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R O'Brien

Publications and source records attributed to R O'Brien.

67 records · Page 4Linked to original sources
PubMedDate not supplied

Peptide sequences of T-cell receptor delta and gamma chains are identical to predicted X and gamma proteins.

Although most mature peripheral T lymphocytes express a major histocompatibility complex restricted, CD3-associated, antigen receptor (TCR) which has been well characterized, some T cells carry a different CD3-associated heterodimer on their surface. One of the two disulphide-linked chains of this putative second receptor, which in mice has relative molecular mass (Mr) 35,000 (35K), has been identified as a product of the group of gamma genes. The other chain, termed delta (Mr 45K in mice), is not as well characterized. Although gamma/delta-bearing cells are a minor subset among peripheral T lymphocytes, they are the only CD3+ cells in the thymus early in ontogeny. Taking advantage of these kinetics, we have generated gamma/delta-bearing hybridomas, using a new TCR alpha chain-negative variant of the AKR thymoma BW5147 as tumour parent, fetal thymocytes as normal cell partners, and an anti-CD3 monoclonal antibody (mAb) as screening reagent. Gamma and delta chains from one of these hybrids have been purified and partially sequenced. The sequences obtained indicate that delta is indeed identical to the polypeptide encoded by the recently described gene X, as suggested by Chien et al.

Amino Acid Sequence↗
PubMedDate not supplied

Proton MR spectroscopy of experimental radiation-induced white matter injury.

We studied the spectroscopic appearance of radiation-induced myelinolysis in cats to understand the characteristics of proton MR spectroscopy of demyelinating disorders. Eight cats received 5,000 rads to a 1.5 x 1.5 cm area of the right cerebral hemisphere. Eight to 9 months after irradiation, a gross area of abnormal postcontrast enhancement and/or high MR signal intensity was detected in the irradiated hemisphere of six of the eight cats. Proton spectra of a 1.0 cm3 voxel in the affected region demonstrated depressed N-acetyl aspartate/creatine-phosphocreatine and N-acetyl aspartate/choline-containing compound peak ratios compared with the contralateral non-irradiated brain in all cats. Elevated amino acid resonances in the 2.0-2.5 ppm range were not consistently seen in irradiated zones of the brain with pathologic findings of demyelination. In vivo proton MR spectroscopy may show differences between irradiated brain and nonirradiated brain even when histopathologic lesions are not apparent yet.

Amino Acids↗
PubMedDate not supplied

Spectral characteristics of human leukocytes and their relevance to automated cell identification. III. Eosinophils, neutrophils and lymphocytes.

The spectral characteristics of various normal cell types from human blood were examined in respect to an automated, rapid-flow photometric identification system after staining for peroxidase activity. It was found that a plot of light loss against light scatter gave a separation of eosinophils, neutrophils and lymphocytes comparable in accuracy to visual separations. This staining was not useful for the segregation of monocytes and basophils, for which other stains have proven useful in the sytsem under study. It is concluded that automated, rapid-flow photometric identification of blood cell types can produce differential cell counts with good confidence levels.

Blood Cell Count↗