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Biomedical subjects

A F Williams

Publications and source records attributed to A F Williams.

At least 235 records · Page 13Linked to original sources
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↗
PubMed1977

Quantitative serological analysis of a rabbit anti-rat lymphocyte serum and preliminary biochemical characterisation of the major antigen recognised.

Rabbit antisera to rat thoracic duct lymphocytes were examined by absorption analysis with quantitative radioimmunoassays to determine the tissue distribution of the antigens recognised and the amount of antibody against different specificities. Seven of eight sera were remarkably specific for leucocytes and one serum was analysed in detail. In this serum about 70 per cent of the antibody was leucocyte specific and most was against determinants on thymocytes, bone marrow cells, peripheral lymphocytes, and macrophages. This specificity is referred to as the leucocyte-common antigen. Smaller amounts of antibody were specific for antigens on peripheral lymphocytes but not thymocytes, and this could be subdivided into two antigens, one present on bone marrow cells and the other not. For preliminary biochemical analysis of the leucocyte-common antigen, thymocyte membrane was solubilized in deoxycholate. The homogeneity and apparent size of the antigen was determined by gel filtration and zone sedimentation on sucrose gradients. The activity behaved as a single component with the following hydrodynamic properties: sedimentation coefficient, 5.9S; partial specific volume, 0.71 ml/g; and Stokes radius, 7.5 nm. The molecular weight (including any bound deoxycholate) was calculated to be 172,000 and the frictional ratio 2.05. All activity bound to a lentil lectin affinity column and was eluted by methyl alpha-D-glucopyranoside, suggesting that the antigen is a glycoprotein.

Animals↗
PubMed1976

Factors in the initiation of bicycle-motor vehicle collisions.

In this study, 888 injury-producing bicycle-motor vehicle collisions were examined. On the basis of the movements of the vehicles involved, the bicyclist or the bicycle or both was probably responsible for the initiation of more than three fourths of the collisions. Bicyclist age was strongly related to probable responsibility for the collision. Through age 12, nine out of ten bicyclists were probably responsible for the collision; above age 12, probable responsibility decreased in proportion to age; and only 34% of the bicyclists aged 25 years or older were probably responsible. Collisions involving bicyclists in various age groups differed considerably in where, when, and how they occurred. The movements of the vehicles primarily involved in the initiation of the collisions were evaluated in terms of counter-measure planning.

Accidents, Traffic↗
PubMed1976

Observed child restraint use in automobiles.

Visual observations were made on restraint use in occupants of 5,050 automobiles containing at least one passenger less than 10 years of age, and short interviews were conducted with the drivers. Ninety-three percent of passengers less than 10 years old were not restained. Eighty-nine percent of passengers 10 or older and 78% of the drivers were not restained. Sixteen percent of child motor vehicle restraint devices observed were not used, and 73% of those in use were not used correctly. Use of such devices declined sharply after age 1. Although child passengers were more likely to be restained if the driver was restrained, more than 75% of the children were not restrained when the driver was, even if the driver was the child's parent.

Accidents, Traffic↗
PubMed1976

Many cells in rat bone marrow have cell-surface Thy-1 antigen.

Thy-1.1 and Thy-1 xenoantigenic determinants were detected at the cell surface of many rat bone marrow cells. The absorptive capacity of bone marrow cells was 6-10% of that of thymocytes for Thy-1 antigenic determinants, and 30-45% of rat bone marrow cells were specifically labeled with anti-Thy-1 antibody as detected by autoradiography. Thus, while mice and rats are similar in having large amounts of Thy-1 in brain and thymocytes, they differ in that the rat lacks the antigen in most peripheral T cells and expresses it in a large number of bone marrow cells; the opposite is true in the mouse.

Animals↗
PubMed1975

The presence of IgA on the surface of rat thoractic duct lymphocytes which contain internal IgA.

The presence of lymphocytes with internal IgA among cells from rat thoracic duct lymph wdy. The number of cells detected was greater in animals kept in a convential animal house compared with those maintained under specific pathogen-free conditions. Thoracic duct lymph from B rats and adult thymectomized rats also contained cell with internal IgA. The surface Ig of the IgA-containing cells was studied using a double-labeling technique with (126I) anti-Ig to detect surface Ig, and fluorescein-conjugated anti-IgA in large amounts, but very little IgM and no surface IgG2. The surface IgA was not acquired passively.

Animals↗
PubMed1975

Antigens on mouse and rat lymphocytes recognized by rabbit antiserum against rat brain: the quantitative analysis of a xenogeneic antiserum.

Quantitative assays for measuring the binding of xenogeneic antiserum to dispersed cell suspensions are described. Cells were incubated with unlabeled xenogeneic antiserum and the antibody bound measured indirectly by a second binding step with 125I-labeled anti-immunoglobulin antibody. This indirect radioactive binding assay was calibrated by measuring, with a radioimmunoassay, the true amount of antibody bound in the first step. With these methods one can measure the strength of antisera, quantitate the number of antigenic sites, and partially differentiate determinants being recognized on cell surfaces. The binding of rabbit anti-rat brain antiserum to rat and mouse lymphocytes was analyzed in detail. After absorption of the antiserum with rat liver, the antibody remaining recognized lymphocyte antigens that were distributed among various rat and mouse tissues in quantities identical to Thy-1.1 antigen. Thus, at saturation, 670 000 Ig molecules from liver-absorbed rabbit antiserum were bound per rat thymocyte, and the antiserum bound to 90%, 21%, 4% and 2% of rat thymocytes, spleen, lymph node and thoracic duct lymphocytes, respectively. With mouse tissues, 90% 24% and 50% of thymocytes, spleen and lymph node cells, respectively, were labeled. In rat brain the concentration of xenoantigen increased with age, while in thymocytes the full adult amount was present at birth. Three antigenic determinants could be defined with the liver absorbed rabbit antiserum: the Thy-1.1 antigen, a rat specific antigen and an antigen cross-reacting between rat and mouse tissues. All 3 may be on the Thy-1 molecule. The anti-brain antiserum contained about 0.05 mg/ml of antibody specific to these xenoantigens.

Age Factors↗