Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Comparing the marker enzymes horseradish peroxidase (HRP), alkaline phosphatase (AP) and beta-galactosidase (beta Gal) in IgG-coupled form with respect to their temperature-dependent kinetics over a period of 22 h the temperature of 37 degrees C warrants highest substrate turnover for all enzymes at all reaction times using fluorogens. Also applying chromogens the optimum temperature for beta Gal is 37 degrees C and depends for HRP and AP on the reaction time. The substrate turnover of HRP using ABTS as chromogen is much higher compared to the other enzymes--both related to mol enzyme (molar activity) and to gram enzyme (specific activity). The turnover decreases for all enzymes in different degrees after coupling to IgG. The turnover of fluorogenic substrates is lower for all enzymes than the turnover of chromogenic substrates but due to the more sensitive detection of fluorogenic products the detection limits for all conjugates were lowered too--especially for beta Gal-IgG by a factor of 333 compared to the colorimetric procedure. In a 2-site binding enzyme immunoassay for alpha-1-fetoprotein (AFP) the detection limit for AFP was reduced by a factor of 2 only by the fluorimetry compared to the colorimetry with all 3 marker enzymes. The HRP-IgG conjugates warranted lowest detection limits for AFP (0.5-1 microgram/1), highest analytical sensitivity (slope of standard curves) at shortest periods of substrate reaction compared to the other enzymes.
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PMID:Which of the commonly used marker enzymes gives the best results in colorimetric and fluorimetric enzyme immunoassays: horseradish peroxidase, alkaline phosphatase or beta-galactosidase? 392 20

To target gene expression to malignant hepatic cells, we have constructed recombinant retroviral vectors containing a reporter gene encoding nuclear beta-galactosidase (nls-LacZ) under transcriptional control of regulatory sequences from the rat alpha-fetoprotein (AFP) or human insulinlike growth factor II (IGFII) genes. The AFP and IGFII P3 promoters activate transcription during fetal development and are often reactivated in hepatocellular carcinoma (HCC). Infection of several cultured cell types with the retroviral vector containing the IGFII P3 sequence resulted in expression of the reporter gene in all cell lines tested, including those that do not produce IGFII. In contrast, selective expression was achieved by vectors containing the AFP transcriptional regulatory sequence. Nuclear beta-galactosidase activity was detectable in cells from lines that produce AFP, and not in cells that do not express the AFP gene. In most infected cell lines, retroviral RNA synthesis from the 5' LTR was inhibited, and deletion of the retroviral LTR enhancer did not change expression from either the IGFII P3-nls-LacZ or the AFP-nls-LacZ cassettes. After treatment of cells with 12-O-tetradecanoylphorbol-13-acetate and epidermal growth factor (EGF), the decrease in concentrations of endogenous AFP messenger RNA (mRNA) and nls-LacZ mRNA transcribed from the transferred AFP regulatory sequence were similar. In the context of an integrated provirus, the AFP transcriptional regulatory sequence is therefore subject to similar regulatory control as that of the endogenous gene. These data show that the AFP sequence, and not the IGFII P3 promoter we used, is suitable for targeting gene expression to malignant hepatic cells.
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PMID:Hepatoma cell-specific expression of a retrovirally transferred gene is achieved by alpha-fetoprotein but not insulinlike growth factor II regulatory sequences. 748 90

Erythroagglutinating phytohemagglutinin (E-PHA)-dependent isoforms of human alpha-fetoprotein (AFP) from cord blood were analyzed for their carbohydrate structures by two-dimensional electrophoresis with E-PHA combined with extended agarose gel electrophoresis or with affinity electrophoresis with concanavalin A or Allomyrina dichtoma lectin. By means of neuraminidase and/or beta-galactosidase treatment, AFP-P2 was identified as alpha 2-->6 disialo-AFP, AFP-P3 as having biantennary structures with alpha 2-->6 monosialylated galactose of the Mannose (Man) alpha 1-->6 arm, AFP-P4 as having alpha 2-->6 monosialylated galactose of the Man alpha 1-->3 arm, and AFP-P5 as disialo-AFP with alpha 2-->3 sialylated galactose of the Man alpha 1-->6 antenna with the alpha 2-->6 sialylated galactose of the other antenna. Desialylated AFP with the terminal galactose of the Man alpha 1-->6 antenna with or without the galactose of the other arm also had a migration of AFP-P4, and other hydrolytic intermediates without the terminal galactose of the Man alpha 1-->6 arm with and without the galactose of the other antenna had mobilities of AFP-P3s and AFP-P3, respectively. Thus, the present system of two-dimensional lectin affinity electrophoreses would provide a model for the determination of the sugar chain structure of glycoproteins.
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PMID:Characterization of E-PHA-reactive alpha-fetoprotein isoforms by two-dimensional lectin affinity electrophoresis. 751 Oct 99

