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Biomedical subjects

A F Williams

Publications and source records attributed to A F Williams.

At least 19 recordsLinked to original sources
PubMed1979

Purification with monoclonal antibody of a predominant leukocyte-common antigen and glycoprotein from rat thymocytes.

A leukocyte-common (L-C) antigen which can be dominant as an immunogen in rabbit anti-rat thoracic duct lymphocyte serum has been purified from rat thymocytes. Initially, an antigenic fragment of 100,000 apparent mol. wt. was prepared at 400 to 900-fold purification by lentil lectin affinity chromatography and gel filtration in deoxycholate. Mice were then immunized with this fraction, and a hybrid myeloma cell line secreting antibody to the L-C antigen was prepared by cell fusion. This antibody was used for affinity chromatography and gave pure L-C antigen at 1400-fold purification compared with thymocytes. The L-C antigen is a major membrane glyco-protein of rat thymocytes and has an apparent mol. wt. of 150,000 as determined by electrophoresis on polyacrylamide gels in sodium dodecyl sulfate. The antigen constitutes one of the three thymocyte glycoproteins which stain intensely for carbohydrate with periodic acid Schiff stain. It is present on greater than 95% of thymocytes, bone marrow cells and thoracic duct lymphocytes.

Animals↗
PubMed1979

Evaluation of the Tennessee Child Restraint Law.

In Tennessee a law came into force January 1, 1978 requiring parents to use child restraints properly when transporting their children who are less than four years old. Alternatively, the law permits children to be held in arms, a practice known to be hazardous rather than protective. Before and after the law went into force, observations were made of children in cars exiting from shopping centers in Knoxville and Nashville, Tennessee, and in Lexington and Louisville, Kentucky, an adjacent state not having a child restraint law. More than 80 per cent of Tennessee children observed in the fourth month the law was in force were not using child restraints anchored by seat belts, although use rates increased in Tennessee (8 to 16 per cent) to a greater extent than in Kentucky (11 to 15 per cent). Moreover, due to a large increase in children traveling in arms in Nashville, there was an increase in such travel in the two Tennessee cities studied (23 to 28 per cent) relative to a decrease in those studied in Kentucky (19 to 14 per cent).

Child Welfare↗
PubMed1978

T-lymphocyte heterogeneity in the rat: separation of functional subpopulations using a monoclonal antibody.

W3/25 antibody is the monoclonal product of a hybrid cell resulting from the fusion of a mouse myeloma cell line with spleen cells from a mouse immunized with rat thymocytes. Pure clones have been derived, and segregants free of parental myeloma chains have been isolated. Previous studies have shown that this antibody recognizes a subpopulation of T cells among rat thoracic duct lymphocytes. In the work reported here, three T-cell functions were assayed after separating rat thoracic duct lymphocytes on the fluorescence-activated cell sorter on the basis of labeling with W3/25 antibody. Two of the functional activities appeared to be completely segregated by this procedure. Thus, helper cell activity for an anti-hapten plaque-forming cell response was confined to the labeled population, whereas the allogeneic suppressive effect produced in a parental vector F1 adoptive transfer was mediated by cells in the unlabeled fraction. The third function, graft-versus-host activity, was almost entirely contained within the labeled subpopulation. It is concluded that the antigenic determinant recognized by the monoclonal antibody W3/25 is a differentiation marker for T-cell functional subpopulations.

Animals↗
PubMed1978

Glycoproteins and antigens of membranes prepared from rat thymocytes after lysis by shearing or with the detergent Tween-40.

In purification of cell surface antigens an efficient method for preparing membrane from large numbers of cells is needed. Such a method is described for preparing membranes from rat thymocytes after lysis in the non-ionic detergent Tween-40. Cell surface antigens were recovered at a yield of 30-50%, and a purification of 30-40-fold. By contrast enzyme markers for the other cell organelles were present in the membrane fraction in very low yield. The membrane obtained with the detergent method was compared with that resulting from the best of previously describes methods involving cell lysis by shearing. The detergent method compared favourably for simplicity as well as for yield and purification, and both membrane preparations contained similar protein and glycoprotein constituents. The main glycoprotein bands of membranes from thymocytes and thoracic duct lymphocytes were identified after polyacrylamide gel electrophoresis in dodecyl sulphate. In thymocyte membrane, three main bands at apparent molecular weights of 150 000, 84 000 and 25 000 were seen, and of these the 84 000 glycoprotein did not bind to the lentil lectin. In thoracic duct lymphocyte membrane the 25 000 glycoprotein was absent and a band at 95 000 was intensified in comparison with thymocytes.

Animals↗
PubMed1978

Molecular weights of the Thy-1 glycoproteins from rat thymus and brain in the presence and absence of deoxycholate.

1. The Thy-1 membrane glycoproteins from rat thymus and brain bound deoxycholate to 24% of their own weight as measured by equilibrium dialysis. The binding occurred co-operatively at the critical micelle concentration of deoxycholate, suggesting that the glycoproteins bind to a micelle, and not to the detergent monomer. 2. From sedimentation-equilibrium and deoxycholate-binding data the molecular weights of the glycoprotein monomers were calculated to be 18700 and 17500 for thymus and brain Thy-1 glycoprotein monomers were calculated to be 18700 and 17500 for thymus and brain Thy-1 glycoproteins respectively. The molecular weight of the polypeptide part of the glycoprotein is thus 12500. 3. In the absence of deoxycholate, brain or thymus Thy-1 glycoprotein formed large homogeneous complexes of mol. wt. 270000 or 300000 respectively. The sedimentation coefficient of these was 12.8 S. The complex was only partially dissociated by 4M-guanidinium chloride. 4. After cleavage of brain or thymus Thy-1 glycoprotein with CNBr, two peptides were clearly identified. They were linked by disulphide bonds and both contained carbohydrate. This cleavage suggests there is only one methionine residue per molecule, which is consistent with the above molecular weights and the known amino acid composition.

