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Biomedical subjects

K Gray

Publications and source records attributed to K Gray.

87 records · Page 5Linked to original sources
PubMed1975

Formation of auto-rosettes by peripheral blood lymphocytes.

A mean of 3-4% (0-5-19-5%) of the peripheral blood lymphocytes of normal adults were shown to bind three or more autologous erythrocytes in vitro to form auto-rosettes. Marked individual fluctuations were observed. Increased percentages were observed in patients with cancer, but not in other selected groups, including a group who had undergone thymectomy for myasthenia gravis. Auto-rosette formation was shown to be a property of T cells by the demonstration of (a) simultaneous binding of autologous and sheep erythrocytes, (b) non-inhibition of auto-rosette formation by anti-immunoglobulin, and (c) formation of auto-rosettes by mitogen-stimulated T blasts. Auto rosette formation is a property of high percentages of human thymocytes, and of lymphocytes treated with neuraminidase or stimulated to blast-cell trans-formation by phytomitogens. It is suggested that auto-rosette formation by these cells is related to their relatively low content of cell-coat sialic acid, as compared with untreated T lymphocytes. The possible influence of the cell coat on lymphocyte function is discussed briefly.

Animals↗
PubMed1970

Electrical interference in non-competitive pacemakers.

Patients with 41 implanted non-competitive pacemakers were investigated. A variety of domestic electrical equipment, a motor-car, and a physiotherapy diathermy apparatus were each operated in turn at various ranges from the patient. Interference effects on pacemaker function were assessed on the electrocardiograph. Medtronic demand 5841 pacemakers were stopped by diathermy while Cordis Ectocor pacemakers developed a fast discharge rate. Cordis triggered pacemakers (both Atricor and Ectocor) were sensitive to interference from many items of domestic equipment and the motor car. The Elema EM153 ran at an increased rate when an electric razor was running close to the pacemaker. The Devices demand 2980 and the Medtronic demand 5841 were not affected by the domestic equipment tested. The significance of interference effects is discussed in relation to pacemaker design.

Adult↗
PubMedDate not supplied

The influence of grid size on accuracy in radiotherapy dose plotting.

The recent article by Niemierko and Goitein [Med. Phys. 16, 239-247 (1989)] illustrates well the errors which are occurring in plotting isodose lines. We wish to augment their analysis with similar work done at Cardiff a few years ago; to indicate some practical treatment outcomes they have omitted; to propose even more stringent requirements of the grid size used; and thus to further alert users and software manufacturers to this problem.

Humans↗
PubMedDate not supplied

Cloning, expression, and functional characterization of two mutant (NAT2(191) and NAT2(341/803)) and wild-type human polymorphic N-acetyltransferase (NAT2) alleles.

The N-acetylation polymorphism segregates individuals into rapid, intermediate, and slow acetylator phenotypes via monogenic inheritance at the NAT2 locus. In a previous study (Arch. Toxicol. 67, 445-452, 1993), we uncovered discrepancies between apparent NAT2 acetylator genotype based on polymerase chain reaction-restriction fragment length polymorphism analysis, in vitro colon arylamine N-acetyltransferase activity, and expected frequency of slow acetylator phenotype in African-Americans, which suggested the presence of not yet defined mutant NAT2 alleles. Two novel NAT2 alleles were discovered after cloning and sequencing of NAT2 polymerase chain reaction products. One allele (NAT2(191)) contained a point mutation at nucleotide 191 [G-->A (Arg-->Gln)], whereas the other allele (NAT2(341/803)) contained two point mutations [341T-->C (Ile-->Thr); 803A-->G (Lys-->Arg)]. The two mutant NAT2 and the NAT2wt alleles were expressed in a prokaryotic expression system. Both the NAT2(191) and NAT2(341/803) mutant alleles expressed functional N-acetyltransferases capable of catalyzing both arylamine N-acetylation and the metabolic activation (via O-acetylation) of N-hydroxy-2-aminofluorene. However, the NAT2(191) and NAT2(341/803) each exhibited significantly lower N- and O-acetylation capacity and were intrinsically less stable than NAT2wt.

Acetylation↗