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Biomedical subjects

G R Bushell

Publications and source records attributed to G R Bushell.

At least 19 recordsLinked to original sources
PubMed1992

Vaccination of cattle with dextran sulphate-binding Babesia bigemina antigens.

Dextran sulphate-bound Babesia bigemina antigens were used in a preliminary vaccination study and were shown to elicit a protective immune response in cattle. A dextran sulphate-binding fraction of B. bigemina was further subfractionated on a Phenyl Sepharose column to give two fractions--one that strongly bound to the column (bound fraction) and one that did not (unbound fraction). Two groups of cattle were each vaccinated with either the bound or the unbound fraction. These two groups of animals along with a control group were then challenged with B. bigemina-infected erythrocytes. Both groups of vaccinated animals showed considerably lower mean daily parasitaemias as compared to the control group.

Animals↗
PubMed1991

Babesia bovis host cell recognition proteins.

Babesia bovis enters host erythrocytes by invagination but nothing is known of the proteins involved. By means of metabolic labelling, differential centrifugation in oil and salt elution, a number of babesial proteins have been shown to bind to bovine erythrocytes. Strong binding is evidenced only by a 38/19 kDa pair. Preliminary experiments indicate that these two proteins also bind to human erythrocytes, although apparently to a lesser extent.

Animals↗
PubMed1990

The effect of Plasmodium falciparum exo-antigens on the morphology of uninfected erythrocytes.

It was observed that uninfected red cells resuspended in supernatant from Plasmodium falciparum cultures, then examined between a glass slide and cover-slip, assumed varying morphologies. A series of experiments suggested that P. falciparum releases molecules which cause red cells to become stomatocytic (cupped). These molecules, some of which are heat-stable have an apparent molecular weight greater than 12 kDa, are released at or about schizogony, and do not bind tightly to erythrocytes.

Animals↗
PubMed1988

Localisation of internal antigens of Plasmodium falciparum using monoclonal antibodies and colloidal gold.

By the examination of several defined malarial antigens, we have demonstrated the necessity for etching pretreatments to be used in conjunction with post-embedding immunolabelling of LR White-embedded parasite material. In general, etching procedures markedly enhanced immunolabelling of the various antigens, while in some cases etching was essential for obtaining positive immunolabelling. Of the etching pretreatments evaluated, a combination of an alcoholic solution of sodium hydroxide followed by sodium metaperiodate gave optimal labelling with minimal background. A number of fixation regimes were also compared for their applicability to immunolabelling of malaria-infected erythrocytes. Generally, fixation with low concentrations of glutaraldehyde was found to be appropriate. We have also successfully used paraformaldehyde fixation coupled with etching to localise a rhoptry-associated antigen, which is presumably sensitive to glutaraldehyde fixation. Due to the high specificity of monoclonal antibodies, however, different fixation regimes may need to be considered for various combinations of antigen and antibody.

Acrylic Resins↗
PubMed1988

An antigenic complex in the rhoptries of Plasmodium falciparum.

A previously identified putative rhoptry antigen of Plasmodium falciparum is composed of two major components, one of 80 kDa and a doublet at 42/40 kDa. An inhibitory monoclonal antibody immunoprecipitated both the 80 kDa protein and the 42/40 kDa doublet, but immunoblotted only the 80 kDa component. A second monoclonal antibody, raised against the affinity purified complex, immunoblotted only the 42 kDa band under non-reducing conditions. Electron microscopic examination of thin sections of parasites immunolabeled with these monoclonal antibodies and colloidal gold anti-mouse conjugate has confirmed that this antigen is localised in the rhoptry organelles of mature schizonts and free merozoites. The antigen is associated with apparent membranous structures released from free merozoites. Immunoblotting and immunoprecipitation with two different monoclonal antibodies, and protease digestion experiments, have clearly demonstrated that this antigen is a complex composed of two separate and distinct proteins, and does not represent a monomer/dimer pair. The 80 kDa protein is synthesised as an 84 kDa precursor.

Animals↗
PubMed1988

The 140/130/105 kilodalton protein complex in the rhoptries of Plasmodium falciparum consists of discrete polypeptides.

Four monoclonal antibodies (MAbs) recognise an antigen localised in the rhoptries of Plasmodium falciparum merozoites using both indirect immunofluorescence assay and immunoelectron microscopy with immunogold labeling. All MAbs immunoprecipitated bands at 140, 130 and 105 kDa from [35S]methionine-labeled parasites; however, one MAb immunoblotted only the 130 kDa protein and another MAb immunoblotted the 105 kDa protein. The affinity purified antigen complex consisted of proteins of 140, 130, 105 and 98 kDa. The individual proteins were subjected to peptide mapping with Staphylococcus aureus V8 protease; the 98 kDa protein was a degradation product of the 105 kDa protein and the 140, 130, and 105 kDa proteins were found to be unrelated. The antigen complex was synthesised at the mid trophozoite stage and was considered to be soluble as judged by release from mature schizonts by freeze/thaw lysis. One of the MAbs inhibited parasite growth and/or merozoite invasion of erythrocytes, in vitro, to a small but significant extent.

