Rh Ce Research Articles

Effect of 1-beta-D-arabino-furanosyl-cytosine (ara-C) induction of K562 cells on expression of Rh and other blood group active proteins.

K562 cells undergoing differentiation induced by 1-beta-D-arabino-furanosyl-cytosine (ara-C) were examined as a model for studying the biosynthesis and regulation of Rh and other blood group active membrane proteins. Untreated and ara-C-induced K562 cells were analysed for the expression of these proteins using monoclonal antibodies in combination with flow cytometry. The major membrane proteins glycophorins A and C remained unaltered upon induction by ara-C. The display of LFA-3 (CD58) and DAF (CD55) by uninduced K562 was one order of magnitude lower than that of the glycophorins; following ara-C treatment there was a 50% rise in LFA-3 but a modest decrease in the level of DAF expression. The expression by untreated K562 cells of Rh, Lutheran and Kell proteins as well as the Rh D antigen was low, whereas that of CD44 and band 3 protein was negligible. Following induction by ara-C the levels of Rh and Kell proteins rose up to 7- and 3.5-fold respectively, and there was an increase in RhD-antigen expression. In contrast, ara-C induction of K562 cells failed to augment their display of Lutheran, CD44 and band 3 proteins. Analysis of Rh transcripts following the purification and RT-PCR analysis of K562 mRNA showed that uninduced K562 cells contain two distinct mRNAs corresponding to Rh Ce (1.8 kb) and Rh D (3.5 kb). The apparent concentration of each mRNA increased following induction with ara-C. K562 plasma membranes also contained Rh polypeptides as determined by immunoblot analysis using anti-Rh polypeptide rabbit polyclonal sera raised to Rh synthetic peptides. A novel hybrid Rh transcript corresponding to exons 1-4 of RHD and exons 5-10 of RHCE has been cloned and sequenced from ara-C induced K562 cells, and may have arisen by general recombination between the RHD and RHCE genes.

Heteroduplex generator in analysis of Rh blood group alleles

We describe the use of heteroduplex analysis to enhance the resolution of different rhesus-derived (Rh) isotypes. Heteroduplex analysis of different domains of the Rh D and Rh CE loci can be performed to diagnose a variety of blood group incompatibilities. One application of this technique is the ability to test for fetal-maternal blood group incompatibilities during pregnancy. Several new serotype-specific sequence variations were discovered in the mapping of the Rh locus, and used in the construction of artificial heteroduplex generators (HGs). HGs facilitate the resolution of the Rh isotypes by electrophoretic methods.

Microstructure of RhCe particles on silica: Interactions between Ce and SiO 2

We have characterized the microstructure of Rh/Ce on SiO 2 after heat treatments in H 2 and O 2 using TEM, HREM, XPS, and EELS, focusing on the very stable structures formed after heating in H 2. After initial reduction at 600°C, Rh is present as 50- to 100-Å metal particles while the Ce forms a uniform amorphous film of Ce 3+ on the SiO 2. After oxidation at 600°C, Rh is oxidized to Rh 2O 3 and spreads over the SiO 2 surface while Ce forms small patches and large (>1000 Å) particles of crystalline CeO 2. After reduction of the oxidized microstructure at 600°C, Rh metal returns with a less uniform particle size distribution, while Ce is reduced to Ce 3+ and structures indicating strong interactions between Ce and Si are formed. Upon reduction in the presence of Rh, the CeO 2 particles are reduced to crystalline Ce 2Si 2O 7 as confirmed by HREM. The Ce silicate nucleates at Rh particles and spreads over the support as large thin (>1000 Å diameter and ≈50 Å thick) single-crystal patches. After reoxidation at 650°C, both Ce silicate (Ce 3+) and CeO 2 were identified using EELS chemical shifts, indicating that the crystalline silicate, once formed, is stable in oxygen. Ce on SiO 2 also showed interaction between Ce and Si, but no crystalline species formed after reduction and only small crystalline CeO 2 particles formed after oxidation. Thus, the formation of the Ce silicate and the oxidation of Ce to CeO 2 are catalyzed by Rh. This work represents the first direct evidence for the formation of a Ce silicate in this system, and the combined use of HREM, XPS, and micro-EELS permits chemical characterization of these structures.