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Biomedical subjects

S J Thorpe

Publications and source records attributed to S J Thorpe.

At least 55 records · Page 3Linked to original sources
PubMed1997

International collaborative study to evaluate a recombinant L ferritin preparation as an International Standard.

A recombinant L ferritin preparation, lyophilized in ampoules and designated 94/572, was evaluated by 18 laboratories in 9 countries for its suitability as an International Standard (IS). The preparation was assayed in a wide range of in-house and commercial immunoassays against the 2nd IS for ferritin (of spleen origin; 80/578). The immunological reactivity of the recombinant material was similar to that of the 2nd IS for ferritin in the majority of assays and demonstrated adequate stability in accelerated degradation studies. On the basis of the results presented here, the WHO Expert Committee on Biological Standardization established 94/572 as the 3rd IS for ferritin, recombinant.

Automation↗
PubMed1996

A case of postoperative anxiety due to low dose droperidol used with patient-controlled analgesia.

A multiparous woman in good psychological health underwent urgent caesarean section in labour. Postoperatively, she was given a patient-controlled analgesia device delivering boluses of diamorphine 0.5 mg and droperidol 0.025 mg. Whilst using the device she gradually became anxious, the feeling worsening after each bolus. The diagnosis of droperidol-induced psychological disturbance was not made straight away although on subsequent close questioning the patient gave a very clear history. After she had received a total of only 0.9 mg droperidol, a syringe containing diamorphine only was substituted and her unease resolved completely. We feel that, although the dramatic extrapyramidal side effects of dopaminergic antiemetics are well known, more subtle manifestations may easily be overlooked.

Journal Article↗
PubMed1995

Phobic beliefs: do cognitive factors play a role in specific phobias?

It has long been assumed that specific phobias are by definition, non-cognitive and irrational. However, current cognitive theory suggests that idiosyncratic cognitions may be primary to the experience of phobic anxiety. In this study, conscious beliefs related to exposure to phobic stimuli were assessed. It was found that the majority of specific phobics reported high levels of belief in at least one of a set of cognitions, such as "I would go mad". Analysis of the relationship between phobic anxiety, avoidance, interference and harm cognitions suggests a major role in phobias for harm cognitions as opposed to the other variables. These results appear to indicate that it is difficult to justify the assumption that the nature of specific phobias is essentially non-cognitive.

Adolescent↗
PubMed1995

Development and evaluation of a competitive radioimmunoassay using monoclonal antibodies against Rh D for determining anti-D potency of clinical grade immunoglobulin preparations.

A competitive radioimmunoassay using monoclonal anti-D antibodies has been developed for measuring anti-D activity in prophylactic immunoglobulin preparations. The assay is totally specific for anti-D, reproducible and gives potency estimates comparable to those determined using autoanalyzer methodology. The assay also provides a means for comparing different batches of monoclonal anti-D preparations for red-cell binding activity.

Antibodies, Monoclonal↗
PubMed1994

Immunochemical estimation of haemoglobin types in red blood cells by FACS analysis.

A fixation and permeabilization procedure using formaldehyde and acetone has been developed which allows immunostaining of intracellular haemoglobin for fluorescence activated cell sorter (FACS) analysis of erythrocytes. The treatment preserves antigenicity and light-scattering properties. Validation of the method was given by the correlation of F cell number in adults determined by FACS analysis with that assessed by microscopic examination of cell smears, and by the direct relationship between beta chain synthesis and intensity of beta chain/Hb A immunofluorescence within fetal erythrocyte samples known to vary in their beta chain/Hb A content. The procedure is rapid, non-subjective and sensitive, and makes analysis of haemoglobin content, type and distribution amongst red cell populations possible.

Acetone↗
PubMed1994

Human monoclonal rheumatoid factors: incidence of cross-reactions with tissue components and correlation with VH gene usage.

