peptides by using isotopically labeled internal standards. Isotope ratios of peptides were determined by MALDI mass spectrometry and used to determine the concentration of a peptide relative to that of the labeled internal standard. Peptides in tryptic digests were labeled by acetylation with acetyl N-hydroxysuccinimide while internal standard peptides were labeled with the trideuteroacetylated analogue. Advantages of this approach are that (i) it is easier to separate peptides than proteins, (ii) native structure of the protein does not have to be maintained during the analysis, (iii) structural variants do not interfere and (iv) putative proteins suggested from DNA databases can be recognized by using a signature peptide probe.

Amino Acid Sequence↗
PubMed2000

[Cytogenetics and clinical studies of hematologic malignancies with 11q23 abnormalities in China].

OBJECTIVE: To evaluate the association between 11q23 abnormalities and the clinical, hematologic, prognostic aspects of hematologic malignancies. METHODS: A total of 6000 cases of hematologic malignancies from our hospital and near regions in China were investigated between October 1985 and November 1998. Chromosome preparations were made on bone marrow cells by using direct method and/or unstimulated short-term cultures. Karyotypes were analyzed by R-banding technique and expressed according to ISCN(1995). RESULTS: 11q23 abnormalities were found in 28 of 6000 cases with hematologic malignancies(0.47%). It may be separated into seven cytonetic categories: t(4;11)(q21;q23)(ten cases), t(11;19)(q23;p13)(five cases), t(9;11)(p12;q23)(two cases), t(10;11)(p15;q23)(two cases), t(6;11)(q27;q23) (one case), del(11)(q23)(seven cases), and t(11;?)(q23;?)(one case). The diagnoses included acute myeloid leukemia in 14 cases (M(2a), three; M(4), two; M(5a), one; M(5b), eight), acute lymphoblastic leukemia(ALL) in 10 cases, myelodysplastic syndrome in three cases and malignant histiocytosis in one case. All 10 cases with t(4;11) anomaly were ALL. Follow-up data were available for 22 of them. Their median survival was 113 days. The patients may be grouped according to the presence or absence of additional abnormalities and/or normal karyotype. The median survival was 75 days for five patients with 11q23 anomaly only, 18 days for two patients with 11q23 and additional abnormalities, 135 days for 10 patients with 11q23 anomaly, additional abnormalities and normal karyotype, and 150 days for 5 patients with 11q23 anomaly and normal karyotype. CONCLUSION: 11q23 abnormalities were mainly seen in ALL and acute monocytic leukemia. Their prognosis was very poor. Both additional abnormalities and lack of normal karyotype had adverse effects on the survival of patients. Thus, they represent a unique clinical-cytogenetic association. 11q23 abnormality; hematologic malignancy; acute monocytic leukemia; acute lymphoblastic leukemia; prognosis

Adolescent↗
PubMed2000

[A system of microcomputer analysis for biological oxygen consumption and its application].

This paper introduces a microcomputer system of data analysis and methods of measuring oxygen consumption for biological materials. The system overcame some disadvantages of operating inconvenience and difficulties of collective and analytic data by traditional means. The system possesses functions of automatic enactment, collection, save/take and analysis for many experimental data. It can be used to measure oxygen consumption of tissues, cells and mitochondria.

Animals↗
PubMed2000

[Chromosome t (4; 11) acute lymphoblastic leukemia: an analysis of 10 cases].

OBJECTIVE: To characterize morphologically, immunophenotypically, cytogenetically and clinically the acute lymphoblastic leukemia (ALL) with t (4; 11) (q21; q23). METHODS: Ten cases of t (4; 11) ALL were reported. Of them, eight patients were de novo and two relapsed. The patients were treated with combination chemotherapy of DOPL or VP regimen. Immunophenotypic analysis was performed by flow cytometry in seven cases. Cytogenetic analysis was performed using bone marrow cells prepared directly and/or after 24h culture (case 7 using peripheral blood). RHG banding was used for karyotypic analysis. RESULTS: Ten (3.5%) of 285 ALL patients were found to be t (4; 11) ALL. In these 10 patients, increased WBC (> 100 x 10(9)/L) was found in 6 cases. Liver, spleen and/or lymph nodes were involved in all. t (4; 11) was detected as a single abnormality in 5 karyotypes whereas the other 5 showed additional aberration besides t (4; 11). Six patients were CD(19) (+), five were CD(22) (+) and one was HLA-DR (+), CD(5) (+), supporting that most cases of t (4; 11) ALL were B cell origin. Median survival time was 5.5 months in the present series. CONCLUSION: t (4; 11) ALL was a subtype with unique clinical and cytogenetic features, and had a poor prognosis.

Adolescent↗
PubMed1999

Strategies for the detection of disease genes in pancreatic cancer.

