Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026916 (MAC)
 5,226 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Exponentially growing cultures of Mycobacterium avium complex serovar 4 were treated with 2-deoxy-D-glucose (2-DDG) and incubated with radiolabelled components which incorporate into the serovar-specific glycopeptidolipids (GPL) associated with the L1 layer. Following treatment with the drug, radiolabelled lipids were extracted from the mycobacteria and examined by thin-layer chromatography, high performance liquid chromatography and autoradiography to determine the percent distribution of radioactivity in the GPL and other related lipids. Treatment of serovar 4 with 2-DDG resulted in a dose-dependent inhibition of GPL biosynthesis, as judged by a reduction in the incorporation of radiolabelled phenylalanine, mannose and methionine into the GPL. In addition, a concomitant accumulation of at least two phenylalanine-containing lipopeptides was observed in cells treated with 2-DDG. Cultivation of serovar 4 in the presence of 2-deoxy-D-1,2-(3)H-glucose did not result in internal radiolabelling of the GPL, indicating that 2-DDG was not being incorporated into the GPL as an analogue of mannose, but rather was acting as a metabolic inhibitor of GPL biosynthesis.
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PMID:Inhibition of glycopeptidolipid synthesis resulting from treatment of Mycobacterium avium with 2-deoxy-D-glucose. 194 32

Internal radiolabelling procedures were used to radiolabel the oligosaccharide determinant of the glycopeptidolipids (GPL) from serovars 4 and 20 of the Mycobacterium avium complex. Mycobacteria were cultured in the presence of [6-3H]fucose, [2-3H]mannose or [methyl-3H]methionine, after which radiolabelled native lipid was extracted and distribution of radioactivity in native and deacetylated lipid was determined by thin-layer chromatographic methods. Incorporation of radiolabel was confirmed by examining acid hydrolysates of purified GPL for 3H-labelled sugars on cellulose thin-layer plates. Least incorporation of radiolabel into GPL was observed with [6-3H]fucose, whereas better incorporation was obtained with [2-3H]mannose and [methyl-3H]methionine. Use of [methyl-3H]methionine resulted in the radiolabelling of the methylated sugars in both the oligosaccharide determinant and the 3,4-di-O-methylrhamnose located at the terminus of the peptide core. Use of [2-3H]mannose resulted in the incorporation of radioactivity into the oligosaccharide determinant as 2-O-methylfucose, found in the GPL of both serovars 4 and 20. GPL radiolabelled with [2-3H]mannose were subsequently examined in macrophage cultures and found to be relatively inert to degradation by those phagocytic cells. These results substantiate earlier findings with the GPL of serovar 20 and indicate that these mycobacterial components may play a role in pathogenesis.
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PMID:Radiolabelling of Mycobacterium avium oligosaccharide determinant and use in macrophage studies. 248 34

Nitrous oxide administration may limit DNA synthesis by inactivating methionine synthetase, and may thus hamper the repair of an injured organ such as the liver. To test this possibility, we pretreated rats with phenobarbital and exposed them to 0.3 MAC halothane in 9% oxygen for 46 min, followed immediately and again 24 hr later by 70% nitrous oxide (0.25 MAC) at an FIO2 of 0.30 for 2 hr. The results from this group were compared with an anesthetic control group in which 0.35% isoflurane (0.25 MAC) was substituted for the nitrous oxide. Additional groups were given a third exposure to nitrous oxide or isoflurane 48 hr after the halothane exposure. All rats were killed 24 hr after their last anesthetic exposure. A second (nonanesthetic) control group of phenobarbital-pretreated rats received 0.3 MAC halothane in 9% oxygen for 46 min and no anesthetic thereafter. They were killed 24, 48, or 72 hr later. Histologic changes in the livers of rats did not differ among the groups given nitrous oxide, isoflurane, or no additional anesthetic after exposure to halothane alone. Thus neither nitrous oxide nor isoflurane appears to hinder the repair of hepatic injury produced by halothane in the hypoxic rat model.
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PMID:Nitrous oxide does not hinder the repair of halothane-induced hepatic injury in the rat. 399 7

A method has been established which isolated polysomes from the lysozyme/EDTA-shocked cyanobacterium, Nostoc sp. MAC. In a typical preparation the total recovery of RNA as polysomes was 83%, in which 77% of the polysome fraction was present at sizes greater than 5-mers and 23% as 2-4-mers. Messenger RNA isolated from such a preparation of polysomes produced a 10-fold stimulation in the incorporation of [35S]methionine into polypeptides by a cell-free system of Escherichia coli. The in vitro-synthesized polypeptides were analysed on an SDS-polyacrylamide gradient gel together with in vivo-labelled proteins of Nostoc sp. MAC: seven polypeptides co-migrated with the in vivo-synthesized products. This is the first report of the expression of cyanobacterial messenger RNA in a heterologous cell-free system from E. coli; the efficiency of the system is discussed.
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PMID:Isolation of polysomes from Nostoc sp. MAC and translation of messenger RNA in a heterologous cell-free system. 641 28

