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Biomedical subjects

D A Power

Publications and source records attributed to D A Power.

At least 91 records · Page 5Linked to original sources
PubMed1986

Maternal antibodies to paternal B-lymphocytes in normal and abnormal pregnancy.

Sera were obtained prior to conception and during the first trimester of subsequent pregnancies from 22 women over 27 pregnancies; on 15 occasions these pregnancies ended in spontaneous abortion, whereas the remaining 12 achieved live normal babies. In only one pregnancy ending in abortion could antibodies directed to paternal B-lymphocytes determined by the EA rosette inhibition (EAI) assay be detected in the mother's serum, whereas five of the 12 successful pregnancies were associated with such detectable antibodies. Cytotoxic antibodies were also found in all but one of these EAI-positive pregnancies and no antibody activity was present in sera obtained from five primigravidae. These results indicated that normal, but not abnormal, pregnancies were often associated with blocking antibody formation, suggesting that such antibodies may protect the fetus from abortion. However, the failure to detect antibody activity in sera from first trimester primigravidae argues against a central role for blocking antibody, alone, in the maintenance of outbred pregnancy.

Abortion, Spontaneous↗
PubMed1986

Differential expression of trophoblast lymphocyte cross-reactive (TLX) antigens on T and B lymphocytes.

Heterologous sera raised to human trophoblast (TLX antisera) have been shown to recognize peripheral blood lymphocytes (PBL); in unrelated studies noncytotoxic Fc receptors blocking B lymphocyte antibodies have been found in the sera of women during normal pregnancies. This study aimed to determine whether (a) there was any relation between Fc receptor blocking and cytotoxic anti-TLX activity in ten TLX sera and (b) different reactivity patterns arose when ten TLX antisera were tested in the cytotoxicity assay against separated T and B lymphocytes. Independent factor analysis showed four antisera with T lymphocytotoxicity patterns giving a loading high on one mathematical factor and low on a second. Three sera shared the opposite pattern and three were intermediate. The groups were similar but more discrete than those obtained when PBL were used as targets. Patterns of B lymphocytoxicity were dissimilar from T and both differed from the erythrocyte antibody rosette inhibition activity. Activity did not correlate with the HLA-A, -B, or -DR types carried by the panel cells. These data indicate that TLX antisera contain antibodies directly cytotoxic to antigens differentially expressed on T and B lymphocytes and that noncytotoxic Fc receptor blocking antibodies are not associated with any TLX groupings.

Animals↗
PubMed1986

Identification of HLA-linked antigens by pregnancy-associated non-cytotoxic alloantisera.

Non-cytotoxic sera obtained from post-partum primiparous and multiparous women were examined by a rosette inhibition technique for the presence of antibodies mediating blockade of human B lymphocyte Fc receptors. Selective activity was demonstrated against a panel of normal human B lymphocytes and lymphocytes from patients with chronic lymphocytic leukaemia (CLL). A pattern of specific activity was found in sera and in their IgG fractions, which was not accounted for by antibodies directed to known HLA-A, -B or -DR antigens. Several sera were identified with selective activity in this assay. As the results of testing sera in a direct binding assay correlated with those of the EA inhibition assay, and since EA inhibitory activity occurred in F(ab')2 fractions of sera, it is possible that these non-cytotoxic antibodies bind directly to B cell surface antigens. Sera may therefore have been identified which possess antibodies to hitherto undefined HLA antigens.

Antibodies↗
PubMed1985

Prolonged survival of rat renal allografts after multiple allogeneic pregnancies: strain specificity and role of erythrocyte antibody rosette inhibiting antibodies.

The influence of allogeneic pregnancies on the survival of subsequent rat renal allografts was investigated in three rat strain combinations. Multiple but not single pregnancies produced significantly more long-term surviving kidney grafts than were found in virgin animals; the effect was specific for paternal antigens, as multiple pregnancies by an unrelated strain did not prolong kidney graft survival. In the multiparous groups, those animals with long-surviving grafts had significantly higher levels of non-cytotoxic antibodies against paternal strain B-lymphocytes (detected by the erythrocyte antibody rosette inhibition assay) than did animals which rejected their grafts. The results show that multiple pregnancies may produce a state of specific unresponsiveness to paternal antigens, similar to enhancement, which is marked by the presence of non-cytotoxic antibodies against paternal B-lymphocytes. It is suggested, therefore, that enhancement may be one of the protective mechanisms which prevent rejection of the fetus during pregnancy.

