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Biomedical subjects

J F Jones

Publications and source records attributed to J F Jones.

At least 91 records · Page 5Linked to original sources
PubMed1981

Postnatal endocardial fibroelastosis of the valve of the foramen ovale.

The valve of the foramen ovale of the heart changes at birth from a prenatal shunting device for the transseptal flow of systemic venous return to a postnatal active barrier to backflow of left atrial blood at higher pressure. To investigate the morphologic response to this functional change in the valve of the foramen ovale, we examined 200 hearts from embryos, fetuses and autopsy patients spanning over a millionfold range of heart weights (0.001 to 1,230 g). The relation of valve thickness to log heart weight was studied by a stepwise linear regression procedure that fitted the data to two linear regressions, one including observations made before birth and the other including observations made after birth. Analysis of variance tables demonstrated that the data are significantly better explained (p < 0.001) by two linear regressions that abruptly separate from one another at the time of birth than by a single linear regression. Histologic study showed that the prenatal valve consists of a thin myocardial layer with delicate endocardium. The postnatal thickening of the valve tissue occurs mainly by fibroelastotic thickening of the endocardium. The endocardial fibroelastosis of the valve develops after it closes and becomes a component of the left atrial wall. The observations support the concept that fibroelastosis is a nonspecific response of the lining of the cardiovascular system to increased mural tension.

Adolescent↗
PubMed1981

The effect of lymphocyte recovery on lymphocyte typing results.

This study examines the relationship between percent recovery of lymphocytes and T- and B-cell typing results. Lymphocytes were recovered from heparinized whole blood by density gradient centrifugation. T- and B-cells were enumerated by spontaneous sheep rosetting and direct fluorescent antibody staining for surface immunoglobulin, respectively. The findings indicate that at low recovery levels ( less than 80%) there is a significant increase in variability of lymphocyte typing results and a significant increase in IgG-bearing B-lymphocytes. Possible explanations for these findings are discussed. These results suggest that lymphocyte typing results should be interpreted in relation to recovery level and that recovery levels of greater than or equal to 80% are desirable.

Adolescent↗
PubMed1981

Fc (IgG) receptors on rat basophilic leukemia cells.

Receptors for IgG and IgE on rat basophilic leukemia cells (the 2H3 subline of RBL-IV) were detected by their ability bind IgE and IgG in fluorescence or radioactive assays. The 2H3 cells have approximately two-thirds as many receptors for IgG as for IgE. The IgE receptors bind monomeric IgE with high affinity and IgE binding is uninhibited by high concentrations of monomeric or oligomeric IgG. In contrast, the IgG receptors bind both (rabbit and rat) IgG and (rat) IgE. The affinity of IgG receptors for monomeric IgG and IgE is much lower than that of the IgE receptor for its ligand; binding of radiolabeled IgG or IgE to IgG receptors can be detected only with cross-linked oligomers. Although both receptors are sensitive to tryptic digestion than IgE receptors. Dual laser flow microfluorometric studies revealed that the numbers of IgG and IgE receptors per cell varied considerably among 2H3 cells and that the distributions of the 2 types of receptors were independent of each other. 2H3 cells released histamine through an IgE-mediated system, but cross-linked IgG, even in saturating amounts, did not elicit histamine release, nor have any effect upon IgE-induced release. Moreover, 2H3 cells would not mediate ADCC of IgG-coated chicken red blood cells.

Animals↗
PubMed1981

Antibody-dependent, cell-mediated cytolysis (ADCC) with antibody-coated effectors: rat and human effectors versus tumor targets.

We have previously described techniques that cause antibody molecules to remain bound to P388D1 cells for at least 18 hr, and enable these cells to lyse hapten-coated erythrocytes not sensitized with antibody. These methods collectively are called "franking." In this study, we have determined that these methods are applicable to other systems. We franked rat splenocytes and human peripheral blood leukocytes with rabbit anti-TNP antibody, and showed that they were capable of lysing TNP-tumor and erythrocyte targets (not coated with antibody) in a hapten-specific, antibody-dependent fashion. Both the mononuclear and the polymorphonuclear (PMN) leukocyte fractions of the human cells were capable of mediating lysis. Additionally, human leukocytes franked with rabbit antibody were stained with fluorescent goat anti-rabbit IgG Fab, and were analyzed for fluorescence by flow microfluorometry. Nearly all of the PMN cells and about one-half of the mononuclear cells had IgG on their surfaces after franking. Clearly, not all cells can be franked, but those that can retain significant numbers of antibody molecules (approximately 5 X 10(4), in the case of PMN cells) on their surfaces.

Animals↗
PubMed1980

Effect of 1-Aminocyclopropane-1-Carboxylic Acid on the Production of Ethylene in Senescing Flowers of Ipomoea tricolor Cav.

Application of 1-aminocyclopropane-1-carboxylic acid (ACC) to rib segments excised from flowers of Ipomoea tricolor Cav. resulted in the formation of C(2)H(4) in greater quantities than produced under natural conditions. The ability of ACC to enhance C(2)H(4) production was independent of the physiological age of the tissue and its capacity to synthesize C(2)H(4) without applied ACC. When ACC was fed to rib segments that had been treated with [(14)C]methionine, incorporation of radioactivity into C(2)H(4) was reduced by 80%. Aminoethoxyvinylglycine and aminooxyacetic acid inhibited C(2)H(4) production in rib segments of I. tricolor but had no effect on ACC-enhanced C(2)H(4) production. Protoplasts obtained from flower tissue of I. tricolor did not form C(2)H(4), even when incubated with methionine or selenomethionine. They produced C(2)H(4) upon incubation with ACC, however. ACC-dependent C(2)H(4) production in protoplasts was inhibited by n-propyl gallate, AgCl, CoCl(2), KCN, Na(2)S, and NaN(3). ACC-dependent C(2)H(4) synthesis in rib segments and protoplasts was dependent on O(2), the K(m) for O(2) being 1.0 to 1.4% (v/v). These results confirm the following pathway for C(2)H(4) biosynthesis in I. tricolor. methionine [selenomethionine] --> S-adenosylmethionine [selenoadenosylmethionine] --> ACC --> C(2)H(4).