Human monoclonal antibodies with rheumatoid factor (RF) activity, derived from lymphocytes from the synovial tissue of rheumatoid arthritis (RA) patients and the peripheral blood of healthy individuals were examined for cross-reactivity with tissue and cellular antigens. The majority of IgM RF from RA patients (68%) showed reactivity with at least one component, and were frequently multispecific. A very significantly smaller proportion (28%) of the RF derived from healthy individuals demonstrated reactivities against tissue/cellular antigens (P = 0.004). RF from RA patients most commonly reacted with gastric glands (61%), nuclei (50%) and smooth muscle (50%), whereas RF from healthy donors most commonly reacted with gastric glands (20%), smooth muscle (16%), endothelium (16%) and glomeruli (16%). The most striking difference between the two groups was the reactivity with nuclear components, demonstrated by 50% of the RA RF, but by none of the healthy donor RF. As the two groups of antibodies share the same specificity for IgG Fc, but show differences in variable region segment usage, we investigated the relationship between VH gene usage and tissue/cell cross-reactivity using these antibodies and anti-blood group antibodies. Antibodies using VH3 or VH4 gene segments showed a very significantly greater frequency of tissue/cell reactions than those using VH1 (P = 0.0095 and 0.0004 respectively).

Antibodies, Monoclonal↗
PubMed1993

Human antibody fragments specific for human blood group antigens from a phage display library.

We have isolated human antibody fragments with binding specificities against the blood group antigens of the ABO and I blood group systems (B and HI), of the Rh system (D and E) and of the Kell system (Kpb), by selecting a phage-antibody library on human red cells. The fragments, expressed in bacteria, were antigen-specific and effective in assays including agglutination and immunohistochemistry. Selection of phage-antibody libraries using intact cells seems to offer a promising alternative to hybridoma technology for the production of antibodies against cell surface molecules.

ABO Blood-Group System↗
PubMed1993

Demonstration of autoreactivity by a human monoclonal IgG anti-Rh D antibody.

Human IgG monoclonal antibodies (mabs) against the Rh D antigen have considerable potential for the prophylaxis of haemolytic disease of the newborn. We have carried out in vitro testing for cross-reactions with tissue components by screening two such mabs against animal tissues and a wide panel of human organs from nearly 50 individuals, most of whom were of known Rh D phenotype. Cryostat sections were studied by indirect immunohistochemical techniques. One of the mabs showed non-specific, dose-dependent binding to multiple tissue components whereas the other specifically and consistently reacted strongly with animal smooth muscle and human smooth muscle (vascular, in the walls of hollow viscera, in the respiratory tract) from both Rh D-positive and -negative donors. Immunoprecipitation experiments identified the probable smooth muscle antigen as actin or actin-associated. However, on the basis of inhibition experiments, and by direct estimation of the association constant, the affinity of this mab for smooth muscle was lower than that for Rh D. These results demonstrate autoreactivity by an IgG anti-D mab and show differences in the immunochemical characteristics of human anti-D mabs which may be clinically relevant.

Animals↗
PubMed1993

Human monoclonal IgG rheumatoid factors from the synovial tissue of patients with rheumatoid arthritis.

We have established IgG rheumatoid factor (RF)-secreting hybridoma cell lines from the synovial tissues of two patients (TS and SJ) with rheumatoid arthritis (RA) and one (KL) with the polyarticular form of juvenile rheumatoid arthritis (JRA). The IgG RF bind human and rabbit IgG and all except one form intracellular complement-fixing complexes indicative of a self-association process. The possibility of IgG RF for self association and immune complex formation is a feature thought to be important for the inflammatory processes in RA. Of the IgG RF-secreting cell lines established, three clones from patient SJ and one from patient KL are of the IgG1 kappa isotype while five clones from patient TS are of the IgG2 lambda isotype.

Antibody Specificity↗
PubMed1992

Differences in the characteristics of human monoclonal and polyclonal anti-D as revealed by immunochemical investigations: human monoclonal antibodies share specificities with natural antibodies.

