Core 2 Research Articles

ChemInform Abstract: N-p-Nitrobenzyloxycarbonyl Galactosamine Imidate as a Glycosyl Donor for the Efficient Synthesis of Mucin Core-2 Analogue.

Abstract An efficient synthesis of the mucin core-2 analogue 1a Download : Download high-res image (83KB) Download : Download full-size image Figure 1 . This C-2 position is blocked for commonly occurring α(1,2)- l -fucosyltransferase. was accomplished using N-p-nitrobenzyloxycarbonyl(PNZ)-protected trichloroacetimidate 4 Download : Download high-res image (134KB) Download : Download full-size image Scheme 2 . Reagents and conditions: (i) 4 (1.5 equiv), TESOTf (0.24 equiv), CH2Cl2, 4 A molecular sieves, rt, 15 min, 89%; (ii) Na2S2O4 (8 equiv), MeCN:EtOH:H2O (v/v/v 1:1:1), 10 min; (iii) Ac2O–MeOH; (iv) 75% acetic acid, 45 °C, 2 h, 90%; (v) 80% acetic acid, 40 °C, 2 h, 92%; (vi) 4 (1.2 equiv), TESOTf, CH2Cl2, −65 °C, 1 h, 78%; (vii) pyridine–Ac2O, DMAP; (viii) 4 (1.2 equiv), BF3·Et2O (0.5 equiv), CH2Cl2, −60 °C, 30 min, 82%. as a novel glycosyl donor.

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Flow cytometric detection of hepatitis C virus antigens in infected peripheral blood leukocytes: binding and entry.

We designed two synthetic-core-specific peptides core 1 (C1) and core 2 (C2), and an E1-specific peptide (E1). We produced specific polyclonal antibodies against these peptides and used the antibodies for detection of HCV antigens on surface and within infected peripheral blood leukocytes. Peripheral blood from a healthy individual who tested negative for HCV RNA was incubated with HCV type 4 infected serum for 1 h and 24 h at 37 degrees C. Cells were stained by direct and indirect immunofluorescence and measured by flow cytometry. After 1 h of incubation, antibodies against C1, C2, and E1 detected HCV antigens on the surface of 27%, 26% and 73% of monocytes respectively, while 10%, 5% and 9% of lymphocytes were positive with anti-C1, anti-C2 and anti-E1 respectively. Only 1-3% of granulocytes showed positive staining with anti-C1, anti-C2 and anti E1 antibodies. After 24 h of incubation, we found no surface staining with anti-C1, anti-C2 or anti-E1. Direct immunostaining using anti-C2 could not detect intracellular HCV antigens, after 1 h of incubation with the virus, while after 24 h of incubation, 28% of infected cells showed positive staining. Only plus strand RNA was detectable intracellularly as early as 1 h after incubation, and remained detectable throughout 48 h post-infection. Interestingly, minus RNA strand could not be detected after 1 h, but became strongly detectable intracellularly after 24 h post-infection. Monocytes and lymphocytes are the preferred target cells for HCV infection in peripheral blood leukocytes. Our specific anti-core and anti-E1 antibodies are valuable reagents for demonstration of HCV cell cycle. Also, HCV is capable of infecting and replicating in peripheral blood mononuclear cells as confirmed by detection of minus strand HCV RNA as well as intracellular staining of core HCV antigen.

Sialylated core 1 based O-linked glycans enhance the growth rate of mammary carcinoma cells in MUC1 transgenic mice.

The MUC1 mucin, found on the luminal surface of simple epithelial cells is upregulated and aberrantly glycosylated in many carcinomas particularly breast and ovarian. MUC1 expressed by normal mammary epithelial cells, carries core 2 glycans but in breast carcinomas the simple core 1 based glycans are added. The binding of the monoclonal antibody SM3 to its peptide epitope in the tandem repeat of MUC1 is blocked by the branched core 2 glycans found on MUC1 expressed by normal cells. Thus SM3 does not bind to MUC1 expressed by normal mammary epithelial cells but reacts with more than 90% of breast carcinomas, suggesting that the loss of at least some core 2 glycans is a very common event in breast carcinogenesis. To determine if the change in glycosylation observed in breast carcinomas confers an advantage to cancer cells, murine mammary carcinoma cell lines were developed that express MUC1 carrying core 2 or core 1 linked glycans. The in vivo growth rate in wild-type and nude mice were identical regardless of the O-glycosylation patterns. However, the tumors that grew out of wild-type mice lost most of their MUC1 expression. In contrast, in MUC1 transgenic mice, where expression of MUC1 was retained by the tumor, a striking difference in growth rate was observed. In these mice, cells expressing core 1 glycans grew significantly faster than cells expressing core 2 glycans. These data suggest that MUC1 transgenic mice are more tolerant to core 1 expressing tumors than to tumors expressing core 2.

ChemInform Abstract: First Total Synthesis of Sialylated and Sulfated Lewisx Mucin Core 2 Structures as Potential Tumor Associated Antigens.

Abstract Two branched Core 2 structures, (3-O-SO3Na)Galβ1→4(Fucα1→3)GlcNAcβ1→6(NeuAcα2→3Galβ1→3)GalNAcαOMe (1) and its positional isomer NeuAcα2→3Galβ1→4(Fucα1→3)GlcNAcβ1→6(3-OSO3Na-Galβ1→3)GalNAcαOMe (2), were chemically synthesized for the first time as potential tumor associated antigens.