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Biomedical subjects

J F Kennedy

Publications and source records attributed to J F Kennedy.

At least 73 records · Page 4Linked to original sources
PubMed1982

The use of cellulose carbonate-based immunoadsorbents in the isolation of minor allotypic components of rabbit immunoglobulin populations.

Cellulose trans-2,3-carbonate has been used as a new insoluble matrix for the simple coupling of a1- and b4-positive rabbit immunoglobulin to make immunoadsorbents capable of purifying from serum, with great efficiency, alloantibodies to these allotypic determinants. The antibodies have themselves been conjugated to prepare specific antibody immunoadsorbents of high binding activity for their allotypic target molecules. With these anti-allotypic solid-phase reagents it has been possible to affinity purify a1- and b4-positive immunoglobulin molecules and to deplete serum immunoglobulin of these molecules to leave in the eluates only the allotypically uncontaminated minor immunoglobulin components which are a-negative or b-negative (lambda chain-bearing) molecules. lambda chain molecules were also purified in very small quantities by affinity chromatography on a sheep anti-rabbit lambda chain column. This method of purifying minor populations of rabbit immunoglobulin from normal serum by special immunoadsorbent applications offers new opportunities to study the products of rarely expressed immunoglobulin genes in normal rabbits.

Animals↗
PubMed1981

Use of F(ab')2 antibody fragments in the synthesis of immunoadsorbents for preparing monospecific antigen.

Class specific F(ab')2 antibody fragments were prepared by pepsin digestion of the labile Fc immunoglobulin fragments in antigen--antibody precipitates. The F(ab')2 fragments were covalently coupled to cyanogen bromide-activated Sepharose 4B and the resultant immunoadsorbent used to isolate IgG from human serum with a single chromatographic step, in high yield and purity and negligible non-specific interaction. This technique affords a simple method for preparing an enriched source of class specific affinity-purified immunoglobulin antibodies suitable for many immunochemical applications.

Antibody Specificity↗
PubMed1980

Immobilization of glucoamylase on gelatin by transition-metal chelation.

The potential applicability of glutaraldehyde-crosslinked-gelatin particles for the immobilization of enzymes by encapsulation has been extended by addition of surface-bound enzyme, leading ultimately to a method for the preparation of dual immobilized enzyme conjugates. Attachment of enzyme to the surface of the capsules was achieved by a transition-metal chelation process in which the incoming enzyme becomes a ligand. Glucoamylase was so immobilized, using titanium-urea, -acrylamide, -citric acid, and -lactose complexes or titanium (IV) chloride as means of introducing the titanium chelating centre. The retentions of enzyme activity for both the surface-bound and pre-encapsulated enzymes were functions of the chelating complex chosen. Differences were observed between the action patterns of the two forms of immobilized enzyme. These action patterns and the production of reversion products are discussed in the light of application of gelatin-immobilized glucoamylase to the production of high-DE glucose syrups.

Chelating Agents↗
PubMed1979

Development of gel filtration and specific analyses of urinary carbohydrate and protein material.

Hitherto investigations into urinary carbohydrate and proteinaceous macromolecular material has largely been restricted to non-dialysable fractions. We found that this limits the investigation to less than 1% of the total material present and we present a method for direct analysis of urine without prior concentration or extraction. This method extends existing techniques allowing deeper investigation into necessary and important chemical aspects of health and disease. The method is based on gel filtration using Bio-Gel P2. Means included to overcome the observed adsorption by the gel matrix of relevant material depend on use of high ionic concentration buffers for column elution. The problems of bacterial contamination of the gel matrix are discussed and the use of presterilised urine samples is proposed to prevent contamination. The coupling of the gel filtration column to three specific automated analyses allows simultaneous determination of uronic acid, neutral sugar and proteinaceous material.

Autoanalysis↗
PubMed1977

Active water-insoluble derivatives of papain and other enzymes based on preformed diazonium-type supports.

Papain (EC 3.4.22.2) has been coupled to supports of titanium (IV) oxide and cellulose, which are particulate and pre-coated with diazotised 1,3-diaminobenzene, giving water-insoluble and stable derivatives which possess low proteolytic activity but high esterolytic activity. In addition the reversible binding of zinc (II) at the active site of papain has been exploited to inhibit protectively the enzyme during its linkage to the aforementioned supports, thereby yielding water-insoluble derivatives of papain having superior activity upon reactivation with EDTA. Application of the improved procedure of enzyme coupling to macroporous cellulose particles gave a water-insoluble derivative of papain having further enhanced proteolytic activity. Other properties of the water-insoluble derivatives of papain and of similarly prepared water-insoluble conjugates of urease (EC 3.5.1.5) and cholinesterase (EC 3.1.1.8) with cellulose are also reported.

Cellulose↗
PubMed1977

The fully automatic ion-exchange and gel-permeation chromatography of neutral monosaccharides and oligosaccharides with a Jeolco JLc-6AH analyser.

Experiences with a Jeolco JLC-6AH carbohydrate analyser used to provide a fully automated analysis service for neutral mono- and oligo-saccharides have been summarised. Modifications have been made to the equipment to extend its application, and a method for routine separations of oligosaccharides (d.p. 2--15) has been established. The degree of separation achieved is far superior to that which may be obtained by gel-filtration techniques under gravity- or peristaltic-pump-aided flow. The versatility and adaptability of equipment for use with assays other than the standard orcinol-sulphuric acid reaction shows that it is not too inconvenient to interchange between various assays and separations.