To determine the basis of the tissue cross-reactions shown by some human monoclonal anti-Rh D antibodies, we have investigated the tissue reactivities of 48 further human monoclonal antibodies (mAb) against D and other Rh antigens, and compared them with those of normal and anti-D sera and immunoglobulin preparations, and affinity-purified polyclonal anti-D antibodies. Although we were unable to detect any tissue reactivities associated with the D-binding fraction of polyclonal antisera or prophylactic immunoglobulin, the non-erythroid cell types identified by the tissue-reactive human anti-Rh mAb of both IgM and IgG class were those recognized by antibodies present in both normal and anti-D sera. These results indicate: (a) that the tissue specificities of human anti-Rh mAb are similar to those of natural antibodies, and (b) that there are immunochemical differences between polyclonal and monoclonal anti-D antibodies, at least of IgG class, which may be relevant to the use of the latter in the prevention of haemolytic disease of the new-born by immune prophylaxis.

Animals↗
PubMed1992

Human monoclonal antibodies specific for blood group antigens demonstrate multispecific properties characteristic of natural autoantibodies.

A panel of 72 human monoclonal antibodies with specificities for blood group antigens, A, Rh D, Rh C, Rh c, Rh E, Rh e, Rh G, Jka and Jkb, has been established from the peripheral blood of deliberately immunized donors. Previous work has established that the antibodies are highly specific for their respective blood group antigens, and a number of them are in routine clinical use as blood grouping reagents. This panel was screened for reactivity against six unrelated foreign and autoantigens by ELISA, for rheumatoid factor activity by ELISA and agglutination techniques, and for reactivity with a number of different tissues by immunofluorescence. Binding of the monoclonal antibodies to unrelated exo- and autoantigens was commonly seen amongst the antibodies of the IgM class, and to a lesser degree amongst the IgG class, with reaction patterns similar to those given by natural autoantibodies. Only five of the IgM antibodies failed to demonstrate any unexpected cross-reactivities and these included 1/13 anti-D, 2/7 anti-E, 1/13 anti-c and 1/2 anti-A. We propose that rather than natural autoantibodies representing a distinct population of immunoglobulins, multispecificity (polyspecificity, or polyreactivity) may be a feature of antibodies produced in response to exogenous antigens. The implications of this for the study of autoantibodies are discussed.

Antibodies, Monoclonal↗
PubMed1991

Expression of ABH blood group antigens in human heart tissue and its relevance to cardiac transplantation.

Blood group antigen expression was assessed in cardiac tissue taken during heart transplantation. The samples were from ten donors and nine recipients, of whom seven were blood group A, three were group B, two were group AB, and seven were group O. Cryostat sections were studied by immunofluorescence microscopy. Blood group antigens were confined to the mesothelial cells on the surface of the epicardium and the cardiovascular endothelium where they were consistently demonstrated according to erythrocyte blood group using a rabbit anti-A serum, monoclonal antibodies against A and B antigens, and the H antigen-specific lectin Ulex europaeus. The cardiac muscle itself was negative for blood group antigen. The results indicate that there is some variation in antigen expression between individuals, which may explain why transplants have occasionally been successful in breaching the blood group ABO barrier.

ABO Blood-Group System↗
PubMed1991

Stable lyophilized reagents for the serum ferritin assay.

Two monoclonal antibodies to human ferritin, including one that was coupled to horseradish peroxidase, were lyophilized. These reagents show little loss of activity on reconstitution and demonstrate acceptable stability in the accelerated degradation test. When applied in a simple ELISA for the assay of serum ferritin along with the WHO standard for serum ferritin (80/602) they provide a robust assay with standardized reagents which is potentially suitable for use as a reference assay.

Antibodies, Monoclonal↗
PubMed1991

Detection of blood group A and H-related antigens in normal and neoplastic bladder epithelium: a comparative study using monoclonal antibodies with defined fine specificities.

