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At least 145 records · Page 8Linked to original sources
PubMed1994

Structural features of mag, a gypsy-like retrotransposon of Bombyx mori, with unusual short terminal repeats.

Mag is a retrotransposon found as an insert in the Sericin 2 gene. It is present in a few copies--4 to 15--dispersed in the genome of different strains of Bombyx mori as well as in Bombyx mandarina. Flanked by a 5 bp target sequence with no sequence specificity, it is bordered by direct repeats of 77 nucleotides. Despite their unusual short size, these terminal repeats and their immediately adjacent sequences present all the signals necessary for transcription into genomic RNA and for reverse transcription. Mag contains two overlapping open reading frames which are organized as the gag and pol genes of retroviruses and encode putative nucleic acid binding peptide, protease, reverse transcriptase, RNase H and endonuclease in this order. Sequence comparison of these proteins places mag within the gypsy group of LTR retrotransposons next to the echinoderm element SURL.

Amino Acid Sequence↗
PubMed2002

Model-based comparison of maternal and foetal organ doses from (99m)Tc pertechnetate, DMSA, DTPA, HDP, MAA and MAG(3) diagnostic intakes during pregnancy.

Organ residence times were calculated for diagnostic intakes of (99m)Tc pertechnetate, 2,3-dimercaptosuccinic acid (DMSA), diethylene triamine penta-acetic acid (DTPA), hydroxymethylene diphosphonate (HDP), macroaggregated albumin (MAA) and mercapto-acetyltriglycine (MAG(3)) during the 1st and 3rd stages of pregnancy and used with the MIRDOSE3 pregnant female phantoms for generation of dose estimates. At stage 3 individual foetal organ doses were estimated via a surrogate phantom based on that for the new-born but with mean dose/cumulated activity ( S) values scaled for compatibility with foetal whole body S. Stage 1 or 3 whole foetus doses ranged from 5.2 to 0.77 microGy MBq(-1) respectively, analogous to current ICRP estimates for these agents using similar in vivo biodistribution model databases. Most stage 3 maternal and foetal organ doses were similar within a factor of 3, being higher in the foetus than the mother with pertechnetate, DTPA and MAG(3), and lower with DMSA, HDP and MAA. Doses were more uniformly distributed among foetal organs than in the mother. Placental transfer was greatest with pertechnetate, where dose to the stage 3 foetal thyroid was 60-140 microGy MBq(-1). With each agent there was more placental transfer in stage 3 than in stage 1, but doses to stage 1 whole foetus were always higher, with the contribution from the mother dominant. For DMSA, HDP and MAG(3) the maternal contribution to total foetal body dose exceeded 93% for both stages.

Animals↗
PubMed2000

Polyneuropathy attributes: a comparison between patients with anti-MAG and anti-sulfatide antibodies.

Thirty-two patients with a peripheral neuropathy and paraproteinemia were tested for IgM antibodies against myelin-associated protein (MAG) and sulfatide by means of enzyme-linked immunosorbent assay. Nine patients (28 %) had increased anti-sulfatide IgM antibodies and showed a chronic, slowly progressive, distally pronounced, and symmetric polyneuropathy with sensory to sensory-motor impairment, ataxia, hyporeflexia, and axonal involvement in electrophysiological studies. Ten patients (31 %) with increased anti-MAG antibodies had a similar, homogeneous polyneuropathy syndrome but presented with demyelinating features. A weak cross-reactivity between anti-MAG and anti-sulfatide antibodies was present in only three patients. In conclusion, although the two neuropathy groups clearly differed in their electrophysiological features, their clinical presentation was rather similar.

Aged↗
PubMed1994

Interactions of polyamines in the measurement of free magnesium concentration by mag-fura-2 and 31P-NMR.

Polyamines, particularly spermine, in physiological concentrations interact with mag-fura-2 and the mag-fura-2/Mg2+ complex, resulting in reduced values of free Mg2+ concentration. Similarly, polyamines interact with ATP and MgATP. Thus, free Mg2+ concentration, as measured by 31P-NMR or mag-fura-2, is underestimated in the presence of polyamines, particularly of spermine.

Adenosine Triphosphate↗
PubMed1986

Characterization of oligosaccharides that bind to human anti-MAG antibodies and to the mouse monoclonal antibody HNK-1.