We have investigated the differentiation potential of propagable cultured rat pancreatic duct epithelial cells after in vivo implantation in isogeneic Fischer-344 rats. Cells genetically labeled with Escherichia coli beta-galactosidase (lacZ) reporter gene were embedded in a mixture of collagen and Matrigel (basement membrane matrix) and implanted either subcutaneously or intraperitoneally. Tissues from the two locations were harvested 4 to 8 weeks later. The great majority of the lacZ-labeled epithelial cells colonizing both sites phenotypically resembled hepatocytes, although they demonstrated different degrees of hepatocytic differentiation. Less than 5% of lacZ-labeled cells formed ductular structures. The hepatocyte-like cells from the subcutaneous implantation site expressed mixed phenotypes of both hepatocyte and ductal cell, including the expression of alpha-fetoprotein, tyrosine amino-transferase, gamma-glutamyl transpeptidase, carbonic anhydrase II, and cytokeratin 19. In contrast, the hepatocyte-like cells colonizing the mesentery showed the phenotype of mature hepatocytes, including an abundant glycogen storage and a lack of alpha-fetoprotein and carbonic anhydrase II expressions. Neither acinar cell nor endocrine differentiation was seen. These findings demonstrate that pancreatic ductal cells can be the progenitor cell for transdifferentiated hepatocytes.
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PMID:Hepatocytic differentiation of cultured rat pancreatic ductal epithelial cells after in vivo implantation. 767 82

Recombinant adenoviruses are widely used for the transfer of foreign genes into various mammalian cells. However, the utilization of these vectors for cancer gene therapy requires the specific and efficient expression of the transferred gene in tumor cells. To obtain targeted expression in hepatoma cells, we constructed recombinant adenoviral vectors containing transcriptional elements from either the rat alpha-fetoprotein (AFP) or the human insulin-like growth factor II (IGFII) genes driving expression of the nuclear beta-galactosidase gene (nls lacZ). In vitro infection revealed that the AFP but not the IGFII transcriptional regulatory sequence controlled nls lacZ expression specifically in hepatoma cells. The same specificity was obtained in vivo in subcutaneous human hepatic tumors generated by engraftment of Huh7 hepatoma cells in nude mice as well as in primary liver tumors developed in rats and mice. No marker gene expression was detectable after AFP-nls lacZ gene transfer to normal rat liver parenchyma despite evidence for the presence of DNA encoding the nls lacZ gene. However, in vivo experiments with primary liver tumors in rats and mice also revealed that primary hepatoma cells were poorly infected by adenoviral vectors. Peritumoral and normal tissues were infected efficiently by adenoviral vectors. We conclude that hepatoma cell-specific expression of a transgene can be achieved with AFP regulatory sequences but that adenoviral vectors may not be the preferable vector for transferring genes in vivo in primary liver tumors.
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PMID:In vitro and in vivo hepatoma cell-specific expression of a gene transferred with an adenoviral vector. 886 51

Serum alpha-fetoprotein (AFP) is a glycoprotein of which the sugar chain is considered to show structural changes with malignancies. Microheterogeneity of the serum AFP carbohydrate structure was studied in samples from 35 patients with benign and malignant diseases. Sera were digested directly, extensively, and sequentially with sialidase. beta-galactosidase and beta-N-acetylhexosaminidase. Before and after digestion, sera were examined by means of lectin affinity electrophoresis using eight lectins. Relationships between AFP carbohydrate structures and liver diseases were elucidated by the lectin-reactive profiles and the effect of glycosidase digestion. More than 94% of the AFP carbohydrate structures found in patients with benign and malignant liver diseases were biantennary complex-type oligosaccharides. Changes in the AFP carbohydrate structures at the early stage of hepatocellular carcinoma revealed the addition of alpha 1-->6 fucose to the reducing terminal N-acetylglucosamine and monosialylated AFPs. In both advanced hepatocellular carcinoma and AFP producing extrahepatic malignancies, AFP carbohydrate structures were characterized as the further addition of beta 1-->4 N-acetylglucosamine and heterogeneity in the galactose and N-acetylglucosamine residues. Sequential glycosidase digestion and lectin affinity electrophoresis is useful for analysing the carbohydrate structures of serum glycoprotein.
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PMID:Comparison of carbohydrate structures of serum alpha-fetoprotein by sequential glycosidase digestion and lectin affinity electrophoresis. 889 7