Autoanalysis↗
PubMed1977

Structural identification of isomeric O-trimethylsilyl derivatives of some hexuronic acids.

The structures of the isomeric products obtained on trimethylsilylation of naturally occurring hexuronic acids and their sodium salts and lactones have been established by the application of n.m.r. (for anomeric configuration) and mass spectrometry (for ring size). The equilibria of some of the hexuronic acids in methyl sulphoxide involved a larger proportion of furanoid forms than those in water or pyridine. The proportion of furanoses was also increased by the addition of hexamethyldisilazane. Kinetic evidence indicated that two molecules of each hexuronic acid interacted autocatalytically during mutarotation.

Hexuronic Acids↗
PubMed1977

The use of titanium (IV) oxide for the immobilisation of carbohydrate-directed enzymes.

The use of particles of porous titanium (IV) oxide as a suitable matrix for enzyme immobilisation has been investigated with dextranase. Treatment of the particles with enzyme in the presence and absence of ammonium ions showed that the presence of ammonia induced a greater coupling of protein, whereas a greater retention of enzyme specific activity was achieved in the absence of ammonia. Properties of the immobilised enzyme include a pH-dependence and reversibility of the coupling between enzyme and matrix. The immobilised dextranase was most stable at pH 5.0. Automated analytical techniques for measuring the activity of dextranase and other polysaccharidases in soluble and insoluble forms are also reported.

Ammonia↗
PubMed1977

Ovarian dysgenesis and chromosome abnormalities.

The association of ovarian hypoplasia with trisomy 18 in 6 infants and trisomy 13 in 5 infants and 1 fetus is reported. Three infants also had thymic hypoplasia. The possible etiology of ovarian dysgenesis is discussed in relation to a variety of clinical and experimental associations.

Abnormalities, Multiple↗
PubMed1976

The structures of the carbohydrate moieties of the alpha subunit of human chorionic gonadotrophin.

The alpha subunit of human chorionic gonadotrophin was reduced with dithiothreitol followed by carboxymethylation with iodoacetic acid. The modified glycoprotein was hydrolysed with trypsin to give various peptides, the identities of which were established, and glycopeptides. The glycopeptides were separated by gel filtration and ion-exchange chromatography; they were subjected to component analysis and were found to represent the two carbohydrate moieties in the parent glycoprotein. Sequential removal with glycoside hydrolases of monosaccharide units from the glycopeptides demonstrated (1) that galactose, mannose, glucosamine (2-amino-2-deoxyglucose) and neuraminic acid (5-amino-3,5-dideoxy-glycero-galacto-2-nonulosonic acid) residues possess the D configurations, (2) that the glucosamine units are N-acetylated and (3) the order of the monosaccharide units in the chain, the neuraminic acid units being furthest from the peptide backbone of the subunit and substituting the D-galactose units. Methylation analysis of the glycopeptides by adaptation of the Hakomori technique demonstrated that: (4) D-galactose, D-mannose and N-acetylglucosamine (2-acetamido-2-deoxy-D-glucose) units exist in the pyranose forms; (5) the D-galactopyranose units are linked in the 1 and 6 positions; (6) the D-mannopyranose units exist in several forms, one in a terminal non-reducing position, one as 1,2-linked residues and some as 1,6-linked branch points; (7) the N-acetylglucosamine units are 1,6-linked. On the basis of the results of methylation and enzymic analysis, structures are proposed for the carbohydrate moieties and the assignments are compared with other data previously obtained by periodate-oxidation studies [Kennedy et al. (1974) Carbohydr. Res. 36, 369-377].

Amino Acids↗
PubMed1976

G.L.C. of the O-trimethylsilyl derivatives of hexuronic acids.

The free acids, sodium salts, and lactones of several hexuronic acids have been studied as their O-trimethylsilyl derivatives by gas-liquid chromatography using SE-30 and XE-60 liquid phases. Silylation was best performed in methyl sulphoxide. The equilibrium between the various forms of a hexuronic acid in methyl sulphoxide was also studied by g.l.c. following silylation. The hexamethyldisilazane used in the silylation disturbed the equilibrium attained in the solvent, but this was overcome by premixing the hexamethyldisilazane with chlorotrimethylsilane. Methyl sulphoxide and the silylating reagents gave a two-phase system in which the derivative was favourably partitioned into the upper layer. Partition coefficients and stabilities of the derivatives were measured, and a g.l.c. method for the analysis of the hexuronic acids was thereby developed. The oximes of the hexuronic acids were studied as alternative derivatives for g.l.c., and their equilibrium compositions and g.l.c. retention times are recorded.

Chromatography, Gas↗
PubMed1976

Magnetic, immobilised derivatives of enzymes.

A novel, water, insoluble, stable coating has been attached to various metals, which is capable of covalent attachment to enzymes. The coating (aminobenzoic acid-formaldehyde resin) can be attached to nickel, cobalt, tin, iron, and aluminium. beta-D-Glucosidase has been attached to the coated metals by diazotisation of the coating. The stability and usefulness of the resulting, metallic enzyme-preparations is discussed with special emphasis on the value of ferromagnetic supports for enzymes.

Amines↗