In some patients with neuropathy and IgM M-proteins the M-proteins bind to a carbohydrate determinant that is shared by the CNS and PNS myelin-associated glycoprotein (MAG) and by several additional glycoproteins and 2 glycolipids in peripheral nerve. The HNK-1 mouse monoclonal antibody binds to the same glycoproteins and glycolipids as well as to a number of other neuronal adhesion molecules and to human natural killer cells. To isolate the epitope-bearing oligosaccharides from their respective glycoproteins we digested delipidated spinal cord and peripheral nerve with pronase. The resulting glycopeptides were fractionated by concanavalin A-Sepharose chromatography to yield tri- and tetraantennary-complex, biantennary-complex and high mannose-type glycopeptides. Glycopeptides bearing the antigenic determinant were identified by their ability to block binding of M-proteins and HNK-1 antibodies to MAG-coated microwells by enzyme-linked immunosorbent assay (ELISA). Blocking activity was detected in the tri- and tetraantennary glycopeptide fraction from both CNS and PNS. The blocking activity was destroyed by pretreatment of the isolated glycopeptides with mild acid hydrolysis. Further fractionation by gel filtration chromatography indicated that the reactive glycopeptides from peripheral nerve and spinal cord eluted in the same position. The data suggest that CNS and PNS MAG and other peripheral nerve glycoproteins share similar oligosaccharides, and that the M-proteins and HNK-1 bind to the same structures.

Animals↗
PubMed1991

The B-cells that express anti-MAG antibodies in neuropathy and non-malignant IgM monoclonal gammopathy belong to the CD5 subpopulation.

B-cells that express monoclonal IgM anti-MAG antibodies (M-protein) in a patient with neuropathy and non-malignant IgM monoclonal gammopathy were studied by flow cytometry to determine if they bear the CD5 cell surface antigen. The CD5+ antigen is expressed on a subpopulation of B-cells which has been implicated in the secretion of autoantibodies and development of B-cell chronic lymphocytic leukemia (B-CLL). The monoclonal anti-MAG antibodies secreting B-cells were identified by a mouse monoclonal antibody to M-protein idiotype. Cytofluorometric analysis revealed that approximately 62% of the idiotype-positive B-lymphocytes expressed the CD5 antigen. The result of this study indicate that monoclonal anti-MAG antibodies may be secreted by CD5+ B-cells, and that B-cells in some cases of non-malignant IgM monoclonal gammopathy may be phenotypically similar to B-CLL cells.

Antibodies↗
PubMed2006

Severe cranial nerve involvement in a patient with monoclonal anti-MAG/SGPG IgM antibody and localized hard palate amyloidosis.

We report a patient with severe cranial polyneuropathy as well as sensory limb neuropathy. Biclonal serum IgM-kappa/IgM-lambda gammopathy was found and serum anti-myelin-associated glycoprotein (MAG)/sulfoglucuronyl paragloboside (SGPG) IgM antibody was also detected. Immunofluorescence analysis of a sural nerve biopsy specimen revealed binding of IgM and lambda-light chain on myelin sheaths. No amyloid deposition was detected in biopsied tissues except for the hard palate, suggesting that the amyloidosis was of the localized type and had no relation to the pathogenesis of cranial neuropathy. Our observations indicate that the anti-MAG/SGPG IgM antibody may be responsible for this patient's cranial polyneuropathy, which is a rare manifestation in anti-MAG/SGPG-associated neuropathy.

Amyloid↗
PubMed2006

Hairy cell leukaemia complicated by anti-MAG paraproteinemic demyelinating neuropathy: resolution of neurological syndrome after cladribrine treatment.

Hairy cell leukaemia (HCL) occasionally displays a monoclonal gammopathy, yet the association of HCL with paraproteinemic demyelinating neuropathy (PDN) has not been reported. We describe a HCL case complicated by PDN and high titers of monoclonal IgM against myelin associated glycoprotein (MAG). Heavy and light chains of the patient's anti-MAG monoclonal protein were consistent with those expressed by HCL cells. After treatment with cladribrine, remission of HCL strictly paralleled disappearance of the IgM monoclonal protein and of the serum anti-MAG activity, and led to PDN clinical and electrophysiological improvement. Purine analogs may represent a choice in IgM PDN associated with lymphoproliferative disorders.

Aged↗
PubMed2002

Tomacula in MAG-deficient mice.

The pathogenesis of tomacula in mice with a null mutation of the myelin-associated glycoprotein (MAG) gene is not well understood. This study, using a novel teased nerve fiber technique, demonstrates that tomacula in MAG-deficient mice are formed by redundant myelin infoldings and outfoldings in the paranodal regions as early as 4 weeks after birth and increase in size and frequency with age. Although tomacula show degenerative changes with increasing age, there was no significant evidence of demyelination/remyelination. Longitudinal sections of normal teased nerve fibers show early redundant myelin foldings in externally normal paranodal regions. These data and the absence of internodal tomacula support a role for MAG in the maintenance of myelin at the paranodal regions.

Animals↗
PubMed1981

Normal neutrophil function in human renal allograft recipients receiving Minnesota anti-lymphoblast globulin (MAG).