Animals↗
PubMed1988

An epitope recognised by inhibitory monoclonal antibodies that react with a 51 kilodalton merozoite surface antigen in Plasmodium falciparum.

Monoclonal antibodies designated 8G10/48 and 9E3/48 raised against mature asexual blood stages of Plasmodium falciparum inhibit parasite growth in vitro. Both antibodies bind to an epitope which includes the linear sequence Ser Thr Asn Ser and which is present in a cDNA clone from a P. falciparum expression library. These antibodies recognise a glycosylated antigen of approximately 51 kDa which is located on the merozoite surface membrane.

Amino Acid Sequence↗
PubMed1988

Inhibitory monoclonal antibody against a (myristylated) small-molecular-weight antigen from Plasmodium falciparum associated with the parasitophorous vacuole membrane.

A small-molecular-weight antigen that occurs in asexual blood stages in synchronized cultures of Plasmodium falciparum was detected by a monoclonal antibody which inhibits parasite growth in vitro. This antigen, QF116, showed a molecular weight of 15,000 in parasite strain FCR-3K+ from The Gambia and 19,000 in strain FCQ-27 from Papua New Guinea. The protein did not show significant glycosylation by galactose or glucosamine labeling but was found to be acylated by myristic acid. By using immunogold labeling and electron microscopy, the location of the antigen could be attributed to the parasitophorous vacuole membrane and to inclusions and vesicles residing within the cytoplasm of the erythrocyte host cell.

Animals↗
PubMed1986

A rhoptry antigen of Plasmodium falciparum contains conserved and variable epitopes recognized by inhibitory monoclonal antibodies.

Four monoclonal antibodies produced against Plasmodium falciparum recognize an antigen in merozoites that is localized in rhoptries, as judged by a punctate, double dot fluorescence pattern. All four antibodies bound to the same affinity purified antigen in a two site immunoradiometric assay. Immunoprecipitation of antigen by monoclonal antibody followed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis yielded protein bands of 80, 66 and 42 kDa. Western blotting gave bands of 80 and 66 kDa only with three of the antibodies: the fourth did not blot. Based on protease inhibitor data the 66 kDa band is considered to be a cleavage product of the 80 kDa band, but the 42 kDa band does not appear to derive from the latter and may be a coprecipitation product. This group of antigens labels with both [35S]methionine and [3H]histidine. Two of the monoclonal antibodies inhibited merozoite invasion of erythrocytes. One of these inhibitors recognizes a variable epitope, whereas the second recognizes a highly conserved epitope present in all 106 primary isolates of P. falciparum tested from Brazil, Thailand and Papua New Guinea.

Animals↗
PubMed1979

Neutral protease inhibitors from human intervertebral disc and femoral head articular cartilage.

Assays of several proteases, incorporating guanidinium chloride extracts of human femoral head cartilage and intervertebral disc, demonstrated that both tissues contain inhibitors of certain serine proteases. Trypsin, chymotrypsin and a granule extract of human polymorphonuclear leukocytes containing elastase and cathepsin G activities, were inhibited by low molecular weight fractions prepared by Sephadex G-75 chromatography. Using a radioassay, it was further shown that these fractions inhibit proteolysis of cartilage proteoglycan. The inhibitor in intervertebral disc is concentrated in the nucleus pulposus, with a decreasing gradient to the periphery of the annulus fibrosus. It is proposed that these inhibitors confer at least partial protection against pathological proteolysis of the proteoglycans in human articular cartilage and nucleus pulposus.

Animals↗
PubMedDate not supplied

Collagens, elastin and noncollagenous protein of the intervertebral disk.

This is a review of the recent developments in collagens, elastin, and noncollagenous protein of the normal and abnormal intervertebral disk. Much progress has been made on the chemistry of the normal disk constituents. However, little work has been done to date on the essential lesion of the early degenerative disk in humans; a major effort in this field is indicated in the next decade. The reasons are obvious, for in the unraveling of the etiology of degeneration of the intervertebral disk lies the hope and expectation of prevention of disk failure.

Chemical Phenomena↗
PubMedDate not supplied

Biomechanics and biochemistry of the intervertebral disks: the need for correlation studies.

The literature on the biomechanics of the intervertebral disk is reviewed with emphasis on biomechanical--biochemical--morphological correlative studies. The deficiency of definitive correlative studies is apparent and an appeal is made to interested investigators to fill in the voids in this extremely important area of study. A comprehensive theory of intervertebral disk failure awaits application of existing biomechanical, biochemical and morphological techniques in a detailed and methodical manner to the normal and early degenerative human intervertebral disks.

Animals↗