Animals↗
PubMed1985

Evidence that protective Fc-receptor-blocking antibodies in renal transplantation are alloantibodies not autoantibodies.

We have previously shown that the presence in pretransplant recipient sera of Fc receptor blocking antibodies detected by the EA inhibition assay is correlated with improved allograft survival. Twenty-four such sera were assessed for the presence of autoantibodies by the EA inhibition and lymphocytotoxicity assays. No autolymphocytotoxic antibodies were found, and autologous EA inhibition was noted in only one case. EA-inhibiting alloantibodies did occur, and their presence was correlated with improved allograft survival. Sera from 37 dialysis patients were also studied, and neither autologous EA inhibiting nor autologous lymphocytotoxic antibodies were present. Thus Fc receptor blocking alloantibodies that were correlated with improved renal transplant survival were not autoantibodies.

Autoantibodies↗
PubMed1985

IgA nephropathy is not a rare disease in the United Kingdom.

A retrospective analysis of all renal biopsies performed in the Grampian Region of Scotland during 1977-1980 revealed that IgA nephropathy was the most frequently encountered glomerular lesion. The commonest indications for renal biopsy were the presence of asymptomatic urinary abnormalities (90/184; 48.9%) especially asymptomatic haematuria (42/184; 22.8%). A histological diagnosis was made in 36 of the 42 patients presenting with asymptomatic haematuria (85.7%); 16 of the 26 cases of IgA nephropathy presented in this way. Overall, IgA nephropathy was detected in 14.1% of all biopsies and accounted for 21.8% of primary glomerular diseases. This study indicates that IgA nephropathy is apparently more common in Grampian than elsewhere in the United Kingdom. However, it is suggested that this does not represent a true variation in the prevalence of the condition; IgA nephropathy is probably a common cause of haematuria in the United Kingdom.

Adolescent↗
PubMed1985

Acute renal failure: the tip of the iceberg?

This study reports the experience, during a six-year period, of the Aberdeen Renal Unit in the treatment of patients with acute renal failure. The combination of a relatively stable population base and a single regional dialysis centre has allowed the incidence of acute renal failure to be assessed. Approximately 30 patients per million population were dialysed annually for acute renal failure; 69 per cent of these patients (20.5 per million population per year) were dialysed for acute reversible intrinsic renal failure (ARIRF) and mortality in this group was 44 per cent. Patients with more severe disease at the time of presentation to the renal unit, as defined by a clinical severity score, had significantly reduced survival rates. However, it was not possible to predict the outcome in individual cases; ten of 24 patients with clinical severity scores which indicated a poor prognosis survived the period of oliguria and were discharged from hospital. The fact that other renal units dialyse fewer patients per million population per year for ARIRF probably reflects a reluctance to refer patients whose general condition appears poor. As the overall mortality rate reported in this study does not differ significantly from rates reported previously from centres treating a smaller proportion of patients, such decisions may not be correct. It is well known that facilities in Britain for treating patients with end-stage renal disease are inadequate; it now appears likely that some patients who might benefit from acute dialysis are being denied treatment for a potentially reversible disease process.

Acute Kidney Injury↗
PubMed1984

Non-cytotoxic alloantibodies defined by the EA rosette inhibition assay.

Sera from both transfused individuals and pregnant women mediated inhibition of Fc-rosette formation. Both normal blood B lymphocytes and chronic lymphocytic leukemia cells were used as targets. Inhibition was not related to the presence or absence of lymphocytotoxic antibodies. When tested against a panel of B lymphocytes these sera displayed selective reactivity in keeping with the recognition of allospecific determinants. No association between the target antigen(s) and classically defined MHC-coded structures was evident. Heteroantibodies to both class I and class II MHC structures as well as beta 2-microglobulin also mediated FcR blockade. However, unlike the alloantisera tested, these antibodies displayed no restriction in their reactivity toward individual target cells.

Antibodies, Heterophile↗
PubMed1984

The value of autologous indium (111In)-labelled platelets in the diagnosis of renal transplant rejection.