Equine anti-human lymphoblast globulin (MAG) used in combination with other immunosuppressive agents did not impair chemotaxis, phagocytosis, nitroblue tetrazolium (NBT) reduction or halogenation by peripheral blood neutrophils (PMN) from seven human recipients of cadaver renal allografts. MAG was given to the allograft recipients following transplantation, and the dosage was determined each day by quantitation of peripheral blood T and B lymphocytes. No deposition of immunoglobulin or complement on the recipient's PMN was detected by indirect immunofluorescence. Chemotaxis of PMN was determined in blind-well chambers, and phagocytosis of opsonized zymosan was quantitated by spectrophotometric measurement of solubilized formazan, and halogenation was measured by quantitating the incorporation of 125I into PMN that had phagocytosed opsonized zymosan. Chemotaxis, phagocytosis, NBT reduction, and halogenation by neutrophils from patients receiving MAG, prednisone and azathioprine were not impaired.

Adult↗
PubMed2000

Long-term prognosis of neuropathy associated with anti-MAG IgM M-proteins and its relationship to immune therapies.

Many data point to a pathogenetic role for IgM antibodies to the myelin-associated glycoprotein (MAG) in the neuropathy associated with IgM monoclonal gammopathy, supporting the use of immune therapies in affected patients. Almost 50% of patients have been reported to improve with these therapies, but the effect of treatment on the long-term prognosis of the neuropathy remains unclear. We analysed the outcome of 25 of the 26 patients (mean age at entry 65 years, range 45-85 years) with neuropathy and high anti-MAG IgM, first examined by us between 1984 and 1994. By January 1999, after a mean follow-up of 8.5 years (range 2-13 years) and a mean duration of neuropathy symptoms of 11.8 years (range 3-18, >10 years in 16), 17 patients (68%) (aged 58-84 years, mean 73.4) were alive, while eight (32%) (aged 69-78 years, mean 73.1) had died 3-15 years (mean 10.6) after neuropathy onset; in none of them was death caused by the neuropathy, although in three it was possibly related to the therapy for the neuropathy. By the time of last follow-up or patients' death, 11 patients (44%) were disabled by severe hand tremor, gait ataxia or both. The disability rates at 5, 10 and 15 years from neuropathy onset were 16, 24 and 50%, respectively. Of the 19 patients treated during the follow-up for 0.5-11 years (mean 4 years) with various immune therapies, five reported a consistent and four a slight improvement in the neuropathy (total 47%) after one treatment or more, but in only one patient was improvement persistent throughout, to the end of follow-up. In 10 patients (53%), severe adverse events, possibly related to therapy, occurred during treatment and were considered responsible for the patient's death in three. The neurological impairment did not differ between treated and untreated patients at the end of a similar follow-up. Our findings indicate that (i) the majority of patients with neuropathy and anti-MAG IgM have a favourable prognosis even after several years, and (ii) current immune therapies, though temporarily effective in half of the patients, are associated with considerable side effects which limit their prolonged use and efficacy, suggesting that until more effective or safer therapies become available, they should probably be reserved for patients impaired in their daily life or in a progressive phase of the disease.

Aged↗
PubMed1989

Reproducibility of quantitative 99Tcm-MAG 3 measurements in rats.

Repetitive quantitative renal extraction studies of 99Tcm-MAG 3, performed in nine rats, demonstrated excellent reproducibility of successive measurements. These results are better than with 99Tcm-DTPA, due to the higher renal extraction of the 99Tcm-MAG 3. The % of renal uptake 10 min after the injection was not influenced by the elapsed time between the end of the 99Tcm-MAG 3 preparation and its i.v. administration.

Animals↗
PubMed1997

Preparation of a multiple antigen glycopeptide (MAG) carrying the Tn antigen. A possible approach to a synthetic carbohydrate vaccine.

The glycosidic tumor-associated Tn antigen was conjugated to a lysine backbone containing a helper T-cell epitope in order to activate immune responses specific for some types of carcinomas. As opposed to traditional protein conjugates, this multiple antigen glycopeptide (MAG) offers the advantages of the lack of immunogenicity of the polylysine core and of accurate chemical definition. The MAG construction was assembled by conventional solid-phase peptide synthesis. The analysis of its antigenicity demonstrated that the Tn antigen on the MAG is recognized by Tn-specific monoclonal antibodies.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1992

Comparison of the N-linked oligosaccharide structures of the two major human myelin glycoproteins MAG and P0: assessment of the structures bearing the epitope for HNK-1 and human monoclonal immunoglobulin M found in demyelinating neuropathy.