Our aim was to measure calpain protease activity during increases in cytosolic free calcium (Ca2+i) after addition of extracellular ATP. The calpain protease substrate t-butoxycarbonyl-Leu-Met-7-amino-4-chloromethylcoumarin was synthesized. Nonfluorescent t-butoxycarbonyl-Leu-Met-7-amino-4- chloromethyl-coumarin diffuses into the cell where it is conjugated to glutathione forming t-butoxycarbonyl-Leu-Met-7-amino-4-methylcoumarin glutathione conjugate (Boc-Leu-Met-MAC-SG). The nonfluorescent, membrane impermeant Boc-Leu-Met-MAC-SG accumulates in the cell. Intracellular proteolytic hydrolysis of Boc-Leu-Met-MAC-SG releases and unquenches the fluorescence of MAC-SG. Intracellular fluorescence of MAC-SG was quantitated in single, cultured rat hepatocytes using digitized video fluorescent microscopy. Enhancement of intracellular fluorescence generation by increases in Ca2+i and inhibition by a calpain inhibitor indicated the probe was a calpain substrate. After addition of ATP, calpain protease activity increased to 156 +/- 13% of basal concurrent with a 3-fold rise of Ca2+i for 2-4 min. Thereafter, Ca2+i decreased to values of 1.5-fold above basal and protease activity returned to normal. Incubation of cells in Ca(2+)-free buffer abolished the rise in Ca2+i and calpain protease activity. Calpain protease activity increases concomitantly with increases of Ca2+i supporting the hypothesis that calpain proteases participate in Ca(2+)-mediated signal transduction.
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PMID:Calpain activity increases in hepatocytes following addition of ATP. Demonstration by a novel fluorescent approach. 822 86

Transforming growth factor-beta 1 (TGF-beta 1) selectively modulates hematopoietic cell proliferation. The proliferation of FDC-P1 clone MAC-11, a factor-dependent murine myeloid progenitor cell line, was inhibited differentially by TGF-beta 1: strongly in macrophage colony-stimulating factor (M-CSF), mildly in interleukin-3, and not at all in granulocyte-macrophage-CSF (GM-CSF). Flow cytometry and Western blots showed an unexpected increase in expression of FMS, the receptor for M-CSF, in response to TGF-beta 1. Metabolic labeling with 35S-methionine showed that synthesis of FMS protein accelerated in response to TGF-beta 1, whereas its degradation was unaffected. Northern analyses showed a rapid increase in c-fms RNA after the addition of TGF-beta 1. TGF-beta 1 did not affect kinase activity, cellular phosphotyrosine response, or internalization of FMS. However, TGF-beta 1 inhibited the induction by M-CSF of c-myc RNA analyzed on Northern blots and protein detected by radioimmuno-precipitation. TGF-beta 1 did not affect induction of c-myc expression by GM-CSF or induction of c-fos or c-jun by M-CSF. Therefore, FMS and the GM-CSF receptor induce c-myc via signal transduction pathways that differ in that only the former is inhibited by TGF-beta 1. This inhibition may account for the selective growth regulation by TGF-beta 1.
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PMID:Mechanism of differential inhibition of factor-dependent cell proliferation by transforming growth factor-beta 1: selective uncoupling of FMS from MYC. 849 Jan 68

Twenty-two methionine-containing di- to octapeptides were evaluated for their ability to be a source of methionine to support protein accretion in C2C12 myogenic and MAC-T bovine mammary epithelial cells. The cell cultures were incubated for 72 h at 37 degrees C in a humidified environment of 90% air: 10% CO2 for C2C12 cells or 95% air: 5% CO2 for MAC-T cells. The basal medium contained methionine-free Dulbecco's modified Eagle's medium and 6% desalted fetal bovine serum. Treatments included basal medium, the basal medium supplemented with one of the 22 methionine-containing peptides, or the basal medium supplemented with free L-methionine. Methionine-containing peptides with the exception of glycylmethionine and prolylmethionine in C2C12 cells were able to support protein accretion with responses ranging from 29.1 to 123.3% of the response of L-methionine. Dipeptides with methionine at the N-terminus promoted greater (P < 0.0001) protein accretion than dipeptides with methionine at the C-terminus. Stimulation of protein accretion by seven pairs of dipeptides with methionine at either the C- or the N-terminus was linearly (P < 0.0001) related to the hydrophobicity of the dipeptides. These results indicate that C2C12 myogenic and MAC-T mammary epithelial cells have the ability to utilize methionine-containing peptides as sources of methionine to support protein accretion.
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PMID:Methionine-containing peptides can be used as methionine sources for protein accretion in cultured C2C12 and MAC-T cells. 855 6

