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Biomedical subjects

A H Merry

Publications and source records attributed to A H Merry.

At least 55 records · Page 3Linked to original sources
PubMed1984

Quantitation of antibody binding to erythrocytes in LISS.

The amount of antibody bound to cells in a low ionic strength solution (LISS) has been quantitated for several antibodies including anti-D, anti-c, anti-Kell, anti-Fya, and anti-Jka. With the exception of the Kell antibodies there was an enhancement of the rate of antibody uptake in LISS. For Rh antibodies the amount bound after a 5-min LISS incubation is comparable to that bound after 45 min in saline. For Kell antibodies a smaller amount was bound in LISS than in saline. The effect of the ratio of serum to cells was also studied, and with several antibodies there was an increase in the amount of antibody bound with a higher serum to cell ratio irrespective of suspending medium. For Kell antibodies this ratio appears to be of greater importance than the ionic strength for antibody detection. A modification to the LISS method to increase the serum to cell ratio is, therefore, presented.

Antigen-Antibody Complex↗
PubMed1984

The quantification of erythrocyte antigen sites with monoclonal antibodies.

The application of monoclonal antibodies to the quantification of blood group antigen sites on erythrocytes was examined. A second antibody technique using labelled anti-mouse IgG could not be used as it was not possible to predict the binding ratio between this and the monoclonal antibody. A series of monoclonal antibodies (R10, R18, BRIC 13, BRIC 14) to the erythrocyte sialoglycoprotein alpha (syn: glycophorin A) showed the number of antigen sites to be from 0.3 X 10(6) to 1.2 X 10(6) per erythrocyte and supported the conclusion that the Wrb antigen is located on this protein. An antibody with a specificity related to the Rh blood group system (R6A) showed 4.6 - 10.4 X 10(4) binding sites to be present on cells of phenotype cCDEe. On cells of phenotype -D- 1.24 X 10(4) binding sites were present but protease treatment increased the number of available sites to 1.3 X 10(5). An antibody to a Kell-related antigen (BRIC 18) recognized 2.5 - 5.9 X 10(3) sites per erythrocyte on cells of phenotype Kk. However, a similar number also appeared to be present on cells of the McLeod and Ko phenotypes although the affinity for the antigen on these cells was very much reduced. The potential of using monoclonal antibodies for this purpose and the value of this in the study of blood group systems has been demonstrated.

Animals↗
PubMed1983

Positive direct antiglobulin test in normal individuals. II.

Investigations into the IgG sub-types and number of molecules of IgG present on the red cells of 22 apparently normal healthy blood donors with positive direct antiglobulin tests are described. In all cases, the sub-type was IgG1 or IgG4, and none had more than 1000 mol of IgG per red cell. It is suggested that sequestration of IgG-coated cells only occurs when the number of IgG1 mol per cell reaches a certain level.

Blood Donors↗
PubMed1983

The quantification of C3 fragments on erythrocytes: estimation of C3 fragments on normal cells, acquired haemolytic anaemia cases and correlation with agglutination of sensitized cells.

A sensitive method is described for the quantification of C3 fragments on erythrocytes. A radiolabelled monoclonal antibody, was used which was directed against a C3d determinant on all forms of cell bound C3. The number of C3 molecules on normal erythrocytes was estimated to be 420 +/- 140. The strength of the antiglobulin test increased from negative to 5+ over a range of only 850 C3 molecules (400-1250). A blood donor with a positive direct antiglobulin test was found to have 4800 molecules per cell whereas three cases of cold haemagglutinin disease with active haemolysis had from 16 000 to 52 020 C3 molecules per cell. This test has an application in the testing of acquired haemolytic anaemia cases with a positive direct antiglobulin test with C3 bound to the cells and in the standardization of sensitized cells used for testing antiglobulin reagents by various serological techniques.

Anemia, Hemolytic↗
PubMed1983

Five-day storage of platelet concentrates. II. In-vivo studies.