We have used the yeast estrogen (YES) consisting of the human estrogen receptor and a reporter containing two estrogen response elements linked to the lacZ gene to evaluate the interaction between ovarian, phyto-, and synthetic estrogens with extracellular binding proteins. YES was incubated with charcoal-stripped human serum, human sex hormone-binding globulin, or human alpha-fetoprotein in the presence of concentrations of various estrogens that induced a 100% estrogenic response, as measured by beta-galactosidase activity. The activity of estradiol and coumestrol, a phytoestrogen, was reduced 75% with physiological levels of serum, sex hormone-binding globulin, or alpha-fetoprotein. The beta-galactosidase activity of genistein, another phytoestrogen, also decreased with extracellular proteins but to a lower extent than estradiol. In contrast, the activity of the synthetic estrogens diethylstilbestrol, kepone, and p,'p-DDD was only minimally reduced with extracellular proteins. These results indicate a potential fundamental difference in the interaction of estrogens from diverse sources with extracellular binding proteins. This suggests that the capacity for various estrogens to induce estrogen-associated responses is in part regulated by their affinity for extracellular bindings proteins.
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PMID:Differential interaction of natural and synthetic estrogens with extracellular binding proteins in a yeast estrogen screen. 891 58

The alpha-fetoprotein (AFP) gene is normally expressed in fetal liver and is transcriptionally silent in adult liver but overexpressed in human hepatocellular carcinoma (HCC). Here, we demonstrate that replication defective recombinant adenoviral vectors, containing the human AFP promoter/enhancer, can be used to express the Escherichia coli cytosine deaminase (CD) gene (AdAFPCD) and the beta-galactosidase gene (AdAF-PlacZ) in AFP-producing HCC cell lines. Expression of the CD gene by adenovirus from the AFP promoter/enhancer (AdAFPCD) induced cells sensitive to 5-fluorocytosine (5FC) in the AFP-producing cells but not in the AFP-nonproducing cells. Transduction by an adenoviral vector harboring an ubiquitous strong promoter and CD gene showed enzymatic activity and 5FC killing in all cell lines. When AdAFPlacZ was injected into the s.c. established hepatoma in vivo, expression of the beta-galactosidase gene was confined to AFP-producing HCC xenografts. Moreover, HCC xenografts regressed by transduction with AdAFPCD and subsequently with 5FC treatment in vivo. These findings suggest that utilization of the AFP promoter/enhancer in an adenoviral vector can confer selective expression of a heterologous suicide gene in hepatocellular carcinoma cells in vitro and in vivo.
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PMID:In vivo gene therapy for alpha-fetoprotein-producing hepatocellular carcinoma by adenovirus-mediated transfer of cytosine deaminase gene. 901 74

As human amniotic epithelial tissue is formed on about the eighth day after fertilization, human amniotic epithelial cells (hAEC) may have multipotency to differentiate into various organs, such as brain, heart, or liver. In this study, we showed evidence of the synthesis and excretion of albumin by hAEC, by immunostaining and enzyme-linked immunoassay. Reverse transcription-polymerase chain reaction (RT-PCR) and western blot analyses revealed the expression of albumin mRNA and protein, respectively. In addition, hAEC also demonstrated immunoreactivity to genetic markers of liver lineage, such as human serum albumin and alpha-fetoprotein. Transplanted hAEC to Scid mouse liver showed positive immunoreactivity to albumin and alpha-fetoprotein. Genetically modified cells containing the beta-galactosidase (LacZ) gene (AxCALacZ) were integrated in liver parenchyma. Human polymorphic gene analysis in Scid mouse liver after the implantation of hAEC showed that these Scid mouse livers obviously contained this human-specific gene until day 7 after the cell transplantation. As hAEC do not cause any acute rejection by allotransplantation, we conclude that hAEC may be useful as a transgene carrier to treat patients with inherited liver diseases.
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PMID:Human amniotic epithelial cells are promising transgene carriers for allogeneic cell transplantation into liver. 1080 43

Murine embryonic stem (ES) cells can replicate indefinitely in culture and can give rise to all tissues, including the germline, when reimplanted into a murine blastocyst. ES cells can also be differentiated in vitro into a wide range of cell types. We have utilized a liver-specific marker to demonstrate that murine ES cells can differentiate into hepatocytes in vitro. We have used ES cells carrying a gene trap vector insertion (I.114) into an ankyrin repeat-containing gene (Gtar) that we have previously shown provides an exclusive beta-galactosidase marker for the early differentiation of hepatocytes in vivo. beta-Galactosidase-positive cells were differentiated from I.114 ES cells in vitro. The identity of these cells was confirmed by the expression of the proteins alpha-fetoprotein, albumin, and transferrin and by the fact that they have an ultrastructural appearance consistent with that of embryonic hepatocytes. We propose that this model system of hepatic differentiation in vitro could be used to define factors that are involved in specification of the hepatocyte lineage. In addition, human ES cells have recently been derived and it has been proposed that they may provide a source of differentiated cell types for cell replacement therapies in the treatment of a variety of diseases.
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PMID:Hepatic differentiation of murine embryonic stem cells. 1174 Aug 61


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