The present review summarizes our strategies aimed at identifying and characterizing genetic alterations occurring at the transcriptional and chromosomal level in pancreatic cancer. To study transcriptional alterations we have used a number of techniques including modified versions of differential hybridizations and cDNA RDA (representational difference analysis). These approaches have led to the identification of more than 500 genes with differential expression in pancreatic cancer. To study chromosomal aberrations occurring in pancreatic cancer tissues we used comparative genomic hybridization (CGH). This allowed the identification of a number of chromosomal regions containing putative tumor suppressor genes or oncogenes. Genes isolated in both approaches represent potential new disease genes for pancreatic cancer and are at present being characterized by individual or serial analysis.

Amino Acid Sequence↗
PubMed1999

Novel technology for detection of genomic and transcriptional alterations in pancreatic cancer.

AIM: The present review summarizes our strategies aimed at identifying and characterizing genetic alterations occurring at the transcriptional and chromosomal level in pancreatic cancer. METHODS: To study transcriptional alterations we have used a number of techniques including modified versions of differential hybridizations and cDNA-RDA (representational difference analysis). Comparative genomic hybridization (CGH) was used to study chromosomal aberrations occurring in pancreatic cancer tissues. RESULTS: The study of transcriptional alterations led to the identification of more than 500 genes with differential expression in pancreatic cancer. The sum of these alterations represented the first expression profile characteristic for pancreatic tumors. The CGH analysis allowed the identification of a number of chromosomal regions containing putative tumor suppressor genes or oncogenes. These regions are presently being characterized at the molecular level. In a first approach the myb-oncogene was identified as the relevant oncogene of an amplification on 6q occurring in up to 10% of pancreatic cancer patients. CONCLUSIONS: Genes isolated in both approaches represent potential new disease genes for pancreatic cancer and are at present being characterized by individual or serial analysis.

Chromosome Aberrations↗
PubMed1999

Dose-related effect of irradiation on circadian rhythm of cellular messengers in neural and immune system of mouse.

OBJECTIVE: To explore toxic effect of gamma-irradiation on circadian rhythms of cAMP and cGMP in signal pathway between the central nuclei and peripheral lymphocyte. METHODS: 60Co gamma-ray of 0.5 Gy and 5.0 Gy was applied to groups of mice at each circadian timepoint of a day. 24 hours after the irradiation, the pineal and suprachiasmatic nuclei (SCN) were removed, and the T lymphocytes in blood were separated by a step-centrifugal and nylon-filter treatment, for measurements of cAMP and cGMP by using the RIA procedure. The results were expressed as circadian rhythms of the cAMP/cGMP ratio derived from the Cosinor analysis. RESULTS: The daily average cAMP/cGMP ratio in cells of SCN, pineal, serum and lymphocyte changed according to the dose of irradiation at which the mice were exposed. The high dose of 5 Gy increased the ratio, and the low dose of 0.5 Gy decreased the ratio. There was a significant difference of cAMP/cGMP levels between the irradiated and the control groups, as well as between CT00:00 and CT12:00 of a day. In addition, the peak phases of the cAMP/cGMP ratio at the low-dose groups appeared in advance from about 2 to 8 hours, whereas those at the high-dose groups were delayed from about 3 to 6 hours in comparison to that of the normal mice. CONCLUSION: Toxic effect of gamma-irradiation on the cAMP/cGMP circadian rhythm in the central nuclei and peripheral lymphocyte could be characterized by a low-dose hormesis.

Animals↗
PubMed1999

[Preparation of collagen-based materials for wound dressing].

This article addressed the methods to develop collagen-based materials for wound dressing. Fresh frozen bovine tendon was treated with 0.05 M acetic acid at pH 3.2 for 48-72 h, then it was homogenized, filtered, and after the process of adding chondroitin sulphate(8%), it was dbubblized; thus 1.5%-2.5% collagen solution was finally prepared. The solution was lyophilized in prefrozen or un-prefrozen mold. The collagen sponge was crosslinked with 0.25% glutaraldehyde for 24 h. Three other wound dressings were developed by similar method, namely collagen membrane with polyurethane membrane onlay, polyurethane-coated collagen membrane and collagen membrane on gauze. It was demonstrated that the property of frozen bovine tendon was stable, and the prepared collagen sponge contained pores of 50-400 microns in diameter. Some factors influencing pore structure and size in the collagen sponge were discussed. The results of this preliminary study suggested that the collagen could be used as wound dressing.

Animals↗
PubMed1998

Expression of a fusion protein of scFv-biotin mimetic peptide for immunoassay.

We constructed two fusion proteins of scFv linked to biotin mimetic sequence (BMS) via different linkers, and expressed them in the Pichia pastoris expression/secretion system. We found that both bi-functional scFv proteins exhibited their intrinsic binding activities to antigen CA125 determined in competitive radioimmunoassay experiments, but the fusion protein with a spacer between the scFv and BMS (scFv-spacer-BMS) showed higher binding activity of streptavidin than the one with c-Myc peptide as a linker.

Antibodies, Bispecific↗
PubMed1998

Isolation of differentially expressed genes by combining representational difference analysis (RDA) and cDNA library arrays.