Following in-vitro tests it was concluded that platelet concentrates stored for 5 days at 22 degrees C in polyolefin containers, coded PL732, should be as effective in clinical practice as similar concentrates stored in the standard PVC containers, coded PL146. These predictions have been confirmed by the following in-vivo tests; autologous survival studies in volunteers, determination of recovery, platelet increment calculations 1 and 24 h after transfusion and clinical appraisal after transfusion of haemorrhagic thrombocytopenic patients. Bacteriological cultures of the platelet concentrates were sterile after storage for more than 5 days. It can be concluded that the 5-day storage of platelet concentrates in these containers is a practical proposition.

Blood↗
PubMed1982

A quantitative antiglobulin test for IgG for use in blood transfusion serology.

A sensitive method has been developed using 125I-labelled anti-IgG which allows detection of IgG present on the red cell surface. By suitable absorption and correction for non-specific binding to trypsinized red cells, a reproducible, accurate method of quantitating IgG absorbed onto red cells is obtained. The number of IgG molecules present on normal cells was found to range from 5 to 90 with an average of 39. Studies of correlation of agglutination in the antiglobulin test with numbers of IgG molecules on the cell were also undertaken.

Blood Transfusion↗
PubMed1981

A rapid purification method for peanut anti-T lectin.

A novel method for the purification of the anti-T lectin from peanuts is described. The method is simple, easy to perform and requires no special reagents. The lectin is obtained in a highly purified from comparable to that prepared by affinity chromatography and large scale preparations are readily made. The lectin was shown by serological tests to have anti-T activity and is suitable for detection of minor T antigen activation on red cells.

Antibody Specificity↗
PubMed1980

Positive direct antiglobulin test in normal individuals.

65 normal, healthy people with a positive direct antiglobulin test (DAT) have been identified in a population of blood donors over a period of 14 years. 32 of them have been recalled for detailed study. A strong positive correlation with increasing age was noted, comparable to that seen in hospital patients with a positive DAT. No feature known to cause a positive DAT was identified in the healthy individuals, only 1 of whom went on to develop autoimmune haemolytic anaemia.

Adolescent↗
PubMed1980

A simple method for th production of anti-C3 antiserum in rabbits.

A method is described for the production of an anti-C3+d specific antiserum in rabbits. The method does not require purification of C3 but relies on the binding of human C3 to the rabbit erythrocytes following activation of the alternative pathway. The antiserum produced is suitable for use as either a serological reagent or for immunoprecipitation.

Animals↗
PubMed1977

The disulphide-bonded nature of procollagen and the role of the extension peptides in the assembly of the molecule.

1. The molecular weights of chick tendon and cartilage procollagens, and their constituent polypeptides, were determined by gel filtration and gel electrophoresis. The values obtained are in good agreement and indicate that the mol.wts. of the secreted procollagens (types I and II) and their individual pro-alpha-chains are of the order of 405 000-445 000 and 137 000-145 000 respectively.2. Digestion of tendon procollagen with human rheumatoid synovial collagenase gave products consistent with the presence of large non-helical peptide extensions at both N-and C-termini. Electrophoretic analysis gave apparent mol.wts. of 17 500 and 36 000 for the respective N- and C-terminal extensions of pro-alpha1(I)-and pro-alpha2-chains, and inter-chain disulphide bonds were restricted to the C-terminal location. 3. During the biosynthesis of procollagen by tendon and cartilage cells a close correlation was observed between the extent of inter-chain disulphide bonding and the proportion of procollagen polypeptides having a triple-helical conformation. These processes appeared to commence in the rough endoplasmic reticulum and be completed in the smooth endoplasmic reticulum, but the rate at which they occur in cartilage cells is markedly slower than that found in tendon cells. 4. When the intracellular [14C]procollagen polypeptides present in the rough-endoplasmic-reticulum fractions of tendon and cartilage cells were analysed under non-reducing conditions on agarose/polyacrylamide composite gels, no significant pools of dimeric intermediates were detected. 5. In both cell types, inter-chain disulphide-bond formation occurred even when hydroxylation, and hence triple-helix formation, was inhibited. The presence of pro-alpha1- and pro-alpha2-components in a ratio of 2:1 in the disulphide-linked unhydroxylated procollagen isolated from tendon cells demonstrated that correct chain association occurs in the absence of hydroxylation. This observation is consistent with a model for the assembly of pro-gamma112-chains in which the recognition and selection of pro-alpha1-and pro-alpha2-chains in a 2:1 ratio are directed by the non-helical C-terminal extension peptides of tendon procollagen.