Journal Article↗
PubMed1980

Terminal deoxynucleotidyl transferase development in the postnatal human thymus.

Terminal deoxynucleotidyl transferase activity was studied in 42 whole human thymuses of different ages (2 days to 70 years). The results indicate that enzyme activity is high perinatally, falls soon after birth, rises to maximal activity early in life, and falls thereafter. Enzyme activity in homologous thymocytes of 9 thymuses ranging from 2 days to 105 months was also determined. The relative enzyme activity (thymocyte/thymus) did not remain constant with age. These results suggest that age-related changes in thymus terminal transferase activity occur which do not reflect a simple coordinate regulation of thymocyte and non-thymocyte elements.

Adolescent↗
PubMed1980

The role of antibody multivalency in immune effector processes.

The preparation of covalently crosslinked oligomers of antibody molecules is described. It is shown that these oligomers can be used to study quantitatively the effects of multivalency on binding to cell surface Fc receptors. It is also shown that three effector systems differ in the ways in which they interact with multivalent immune complexes.

Allosteric Regulation↗
PubMed1980

The human thymus. II. Partial characterization of thymocytes separated on bovine serum albumin gradients.

Thymocyte populations from 9 postnatal normal human thymuses (9 mth to 14 yr) were partially characterized after separation from structural elements by mechanical dissociation or spontaneous release from short-term explant cultures. Populations were fractionated on a 17 to 35% discontinuous bovine serum albumin (BSA) gradient and fractions characterized by morphology, pulse labeling index, spontaneous incorporation of labeled thymidine and uridine, E-rosetting ability (4 degrees C) and terminal deoxynucleotidyl transferase (TdT) activity. The following observations were made: (1) the gradient distribution of lymphocytes followed a bell-shaped curve, but with a greater percentage of less dense cells in older thymuses; (2) 60 to 80% of lymphoblasts (3-7% of total thymocytes) were in the 21-23% BSA fractions; (3) spontaneous incorporation of labeled thymidine and uridine was highest in 21-23% fractions; (4) 40 to 55% of lymphoblasts were in active DNA synthesis; (5) less than 50% of lymphocytes from the 17 to 21% fractions formed E rosettes compared to 95% of unfractioned cells; (6) one or two distinct peaks of TdT activity were identified; four thymuses had one peak in the small/medium lymphocyte fractions, whereas in two specimens a second peak was seen. Enrichment of lymphocyte subpopulations of the human thymus for immature cells may aid in further delineation of thymic function in developing man.

Aging↗
PubMed1980

The human thymus. I. Partial characterization of nonlymphoid cells.

Human thymus was disrupted by mechanical and enzymatic techniques yielding tissue fragments and single-cell suspensions. Cell types and their distribution were determined before and after density separation. Single-cell suspensions produced by both separation procedures yielded comparable percentages of lymphoid and monocytic cells, whereas only the enzyme-treated tissue yielded epithelial cells. Less than 1% of all monocytic cells were mature. Monolayer cultures were established from fragments as well as unfractionated cells and gradient fractions. Analysis of these cultures showed that: (1) gradient separation of mechanically-prepared cell suspensions produced cultures enriched for macrophages, while epithelial cell cultures could be produced from fractionated enzyme treated tissue; (2) spindle-shaped cells may be fibroblasts or epithelial cells; (3) explant cultures have a growth pattern characteristic of other epithelial cells in vitro; (4) macrophages constitute a definite population of explanted cells and their percentages increase with time in culture; (5) macromolecular synthesis by epithelial cells in culture may be donor age dependent. Nonlymphoid cells of the human thymus can be identified by a variety of separation techniques and after monolayer culture. Characteristics of these cells are defined which may affect cell-cell interaction studies of the thymus.

Aging↗
PubMed1980

Antibody-dependent cell-mediated cytolysis (ADCC) with antibody-coated effectors: new methods for enhancing antibody binding and cytolysis.

When P388D1 cells are incubated with anti-TNP IgG antibody and centrifuged through a mixture of dibutylphthalate and bis-(2-ethylhexyl)phthalate (1.5:1), large amounts of antibody remain cell bound for at least 20 hr after washing. Incubating cells with antibody in various concentrations of polyethylene glycol also enhances antibody binding compared with control cells incubated with antibody alone. P388D1 cells coated with anti-TNP antibody are potent killers of TNP-conjugated chicken erythrocytes (not coated with antibody). The cytolytic activity increases in proportion to the amount of antibody bound by the effector cells. Lysis is antibody dependent and hapten inhibitable. When mediated by antibody-coated effectors, lysis is less suceptible to inhibition by aggregated IgG than lysis of antibody-coated cells mediated by untreated effector cells.

Animals↗
PubMed1979

Spontaneous alternation in chicks using social reward.

Two experiments examining spontaneous alternation in young white Leghorn chicks are reported. In Experiment I chicks (20 per group) run in a T-maze for 4 trials to social reward displayed alternation of responses, whereas nonrewarded chicks did not alternate. In Experiment II socially rewarded chicks (20 per group) again showed reliable alternation of responses whereas food, water, and nonrewarded chicks did not alternate. These data support the premise that spontaneous alternation behavior has some phyletic generality under optimum conditions, although the mechanisms which control it may differ across species.

Animals↗