Alkylation↗
PubMed1978

Production of monoclonal antibodies to group A erythrocytes, HLA and other human cell surface antigens-new tools for genetic analysis.

Antibody-secreting hybrid cells have been derived from a fusion between mouse myeloma cells and spleen cells from a mouse immunized with membrane from human tonsil lymphocyte preparations. Hybrids secreting antibodies to cell surface antigens were detected by assaying culture supernatants for antibody binding to human tonsil cells. Six different antibodies (called W6/1, /28, /32, /34, /45 and /46 were analyzed. These were either against antigens of wide tissue distribution (W6/32, /34, and /46) or mainly on erythrocytes (W6/1 and W6/28). One of the anti-erythrocyte antibodies (W6/1) detected a polymorphic antigen, since blood group A1 and A2 erythrocytes were labeled while B and O were not. Antibodies W6/34, /45 and /46 were all against antigens which were mapped to the short arm of chromosome 11 by segregation analysis of mouse-human hybrids. Immunoprecipitation studies suggest that W6/45 antigen may be a protein of 16,000 dalton, apparent molecular weight, while W6/34 and /46 antigens could not be detected by this technique. Antibody W6/32 is against a determinant common to most, if not all, of the 43,000 dalton molecular weight chains of HLA-A, B and C antigens. This was established by somatic cell genetic techniques and by immunoprecipitation analysis. Tonsil leucocytes bound 370,000 W6/32 antibody molecules per cell at saturation. The hybrid myelomas W6/32 and W6/34 have been cloned, and both secrete an IgG2 antibody. W6/32 cells were grown in mice, and the serum of the tumor-bearing animals contained greater than 10 mg/ml of monoclonal antibody. The experiments established the usefulness of the bybrid myeloma technique in preparing monospecific antibodies against human cell surface antigens. In particular, this study highlights the possibilities not only of obtaining reagents for somatic cell genetics, but also of obtaining mouse antibodies detecting human antigenic polymorphisms.

Antibody Formation↗
PubMed1978

Evaluation of programs designed to increase the protection of infants in cars.

Three in-hospital educational programs for postpartum women, designed to increase the crash protection of infants in cars, were evaluated in comparison to a group that received no education. The programs consisted of (1) literature, plus making infant carriers readily accessible and convenient to purchase; (2) literature, plus a personal discussion, plus making infant carriers readily accessible and convenient to purchase; and (3) literature, plus the offer of a free infant carrier. The programs increased the extent to which infant carriers were used to transport babies in cars, but had little or no effect on the key outcome measure: use of infant carriers fastened by the car seat belt so that crash protection is provided. Rates of such use were low in all groups. It is concluded that ways of providing increased crash protection to infant and child travelers in addition to use of restraint systems requiring the active, voluntary cooperation of parents must be encouraged. "Passive" (automatic) protection techniques, such as air bags and vehicle interior modifications, have great potential in this regard.

Accident Prevention↗
PubMed1977

Estimation by radioimmunoassay of VH determinants (Aa1) associated with rabbit T lymphocytes.

A radioimmunoassay with specificity for the a1 allotype determinant of rabbit immunoglobulin (Ig) heavy chains was used for the quantitation of VH in detergent extracts of lymph node cells from a1a1/b4b4 rabbits. B cell-derived Ig in the same extracts was estimated with a radioimmunoassay specific for L-chain. About 2 X 10(5) molecules/cell was found by both assays when assuming a molecular weight of 1.5 X 10(5) dalton. Extracts prepared from lymphocytes depleted of B cells (surface Ig+ cells) were also found to contain corresponding amounts of a1 and L-chain, with values varying from about 10(3) to 10(4) molecules/cellmthe estimates were not influenced by the presence of inhibitors of proteolytic enzymes. Supernatants, obtained after keeping the lymphocytes in culture for 16 h, were analyzed by the same methods. Again, matching amounts of a1 and L-chain were found in supernatants from nonfractionated as well as from B cell-depleted populations. The results obtained indicate that T cells do not carry or produce an excess of a1 compared to L-chain, as would have been expected if the T cell antigen receptor carried the same variable region as the Ig heavy chain while being otherwise composed of nonimmunoglobulin-like structures.

Animals↗
PubMed1977

Differentiation antigens of the lymphocyte cell surface.

Many alloantigens and xenoantigens of lymphocytes are not found generally on other tissues, and this suggests that much of the lymphocyte cell surface is differentiated in comparison with other cell membranes. These differentiation antigens are probably molecules that mediate lymphocyte-specific functions, and are also of interest in that they provide markers for different lymphoid cell types and may be important as target antigens for immunosuppressive anti-(lymphocyte) sera. The purification of differentiation antigens will be important in allowing their molecular properties to be discovered, and will also lead to the production of strong, specific antisera that can be used in functional studies. Radioimmunoassays have been developed for the analysis of anti-(lymphocyte) sera, and these assays provide advantages in purification studies over other techniques. The features of these assays are discussed, and studies of differentiation antigens of rat lymphocytes are described. These include the purification and characterization of the rat Thy-1 antigen, and preliminary studies on two other rat lymphocyte differentiation antigens.

Absorption↗