We have shown previously that MACT-T and C2C12 cells utilize methionine-containing di- to octapeptides as methionine sources for protein accretion and cell proliferation in the presence of 60 mL/L desalted fetal bovine serum. In this study, serum factors that may regulate the use of peptides as amino acid sources in C2C12 and MAC-T cells were examined. The basal media contained methionine-free Dulbecco's modified Eagle's medium supplemented with 4.0 mL/L bovine serum lipids, 10 mL/L chemically defined lipid concentrate, bovine insulin (1 mg/L), 30 mL/L low protein serum replacement (LPSR-1) or 60 mL/L desalted animal serum. Treatment media included basal media supplemented with no methionine, L-methionine, or one of the methionine-containing peptides. L-Methionine promoted protein and DNA accretion (P < 0.05) in the presence of desalted animal sera, insulin or LPSR-1. Methionine-containing peptides also promoted protein and DNA accretion (P < 0.05) in the presence of desalted animal sera or LPSR-1, but not with insulin, except methionylleucine. In a cell-free medium, fetal bovine serum hydrolyzed peptides to varying degrees. We conclude that animal sera contain one or more factors that regulate utilization of peptides as amino acid sources for C2C12 and MAC-T cells.
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PMID:One or more serum factors promote peptide utilization in cultured animal cells. 952 38

The male accessory glands (MAGs) of Leptinotarsa decemlineata produce an 8kDa peptide, designated Led-MAGP, that is recognized by monoclonal antibody MAC-18. The site of synthesis, amino acid sequence and the gene encoding this peptide have been documented ([Smid and Schooneveld, 1992][Smid et al., 1997]). The primary structure is homologous to the N-terminal hexa-repeat section of the chicken prion protein ([Harris et al., 1991]). The biological function of the Led-MAGP has yet to be determined. For further research, large amounts of Led-MAGP is required, both for the production of a more specific antiserum, as well as for application in bio-assays. This paper describes the expression of Led-MAGP in insect cells infected with recombinant baculovirus, and the production of a polyclonal antibody against this recombinant peptide. The peptide was expressed under the control of the polyhedrin promotor. The resulting product was HPLC-purified, and analysis on Western blots immuno-labelled with MAC-18 confirmed that the correct peptide was produced. Purified recombinant peptide was also analyzed by Edman degradation and mass spectrometry; this indicated that it was N-terminally blocked and that the methionine residue at position 7 was oxidized. Large scale production resulted in the formation of aggregations of Led-MAGP, nevertheless a substantial proportion remained in a soluble state and could be harvested. A polyclonal antiserum encoded #87 was produced against recombinant Led-MAGP and its specificity was tested on Western blots of authentic peptide and on LM and EM sections of MAGs. All labelling results were equal to those obtained after MAC-18 labelling. However, antiserum #87 proved to be superior compared to MAC-18, since it recognizes the MAG peptide in normally fed, sexually active males, whereas MAC-18 labelling can only be accomplished after 7 days of starvation of the males. Therefore, the new antiserum #87 enables us to study the transfer dynamics of the Led-MAGP on histological sections.
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PMID:Expression of a male accessory gland peptide of Leptinotarsa decemlineata in insect cells infected with a recombinant baculovirus. 1276 59

Two series of 1,4-bis(2-amino-ethylamino)anthraquinone-amino acid conjugates (BACs), ametantrone (AT)-amino acid conjugates (AACs) and mitoxantrone (MX)-amino acid conjugates (MACs), were designed and synthesized. The DNA binding of BACs was evaluated by DNA thermal denaturation experiment. In the series, the methionine-substituted BACs had the weakest DNA binding, while the lysine-substituted BACs had the highest T(m) values. The abilities of BACs to inhibit the growth of MCF-7, NCI-H460, SF-268, and PC-3 cell lines were determined. l-Met-MAC 16 and l-Lys-MAC 20 were the most potent growth inhibitors. MAC 16 was more cytotoxic than MX, whereas the T(m) of MAC 16 was much lower than that of MX. In contrast to MAC 16, l-Lys-MAC 20 demonstrated higher T(m) than MX. These data suggested that Met-BACs possessed a different pharmacological profile, in which the ability to stabilize DNA is not parallel to the ability to kill cancer cells, from that of AT and MX. The primary mechanism of cytotoxicity for MAC 16 was most likely through TOP2 poisoning. Therefore, MAC 16 may provide a lead for the development of novel generations of anthraquinone-type antitumor agents.
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PMID:Synthesis, DNA binding, and cytotoxicity of 1,4-bis(2-amino-ethylamino)anthraquinone-amino acid conjugates. 1796 28


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