Serial pelvic imaging after injection of autologous platelets labelled with 111In was used to study 22 consecutive patients following cadaver renal transplantation. Increases in isotope uptake by the allografts were observed during episodes of acute rejection (12/22) but not during acute tubular necrosis (4/22). The technique was not influenced by oliguria or hemodialysis therapy. Extra-renal accumulations of labelled platelets were noted in perinephric hematomata and deep vein thromboses.

Acute Kidney Injury↗
PubMed1983

The fetus as an allograft: evidence for protective antibodies to HLA-linked paternal antigens.

Non-cytotoxic antibodies to paternal B lymphocytes were detected in sera from 11 of 11 multiparous women and from 11 of 16 normal primigravidae during the first trimester of pregnancy. These antibodies were not, however, detected in sera from 9 of 10 women of comparable gestation at the time of spontaneous abortion. By means of a rosette inhibition assay, the difference in antibody activity between the primigravidae (mean 37.9 +/- 19%, median 36.5%) and the women subject to spontaneous abortion (mean 7.3 +/- 11.6%, median 0%) was statistically significant. This antibody activity was not directed to the known HLA specificities (HLA--A, B, C, or DR), but linkage to the HLA gene complex was suggested by family studies. These results provide evidence for an HLA-linked antigen system not defined by conventional tissue-typing techniques. Fetomaternal disparity at this antigenic site may be important for successful pregnancy.

Abortion, Habitual↗
PubMed1983

Diagnostic value of urinary N-acetyl-beta-D-glucosaminidase, its isoenzymes and the fractional excretion of sodium following renal transplantation.

Daily total urine N-acetyl-beta-D-glucosaminidase activity, isoenzyme profile and fractional excretion of sodium were measured in 13 consecutive renal transplant patients. Rejection episodes were clinically diagnosed in 12 patients, 11 of whom (92%) showed an increased enzymuria either before or during the onset of clinical signs. The ratio of the two major isoenzymes (A/B) fell during 10 episodes (83%) and in six of these (50%) increased levels of the minor isoenzyme forms were observed. Increased fractional excretion of sodium was associated with nine (75%) of the episodes. Increased fractional excretion of sodium with a raised total enzymuria accompanied by a reduced A/B ratio and an increased proportion of the minor isoenzyme forms occurred in eight (67%) of the rejection episodes. The use of these measurements in the diagnosis of episodes of acute rejection in renal transplantation is discussed.

Acetylglucosaminidase↗
PubMed1983

Identification of subpopulations of T lymphocytes and Ia positive B lymphocytes using a rosette assay based upon the biotin-avidin interaction.

Bovine erythrocytes were coated with avidin using a chromic chloride coupling technique and used successfully in an indirect rosette assay to identify and quantitate: (a) T-lymphocyte helper and suppressor subpopulations, and (b) Ia positive B-lymphocyte populations. Using mouse monoclonal antibodies to the T-lymphocyte markers OKT3, OKT4, and OKT8 it was shown that the proportion of OKT4 and OKT8 positive cells were respectively 60.9 and 39.2% of the total OKT-3 positive T lymphocytes. In a similar way, using a monoclonal anti-human Ia antibody, the percentage Ia positive cells in B-lymphocyte enriched preparations was shown to vary between 18 and 55% for normal peripheral blood and 31 and 58% for chronic lymphocytic leukaemia derived peripheral blood.

Animals↗
PubMed1983

Pretransplant antibodies and renal allograft survival.

Fc receptor blocking antibodies directed against autologous lymphocytes were present in pretransplant sera from only one of a group of 24 cadaver donor renal transplant recipients. Such antibodies were present in recipient sera against B lymphocytes from the donor in 11/24, against normal B lymphocytes in 12/24 and against leukaemic B lymphocytes in 15/24 cases. There was a significant correlation between EA inhibiting antibodies directed against donor (p less than 0.01), normal (p less than 0.05) and leukaemic B lymphocytes (p less than 0.001) and improved one year allograft survival. No autolymphocytotoxic antibodies were detected. Fc receptor blocking antibodies detected by the Erythrocyte Antibody Inhibition assay may thus have a beneficial effect on graft outcome but do not appear to be autoantibodies.

Antilymphocyte Serum↗