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Biomedical subjects

P D Mason

Publications and source records attributed to P D Mason.

29 records · Page 2Linked to original sources
PubMed1990

HLA class I expression on erythrocytes and platelets from patients with systemic lupus erythematosus, rheumatoid arthritis and from normal subjects.

It has previously been shown, by a haemagglutination assay, that patients with systemic lupus erythematosus (SLE) express increased levels of HLA class I on erythrocytes compared with normal subjects and patients with rheumatoid arthritis (RA). A radioligand-binding assay, using monoclonal antibody W6/32, was devised to quantify HLA class I expression on erythrocytes and platelets. An increased number of class I molecules was expressed on erythrocytes from 45 patients with SLE (mean = 354 molecules per cell, median = 255 molecules, range = 30-1270 molecules per cell), compared with cells from 46 normal subjects (mean = 132, median = 78, range = 40-550) and 31 RA patients (mean = 132, median = 89, range = 26-497). The presence of HLA-B7 correlated with increased class I expression on erythrocytes from both normal subjects and patients with SLE. Levels of HLA class I in serum were measured. All subjects with HLA-A9 (A23, 24) showed higher levels of serum class I than their A9-negative counterparts, and there was no difference in levels between SLE patients and normal subjects. There were no correlations between class I levels in serum and on erythrocytes amongst SLE patients or normal subjects. Red cells were fractionated, according to their age in vivo, on Percoll gradients. Class I levels fell with increasing erythrocyte age in all individuals, but were higher in all fractions from SLE patients compared with age-matched fractions from normal subjects. HLA-B7-positive erythrocytes also expressed higher class I levels in each Percoll fraction, compared with their HLA-B7-negative counterparts, suggesting that enhanced B7 expression is not due to greater structural stability of this class I allotype. These data are compatible with the hypothesis that class I is expressed as an intrinsic protein of erythrocyte membranes and that expression is increased amongst patients with SLE.

Arthritis, Rheumatoid↗
PubMed1988

Human cytomegalovirus-specific cytotoxic T cells: their precursor frequency and stage specificity.

Human virus-specific cytotoxic T (Tc) cells may be important in maintaining the virus/host equilibrium during persistent herpes virus infections such as that with human cytomegalovirus (HCMV). We have previously shown that HCMV-specific Tc cells are present in peripheral blood in normal asymptomatic seropositive individuals (L. K. Borysiewicz et al., Eur. J. Immunol. 1983. 13: 804). In this study we have used limiting dilution analysis to estimate the precursor frequency of these Tc cells and to further delineate their specificity for viral proteins expressed at different stages of the virus replicative cycle. HCMV-specific Tc precursor cells were present in peripheral blood lymphocytes (PBL) at a frequency of 1/5000 to 20,000 E+ PBL. This frequency was higher than that observed for varicella-zoster virus (VZV)-specific Tc cells (1/30,000 to greater than 500,000) in asymptomatic individuals and was similar to the VZV Tc precursor cell frequencies observed following clinical reactivation (1/30,000). When the stage specificity of clonally derived HCMV-specific Tc cells was analyzed, using target cells treated with phosphonoformate to allow expression of only the nonstructural viral proteins, the majority (60%) of Tc cells lysed these cells. A number of Tc cells lysed only cells which expressed the structural or late HCMV proteins. These results suggest a high precursor frequency of HCMV-specific Tc cells in PBL, and that there are subpopulations of such Tc cells specific for HCMV antigens expressed at different stages of the virus replicative cycle. However, the relative frequencies of these subpopulations suggest that the immunodominant HCMV antigens with respect to the Tc response are expressed at immediate early and/or early times.

Cells, Cultured↗
PubMed1988

Suppressive role of NK cells in pokeweed mitogen-induced immunoglobulin synthesis: effect of depletion/enrichment of Leu 11b+ cells.

Natural killer (NK) cells probably have immunoregulatory effects. However, the evidence to date is mainly based on the suppressive effect of enrichment with relatively impure NK populations (large granular lymphocytes, LGL, Leu 7a+ cells). Here we report on the effect of enrichment and depletion of Leu 7a+ and Leu 11b+ cells (the latter containing virtually all NK activity in freshly prepared lymphocytes) on pokeweed mitogen (PWM)-induced immunoglobulin (Ig) synthesis. Enrichment suppressed Ig synthesis to a degree dependent on the number of cells added, and was not enhanced further by their pretreatment with interferon. Furthermore, depletion of Leu 11b+ cells from peripheral blood lymphocytes (PBL) led to marked enhancement (2-25-fold increase) of Ig synthesis, suggesting these cells may normally exert a suppressive effect. The possible underlying mechanisms were investigated further. Enhanced Ig synthesis by Leu 11b-depleted cultures was associated with an increased number of Ig-secreting cells by plaque assay, but with no change in numbers of CD4+ or CD8+ cells. Treatment of PBL with monoclonal antibodies (anti-Leu 7a/Leu 11b) alone suppressed PWM-induced immunoglobulin synthesis. We conclude that NK cells play a role in the regulation of Ig production, at least in part by an effect on activation/differentiation of B cells, but independent of altered T-cell subpopulations. The effect may be unrelated to their cytotoxic function (being unaffected by interferon, IFN), although the direct effects of anti-Leu 11b and Leu 7a in enhancing the suppressive effect suggest an alternative activation pathway.

Antibodies, Monoclonal↗
PubMed1987

Experience with nalbuphine, a new opioid analgesic, in acute myocardial infarction.

A total of 141 patients admitted to hospital with a diagnosis of suspected myocardial infarction were randomized to treatment with intravenous diamorphine (71) or nalbuphine (70). Myocardial infarction was subsequently confirmed in 109 patients. Both drugs provided good analgesia. Heart rate, blood pressure, respiratory rate, peak flow and minute volume were measured over a three-hour study period. Except for a slight fall in systolic blood pressure in the nalbuphine-treated group, there were no statistically significant differences between the groups. The nalbuphine-treated group had higher levels of aspartate aminotransferase and hydroxybutyric acid dehydrogenase but not creatine phosphokinase. The haemodynamic outcome and mortality at three months of the two groups were similar. It is concluded that nalbuphine provides effective analgesia coupled with few adverse circulatory or respiratory effects.

Analgesics↗
PubMed1986

Rapidly progressive nephritis in patients taking hydralazine.

Two patients with rapidly progressive glomerulonephritis associated with hydralazine are reported. The different types of hydralazine toxicity recognized are "lupus" syndrome, vasculitis and most recently proliferative nephritis with renal failure. These are reviewed with some discussion of possible mechanisms.

Female↗
PubMed1985

SBE presenting with type III cryoglobulinaemia.

A case of subacute bacterial endocarditis which presented with cryoglobulinaemia is reported. A secondary cause of cryoglobulinaemia was suggested following characterization, which revealed a Type III (mixed polyclonal) cryoprotein. Levels of cryoglobulin were high and remained so until the source of infection was eradicated, and the cause of the cryoglobulinaemia is briefly discussed.

Complement System Proteins↗