The epitope for HNK-1 and patient's monoclonal autoantibodies in demyelinating polyneuropathy associated with immunoglobulin M gammopathy is borne by different types of N-linked oligosaccharide structures in human P0 and myelin-associated glycoprotein (MAG). Fourteen glycopeptide fractions bearing different oligosaccharide structures were obtained from either MAG or P0 glycopeptides by serial lectin affinity chromatography on concanavalin A-Sepharose, Phaseolus vulgaris erythrophytohemagglutinin-agarose, Pisum sativum agglutinin-agarose, and Phaseolus vulgaris leucophytohemagglutinin-agarose. As shown by dot-TLC plate immunostaining, the same MAG and P0 glycopeptide fractions were recognized by HNK-1 and patient's immunoglobulin M, confirming that these antibodies display similar specificities. The antigenic carbohydrate was present in glycopeptide fractions that either interact with Pisum sativum agglutinin-agarose or were bound by Aleuria aurantia agglutinin-digoxigenin, indicating that these structures contained alpha(1-6)fucose residues. This study demonstrates that the L2/HNK-1 epitope is borne mainly or even exclusively by N-linked oligosaccharide structures alpha(1-6)fucosylated in the core.

Antibodies, Monoclonal↗
PubMed2004

Nogo-66 and myelin-associated glycoprotein (MAG) inhibit the adhesion and migration of Nogo-66 receptor expressing human glioma cells.

Malignant gliomas are common and aggressive brain tumours associated with significant morbidity and mortality. We showed in this report that substratum adherence and migration by human U87MG glioma cells in culture were significantly attenuated by the extracellular domains of Nogo-A (Nogo-66) and the myelin-associated glycoprotein (MAG). U87MG cells contained significant amounts of endogenous Nogo-66 receptor (NgR), and treatment of the cells with phosphatidylinositol-specific phospholipase C (PI-PLC) or NgR antibodies resulted in an increase in their ability to adhere to, or migrate through, Nogo-66- and MAG-coated substrates. Nogo-66 and MAG may therefore modulate glioma growth and migration by acting through the NgR, a phenomenon that has potential therapeutic implications.

Antibodies↗
PubMed1985

Human monoclonal anti-MAG antibody and anti-Leu 7 recognise shared antigenic determinants in peripheral nerve and spinal cord.

Anti-Leu 7 monoclonal antibody (MAB), a marker of natural killer cells, and a human MAB to myelin-associated glycoprotein (MAG) from a patient with a demyelinating neuropathy specifically stained Schmidt-Lanterman incisures, paranodal and periaxonal regions in peripheral nerve myelin by immunocytochemistry on thin plastic sections, while compact myelin was labelled in paraffin-embedded material. Preabsorption studies indicated that the antigen recognised was a MAG epitope shared by MAG and Leu 7. In spinal cord both MABS bound to oligodendrocytes and a subclass of anterior horn cells. Our findings support the hypothesis that shared antigens between the nervous and the immune systems do exist in situ, which may be important in the pathogenesis of demyelinating neuropathies with monoclonal gammopathies.

Animals↗
PubMedDate not supplied

Sensitisation to the lipid-binding apolipophorin allergen Der p 14 and the peptide Mag-1.

BACKGROUND: The IgE-binding peptides Mag 1 and Mag 3 and the high-molecular-weight protein M-177 have been identified as parts of the apolipophorin-like group 14 house dust mite allergen. By analogy with the homologous insect proteins, apolipophorins are hydrophobic proteins found in lipid bodies and lipid transport particles. This explains why they degrade and are poorly represented in extracts. METHODS: We have examined the T cell stimulation induced by a 341-residue recombinant Der p 14 peptide equivalent to the Mag 1 polypeptide examined by others. RESULTS: Peripheral blood mononuclear cells from both allergic and non-allergic donors responded strongly in in vitro proliferation assays to the Der p 14 peptide to induce markedly more (3)H-thymidine incorporation than Der p 2 and the release of Th2 cytokines. CONCLUSIONS: The apolipophorin-like group 14 allergens, despite their predicted hydrophobicity and lipid-binding activity, can induce high IgE responses and T cell stimulation. They appear to be important mite allergens unsuited to representation by aqueous extracts of mites.

Allergens↗
PubMed1995

Anti-MAG antibody-associated polyneuropathies: improvement following immunotherapy with monthly plasma exchange and IV cyclophosphamide.

Treatment outcomes of sensory-motor polyneuropathies associated with anti-myelin-associated glycoprotein (MAG) antibodies have varied even with relatively intensive immunosuppression. We used plasma exchange and cyclophosphamide to treat four patients with anti-MAG antibody-associated polyneuropathies whose symptoms had progressed in the preceding year. Treatment courses consisted of five to seven monthly regimens of plasma exchange on 2 consecutive days followed by intravenous cyclophosphamide (1 g/m2). Effects of treatment were quantitatively measured with hand-held dynamometry. All four patients showed improvement in both strength and sensation in the 5 to 24 months after treatment. We conclude that selected patients with sensory-motor polyneuropathies associated with high-titer serum IgM autoantibodies against MAG may have quantitative and useful functional improvement after immunotherapy. The improvement continues after completion of treatment and may persist for 1 to 2 years or longer.

Antibodies↗