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Biomedical subjects

D C Kilpatrick

Publications and source records attributed to D C Kilpatrick.

At least 109 records · Page 6Linked to original sources
PubMed1983

Enzymatic modification of the lymphocyte surface. Application to tissue typing and rosetting with sheep erythrocytes.

Lymphocytes were treated with hydrolytic enzymes primarily to assess whether such modified cells would give improved cytotoxicity reactions during tissue typing. Papain-treated and alpha-chymotrypsin-treated lymphocytes were approximately twice as sensitive as untreated cells in the microcytotoxicity test used, and this finding might be usefully exploited by immunological laboratories for purposes of cross-matching, HLA antibody screening and HLA-DR typing. Trypsin treatment promoted massive cell clumping, while neuraminidase treatment was responsible for indiscriminate cell death after exposure to rabbit serum. The capacity of lymphocytes to form rosettes with sheep erythrocytes was abolished after treatment with trypsin or alpha-chymotrypsin, but enhanced by papain or neuraminidase.

Animals↗
PubMed1981

Alkaline phosphatase from human thyroid.

Alkaline phosphatase activity was found in human thyroid homogenate at a specific activity of about 0.01 units/mg protein. The enzyme responsible appears to be a membrane-bound sialoglycoprotein. The properties of thyroid membrane alkaline phosphatase were examined after extraction with non-ionic detergent or butanol. It was detected mainly as a single electrophoretic form with a mobility similar to that of the liver form of the enzyme. It was readily inhibited by homoarginine, but not by phenylalanine. It reacted in Ouchterlony double diffusion with antiserum raised against liver alkaline phosphatase, but not with antiserum to placental alkaline phosphatase. Heat treatment at 56 degree C for 10 min at pH 7.5 resulted in an approx. 50% loss of enzyme activity. Its relative molecular mass was estimated to be 320000 by gel filtration, and 300000 by gradient gel electrophoresis. It required magnesium for full activity, and had a pH optimum of 10.5 in Tris-borate buffers. It was concluded that thyroid alkaline phosphatase belongs to the liver/bone/kidney isoenzyme group, but may exist in a molecular form distinct from others previously described.

Alkaline Phosphatase↗
PubMed1981

Complexes in serum between alkaline phosphatase and immunoglobulin G: immunological and clinical aspects.

A retrospective study was performed on 31 patients in whose sera an immune complex between alkaline phosphatase and immunoglobulin G had been detected. The average age of these patients was 64 years and the sexes were equally represented. Twenty-three patients (74%) had a disease with either an autoimmune aetiology or associated with circulating immune complexes or autoantibodies. Sera from 16 patients were tested for the presence of circulating immune complexes in addition to the alkaline phosphatase immune complex, and these complexes were detected in 14 cases (88%). Sera from 17 patients were tested for the presence of specific autoantibodies and these were detected in 9 cases (53%). Twelve patients were followed up for a mean period of 11.6 months (range 0.5 to 39 month). At the end of the follow-up period, 10 patients (83%) showed persistence of the immunoglobulin-G-alkaline phosphatase complex.

Alkaline Phosphatase↗
PubMed1981

Some studies on the polyethylene glycol turbidity method for detecting immune complexes in serum.

A rapid and simple method for detecting circulating immune complexes based on turbidity measurements following polyethylene glycol precipitation was studied with regard to its suitability as a routine assay in clinical laboratories. This method was found to have an acceptable degree of precision provided the temperature was carefully controlled. The mean value obtained with a group for 70 blood donors was 0.09 (SD 0.05) and the 90th percentile value was 0.16. There was no significant difference between values obtained from groups divided on the basis of age or sex. Of 70 diabetic sera assayed by the polyethylene glycol turbidity method, 20% gave positive values although only 10% were strongly positive. The corresponding figures for the solid phase Clq binding method were 15.7% and 14.3%, respectively. Correlation between the two methods was poor. It was concluded that although both methods have a similar likelihood of detecting immune complexes in randomly selected diabetics, it is probable that different immune complexes were being detected.

Antigen-Antibody Complex↗
PubMed1980

Isolation of a lectin from the pericarp of potato (Solanum tuberosum) fruits.

A lectin has been isolated from potato (Solanum tuberosum) fruits by affinity adsorption on to glutaraldehyde-fixed erythrocytes and elution with oligomers of N-acetylglucosamine. The characteristics of the lectin resemble those of the potato tuber lectin and other closely related lectins from solanaceous plants.

Acetylglucosamine↗
PubMed1980

Purification and some properties of a lectin from the fruit juice of the tomato (Lycopersicon esculentum).

In the tomato (Lycopersicon esculentum) plant, the fruit juice was found to be the richest source of agglutinating activity. The lectin responsible could be inhibited by oligomers of N-acetylglucosamine, and this property was exploited to purify the lectin by affinity adsorption on trypsin-treated erythrocytes. The lectin is a glycoprotein that cross-reacts immunologically with the lectin from Datura stramonium (thorn-apple).

Carbohydrates↗
PubMed1980

Measurement of circulating immune complexes by radioimmunoassay of immunoglobulin in high molecular weight fractions.

A method for detecting circulating immune complexes is described based on radioimmunoassay of IgG following the rapid separation of immune complexes from monomeric IgG on short columns of Sephacryl S-300. Values obtained using sera from patients with immune complex associated diseases were distinctly higher than those obtained with sera from healthy control subjects. The same serum samples were assayed by 3 other methods for detecting immune complexes; significant correlation was obtained.