The difference products (DP) of representational difference analyses (RDA) were used as hybridization probes on cDNA arrays. The effectivity of RDA products obtained with increasing driver/tester ratios (DP 1 = 100:1, DP 2 = 800:1 and DP 3 = 400,000:1) to isolate differentially expressed genes was compared with the effectivity of conventional differential hybridizations. Pacreatic cancer and control tissues were used as a test system to isolate differentially expressed genes. The use of RDA products as hybridization probes showed two major advantages: (i) a reliable identification of true differential signals; and (ii) only one autoradiograph had to be analyzed, which eliminated the need for a laborious subtraction of signal intensities obtained with different cDNA probes. Increasing driver/tester ratios in iterative rounds of RDA delivered more specific results, though the total yield of differential clones was gradually reduced. In this situation, the intermediate RDA product DP 2 provided the best compromise.

Blotting, Northern↗
PubMed1997

An engineered bivalent single-chain antibody fragment that increases antigen binding activity.

Bivalent single chain Fv (scFv) was constructed by fusing a polypeptide extension containing one or two cysteines to the COOH-terminus of an scFv antibody fragment. The scFv protein was expressed and secreted in a recombinant Pichia pastoris system as a dimer with a C-terminal disulfide bridge, as determined by Western blot analysis under non-reducing conditions. We found that the scFv construct with one cysteine in the C-extension (scFv-1Cys) exhibited a much higher dimer/monomer ratio than the two cysteine counterpart (scFv-2Cys). Binding activity measurements performed by means of a competitive radioimmunoassay showed that scFv-1Cys exhibited specific antigen binding activity, which was almost the same as that of the parental MAb, and approximately four- and fortyfold higher than those of the control scFv monomer and scFv-2Cys.

Amino Acid Sequence↗
PubMed1997

The influence of transforming growth factor beta 1 on the expression of genes coding for matrix metalloproteinases and tissue inhibitors of metalloproteinases during regeneration from cerulein-induced pancreatitis.

Enhanced synthesis and deposition of extracellular matrix (ECM) components is a characteristic feature during regeneration from acute cerulein-induced pancreatitis in rats. Transforming growth factor beta 1 (TGF beta 1) has been suggested to be an important modulator of the ECM by interfering with a number of essential processes such as the synthesis of ECM components. To study the involvement of the ECM degrading proteases (matrix metalloproteinases; MMPs) and their specific inhibitors in the process of pancreatic regeneration, we examined the expression of these genes on the transcript level and the activation of the corresponding enzymes by use of zymographies. Pancreatic RNA and protein were extracted from rats sacrificed 1, 2, 3, 5, and 7 days after induction of cerulein pancreatitis. To investigate the influence of TGF beta on gene expression of ECM proteases and their specific inhibitors, we blocked the activity of TGF beta 1 during regeneration from acute pancreatitis by use of neutralizing antibodies against TGF beta 1. Steady levels of 72-kD type IV collagenase (MMP-2), stromelysin (MMP-3), and tissue inhibitor of metalloproteinase 2 (TIMP-2) mRNA were significantly increased 2 days after induction of pancreatitis. MMP-9 and MMP-3 enzyme activity was elevated 12 h after induction of pancreatitis, whereas MMP-2 activity increased 12 h later. Inhibition of TGF beta 1 by neutralizing antibodies only reduced the amount of stromelysin transcripts throughout pancreatic regeneration. In summary, ECM degrading proteases, in particular stromelysin, appear to be involved in ECM remodeling during pancreatic regeneration. TGF beta 1 may be responsible for regulation of stromelysin transcription.

Animals↗
PubMed1997

[Water vapor permeability measurement of the materials used as a wound covering].

This paper introduces a new apparatus and method that suits to measuring the water vapor transmission rate (WVTR) of wound covering materials. WVTR of synthetic materials, amniotic membrane, porcine and cadaveric skin was measured under different conditions of four temperatures, three mediums, and "water cup" or "inverted water cup". The temperature was in close relationship with the WVTR except Omiderm, amniotic membrane, and cadaveric skin between 30 degrees C and 37 degrees C groups. The medium did not affect the WVTR (P > 0.05). There was significant difference between the "water cup" and "inverted water cup" groups(P < 0.01). This study suggests that the apparatus is easy-to-operate, reliable and suitable for the measurement of WVTR of burn wound coverings and other membranous materials.

Bandages↗
PubMed1996

A pancreatic cancer-specific expression profile.

We present an approach making use of technology established in the context of the genome project to describe a pancreatic cancer-specific expression profile and to identify new potential disease genes or disease-associated-genes. By use of gridded arrays of pancreatic cancer cDNA libraries and differential hybridizations we show that 4% the gridded cDNA library clones contain sequences preferentially expressed in pancreatic cancer. EST-sequencing of 369 distinct (408 total), differentially expressed sequences identified novel genes (32.5%) or homologs to EST-sequences with unknown function (26.3%). Homologies to known genes allow to determine a pancreatic cancer-specific expression profile, which provides for the first time evidence for complex primary and secondary alterations of gene expression responsible for the development of the phenotype of pancreatic cancer cells. In addition this has led to the identification of novel differentially expressed genes, which represent potential oncogenes or disease-associated markers and may be helpful for the development of therapeutic or diagnostic modalities.

Animals↗