Anaerobiosis↗
PubMed1977

Studies on the biosynthesis, assembly and secretion of vitellogenin, an oestrogen-induced multicomponent protein.

1. The process by which the egg-yolk protein precursor vitellogenin is biosynthesized, assembled and secreted by Xenopus laevis (South African clawed toad) liver was studied. It was previously shown in other laboratories that vitellogenin contains the two egg-yolk proteins lipovitellin (mol.wt. 140 000) and phosvitin (mol.wt. 35 000). 2. Evidence is presented which shows that Xenopus liver microsomal fractions synthesize precursors of vitellogenin. These precursors were solubilized from the membranes with detergent and analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. This analysis indicated that there is only one precursor polypeptide, and this has mol.wt. approx. 200 000 +/- 20 000. This demonstrates that the egg-yolk proteins are translated as part of this larger polypeptide. 3. Experiments also demonstrate the existence of a microsomal proteinase which is able to cleave the precursor into smaller fragments. The nature of these fragments provided some indirect evidence that phosvitin and lipovitellin light chains are situated together within the precursor molecule. 4. These precursor data fit in well with structural studies on serum vitellogenin, since it has been shown that the latter protein consists of two identical subunits each with a mobility on sodium dodecyl sulphate/polyacrylamide gels identical with that shown by the microsomal precursor. This indicates that both the intracellular precursor and subunit of vitellogenin have similar (but not necessarily identical) molecular weights. 5. It was also shown that trypsin or chymotrypsin can cleave the serum vitellogenin into leucine- and serine-rich fragments which resemble lipovitellin and phosvitin respectively. Attention is, however, drawn to the fact that the serine-rich fragment is not identical with phosvitin, since it contains eight times more leucine than that expected for the authentic phosvitin molecule [Penning (1976) Ph.D. Thesis, University of Southampton].

Animals↗
PubMed1973

Studies on the assembly and secretion of a multicomponent protein. The biosynthesis of vitellogenin, an oestrogen-induced glycolipophosphoprotein.

1. Incorporation of [(32)P]P(i) and [(3)H]leucine into vitellogenin secreted in vitro by liver slices from oestrogen-treated Xenopus laevis is accompanied by a 2h lag; no lag is apparent for the incorporation into total tissue protein. 2. The addition of cycloheximide was found immediately to inhibit further incorporation of radioactive leucine into total tissue protein. The incorporation into secreted vitellogenin, however, continued for 2h after the addition of cycloheximide. 3. Pulse-labelling of liver slices with [(3)H]leucine for 30min, followed by a chase with a large excess of unlabelled leucine, resulted in the appearance of radioactivity in secreted vitellogenin from 90min after the end of the pulse period. 4. Evidence is presented which suggests that of the radioactivity from [(3)H]leucine incorporated into proteins by the liver of oestrogen-treated Xenopus some 70% is present in the single protein vitellogenin. 5. The incorporation of [(32)P]P(i) into vitellogenin followed a pattern identical with that found for [(3)H]leucine in the pulse-labelling experiments and this indicates that synthesis of the polypeptide chain and incorporation of P(i) are closely linked processes. 6. The cumulative evidence suggests that the 2h lag phase represents the time required for the assembly and secretion of this multicomponent protein.

Animals↗
PubMedDate not supplied

Test cells for use with anti-IgG sub-typing antisera in the antiglobulin test.

The preparation of test cells coated with specific IgG of known subclass is described. Such cells are required in the standardization of IgG subtyping reagents. At present, these test cells usually are prepared by coating cells with IgG myeloma paraproteins. However, these paraproteins may not be generally available and an alternative method is presented using more readily obtainable materials. Quantification of cell-bound IgG showed that the subclass did not affect the sensitivity of the antiglobulin test when using broad-spectrum anti-IgG and that the test cells produced had an optimal IgG coating. Reactions with subclass-specific antisera were however, considerably weaker that those obtained with broad-spectrum anti-IgG. A modified spin-layering technique for use with subclass-specific antisera is described.

ABO Blood-Group System↗