Three monoclonal anti-blood group H and four monoclonal anti-blood group A antibodies directed at the blood group antigens on Type 1 or Type 2 backbone structures were evaluated as immunohistochemical reagents by indirect immunofluorescence of normal and neoplastic bladder epithelia. The results were compared with fluorescence using polyclonal rabbit anti-A or H sera or Ulex europaeus lectin. The monoclonal antibodies gave less intense or more restricted immunofluorescence than the conventional reagents but showed considerable variation in the extent of their reactivities with urothelial samples from different individuals. In some cases they failed to give immunofluorescence with tissue samples known to contain the immunodominant blood group structures they recognize. In addition, hitherto unsuspected heterogeneity was revealed in the expression of the Type 2-based blood group H and A-structures in the endothelia of neighbouring small blood vessels.

ABO Blood-Group System↗
PubMed1990

Reactivity of a human monoclonal antibody against Rh D with the intermediate filament protein vimentin.

The human IgM anti-Rh D antibody MAD-2 has previously been shown to react with human and animal tissues and leucocytes. Double labelling immunofluorescence with MAD-2 and a mouse monoclonal antibody against vimentin, the intermediate filament protein of cells of mesenchymal origin, showed coincidental staining which was distinct from that seen with antibodies against other cytoskeletal proteins. Using immunoblotting, both MAD-2 and anti-vimentin reacted with a 55 kDa tissue component, and with purified vimentin. These results show that the major tissue and leucocyte protein recognized by MAD-2 is vimentin.

Animals↗
PubMed1990

Developmental patterning of the carbohydrate antigen FC10.2 during early embryogenesis in the chick.

An oligosaccharide antigen (FC10.2), formerly described only in mammalian cells and secreted glycoproteins, has been detected and found to display striking temporal and spatial patterning in the chick during early embryonic development. This antigen is expressed on type 1 chains, which are isomers of oligosaccharides of the poly-N-acetyllactosamine series (type 2 chains). Immunoreactivities before and after neuraminidase treatment of serial sections of chick embryos during the first 17 stages of development indicate that the FC10.2 structure occurs predominantly in the sialylated form (S-FC10.2). The FC10.2 and S-FC10.2 antigens are prominent markers of the primordial germ cells, being strongly expressed by these cells from the pre-primitive streak stage onwards. S-FC10.2 is also a clear marker of the pronephric duct from its first appearance. Initially present over the entire apical surface of the ectoderm, antigenicity diminishes in an antero-posterior direction as neurulation proceeds. A unique pattern for a carbohydrate antigen is displayed by cells of the primitive streak; antigenicity is lost with de-epithelialisation and ingression, but is regained in a pericellular distribution on the mesoderm cells that emerge from the primitive streak. Thereafter, successive changes in expression and distribution of FC10.2 and S-FC10.2 are features of mesodermal tissues, particularly during somitogenesis. These antigens are prominent components of the extracellular matrix around the notochord and sclerotome cells. They are also prominent posteriorly in the subectodermal region, ceasing abruptly at the lateral limits of the embryo proper. Although no absolute correlations can yet be made, several features of the distribution of these antigens suggest that they may be integral components of, or ligands for, cell adhesion molecules.

Animals↗
PubMed1989

Detection of Rh D-associated epitopes in human and animal tissues using human monoclonal anti-D antibodies.

The distribution of Rh D-associated epitopes in human and animal tissues has been assessed by immunochemical techniques using six human monoclonal anti-D antibodies. The IgM antibody MAD-2 reacted predominantly with endothelial cells lining blood vessels and with animal leucocytes and human leucocytes from both Rh D-positive and Rh D-negative donors. Immunoblotting revealed reactivity with a 55 kDa tissue component which was most prominent in homogenates of heart, lung and spleen. In contrast, the IgG antibodies UCHD4 and FOG-1 stained smooth muscle, and UCHD4 in addition weakly stained cardiac and skeletal muscle and the glomeruli of kidney. Immunoblotting with UCHD4 revealed reactivity with a 27 kDa tissue component which was most prominent in heart homogenates. The results show that the six monoclonal anti-D antibodies recognize at least four different epitopes and that Rh D-associated epitopes may occur in non-erythroid cell types.

Animals↗