Animals↗
PubMed1980

The effect of chymotrypsin on the development of Dictyostelium discoideum.

Development of the cellular slime mould Dictyostelium discoideum strain NC4, in the presence of alpha-chymotrypsin (3 mg/ml) is reversibly arrested at the tight aggregate stage (10/12 h). Pronase has a similar effect, but trypsin only retards normal development by about five hours. Normally developing cells are susceptible to alpha-chymotrypsin if they are transferred into its presence at any time up to the tight aggregate stage (10-12 h). Transfer after this stage does not affect the appearance of fruiting body structures in the normal time (24 h). Electron microscopy showed the ultrastructure of alpha-chymotrypsin-blocked aggregates after starvation for 24 h to be consistent with a block at 10-12 h of normal development. Poorly developed prespore vacuoles, having thin incomplete walls and a paucity of electron-dense material, are present in some cells. No angular vacuolated cells characteristic of stalk cells are visible. Fruiting bodies formed in the presence of a alpha-chymotrypsin, either as minority structures when the enzyme is added before 10-12 h of normal development, or as the majority structures on later enzyme addition, were found to be abnormal. Normal stalks were formed but the spores were immature. Prespore vacuoles were present, though disrupted, and the cells were not encapsulated by spore walls. The electronegativity of intact slime mould amoebae was significantly reduced, and material containing L-[6-3H]-fucose and [1-14C]leucine was removed from the cell surface on alpha-chymotrypsin treatment. Few plasma membrane proteins were affected, however, and staining of polyacrylamide gels for glycopeptides using Con A-peroxide binding also showed little change.

Chymotrypsin↗
PubMed1979

Tissue and subcellular distribution of the lectin from Datura stramonium (thorn apple).

Plants of Datura stramonium (thorn-apple) were dissected into their component tissues and examined for the presence of the Datura lectin. This lectin was easily detected in seeds and in various parts of the flowers of adult plants. Traces were also found in green (emerged) cotyledons and roots of seedlings. The specific lectin activity in seeds contained within the fruits increased as the seeds matured. Mature seeds were homogenized in sucrose and separated by differential centrifugation into four fractions, three of which were clearly of distinct composition. Most of the lectin activity sedimented with the low-speed (cell-wall/protein-body) pellet, but a similar specific activity was recovered from the other fractions. However, if EDTA was included in the homogenization medium, three or four times more lectin activity was recovered in the soluble fraction. Immunofluorescent staining of formaldehyde-fixed sections showed that the lectin was localized in the cytoplasm, with little associated with cell walls. The possible relevance of these results to the function of the lectin in plant cells is discussed.

Datura stramonium↗
PubMed1978

Purification of the lectin from Datura stramonium.

The lectin from Datura stramonium can be inhibited by oligomers of N-acetylglucosamine. This property was exploited to purify the lectin by affinity chromatography on Sepharosefetuin. The purified lectin is a glycoprotein in having subunits of 40 000 and 45 000 mol.wt.

Acetylglucosamine↗
PubMed1978

Carbohydrate composition of cells and plasma membranes of Dictyostelium discoideum at selected stages of development.

Cells of Distyostelium discoideum representing four developmental stages were auto-analysed for constituent monosaccharides and their compositions compared. Rhamnose, ribose, fucose, glucose, mannose, galactose, glucosamine, galactosamine and an unidentified sugar were recovered after hydrolysis in 2 M HCl for 2 h at 100 degrees C. The relative proportions of the individual sugars were found to vary as a function of development. The largest variations were in the proportions contributed by galactose (from 2% of vegetative cell carbohydrate to 12% of the carbohydrate of fruiting bodies) and galactosamine (present in measurable quantity only in fruiting bodies). Plasma membrane "ghosts" were found to have the same monosaccharide constituents as whole cells, but in different proportions. Mannose contributed over 24% of the total carbohydrate recovered from aggregating cell "ghosts", but only 13% of carbohydrate recovered from "ghosts" prepared from vegetative cells. Galactose was the most abundant sugar recovered from vegetative "ghosts", and was second only to mannose in aggregating "ghosts".

Amino Sugars↗
PubMed1977

Glycosidases from the culture medium of Physarum polycephalum.

Eight exo-glycosidase activities were detected in the axenic culture medium of the myxomycete, Physarum polycephalum. The secretion of each enzyme examined followed the growth curve and continued during the stationary phase after the cessation of growth. Two or more forms of each enzyme were detected after electrophoretic separation. The beta-N-acetyl-D-hexosaminidase activity was readily separated into its two electrophoretic forms, X and Y, which were purified 145- and 306-fold respectively. These beta-N-acetyl-D-hexosaminidases had several similar characteristics. Evidence is presented that the major electrophoretic form of alpha-D-galactosidase is heterogeneous. The possible functions of extracellular glycosidases in teir occurrence and properties.

Culture Media↗
PubMed1976

Properties and developmental regulation of an alpha-d-galactosidase from Dictyostelium discoideum.

An alpha-D-galactosidase was detected in cells of the cellular slime mould, Dictyostelium discoideum, at all stages of development. Its specific activity was highest during early development (interphase), and this accumulation of enzyme appears to require protein synthesis de novo. Its subcellular distribution differs from that of other D. discoideum glycosidases, since most activity was recovered in the soluble fraction. No evidence was obtained for more than one isoenzymic form after subjection of extracts to electrophoresis and various chromatographic procedures. It is excreted from the cell during development, but no evidence was found for an extracellular function for the enzyme.

Cycloheximide↗