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Biomedical subjects

A L Chapman

Publications and source records attributed to A L Chapman.

At least 19 recordsLinked to original sources
PubMed2001

Epstein-Barr virus-specific cytotoxic T lymphocyte responses in the blood and tumor site of Hodgkin's disease patients: implications for a T-cell-based therapy.

Approximately 40% of Hodgkin's disease (HD) cases carry EBV in the malignant Hodgkin-Reed Sternberg (H-RS) cells, with expression of viral latent membrane proteins (LMPs) 1 and 2. These viral proteins are targets for CTLs in healthy EBV carriers, and their expression in EBV-associated HD raises the possibility of targeting them for a CTL-based immunotherapy. Here we characterize the CTL response to EBV latent antigens in both the blood and tumor-infiltrating lymphocytes of HD patients using two approaches: (a) in vitro reactivation of CTLs by stimulation with the autologous EBV-transformed lymphoblastoid cell line; and (b) an enzyme-linked immunospot assay to quantify frequencies of CTLs specific for known LMP1/2 epitopes. We detected EBV-specific CTLs in blood and biopsy samples from both EBV-negative and EBV-positive HD patients. However, as in healthy EBV carriers, LMP-specific CTL precursors occurred only at low frequency in the blood of HD patients, and with the exception of one EBV-negative HD case, were undetectable in the tumor. These data give rise to two considerations: (a) they may explain why EBV-positive tumor cells persist in the presence of an existing EBV-specific immune response; and (b) they provide a rationale for selectively boosting/eliciting LMP-specific CTL responses as a therapy for EBV-positive HD.

Adolescent↗
PubMed2000

Comparison of mono- and dichlorinated tyrosines with carbonyls for detection of hypochlorous acid modified proteins.

Hypochlorous acid is a potent oxidant capable of oxidizing and chlorinating proteins. Based on its indiscriminant reactivity, it is proposed to play a major role in tissue damage associated with a range of inflammatory diseases. We have determined the relative tendencies for formation of protein carbonyls, chlorinated tyrosine residues, and epitopes recognized by an antibody raised against hypochlorous acid oxidized protein (HOP-1) when albumin is treated with hypochlorous acid. We have also tested the specificity of the HOP-1 antibody by measuring how effectively it recognizes proteins oxidized by hypobromous acid. 3-Chlorotyrosine, along with a new marker of hypochlorous acid dependent protein modification, 3, 5-dichlorotyrosine, was formed at the lowest doses of hypochlorous acid that were capable of generating protein carbonyls. Comparatively high doses of hypochlorous acid were needed to generate epitopes recognized by HOP-1, which were also produced by hypobromous acid. Our study demonstrates that it is advantageous to measure protein carbonyls and HOP-1 epitopes in conjunction with chlorinated tyrosines when attempting to identify the oxidants responsible for inflammatory tissue damage.

Animals↗
PubMed1998

Comparison of human red cell lysis by hypochlorous and hypobromous acids: insights into the mechanism of lysis.

Human red blood cells are lysed by the neutrophil-derived oxidant hypochlorous acid (HOCl), although the mechanism of lysis is unknown. Hypobromous acid (HOBr), a similarly reactive oxidant, lysed red cells approx. 10-fold faster than HOCl. Therefore we compared the effects of these oxidants on thiols, membrane lipids and proteins to determine which reactions are associated with lysis. There was no difference in the loss of reduced glutathione or membrane thiols with either oxidant, but HOBr reacted more readily with membrane lipids and proteins. Bromohydrin derivatives of phospholipids and cholesterol were seen at approx. one-tenth the level of oxidant than chlorohydrins were. However, these products were detected only with high concentrations of HOCl or HOBr, which caused instant haemolysis. Membrane protein modification occurred at much lower doses of oxidant and was more closely correlated with lysis. SDS/PAGE analysis showed that band 3, the anion transport protein, was lost at the lowest dose of HOBr and at the higher concentrations of HOCl. Labelling the red cells with eosin 5-maleimide, a fluorescent label for band 3, suggested possible clustering of this protein in oxidant-exposed cells. There was also irreversible cross-linking of all the major membrane proteins; this reaction occurred more readily with HOBr. The results indicate that membrane protein modification is the reaction responsible for HOCl-mediated lysis. These effects, and particularly cross-link formation, might result in clustering of band 3 and other membrane and cytoskeletal proteins to form haemolytic pores.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1998

Epstein-Barr virus in Hodgkin's disease.

Epstein-Barr virus (EBV), a B-lymphotropic herpesvirus widespread in human populations, is carried by most individuals as an asymptomatic lifelong infection. Much progress has been made in our understanding of virus infection/persistence, and in the role of the cytotoxic T lymphocyte response in control of that infection. This same virus is linked to several malignancies, including endemic Burkitt's lymphoma, post-transplant lymphoproliferative disease and to many cases of Hodgkin's disease (HD). Recent evidence showing that HD, like the other EBV-associated lymphomas, is of B-cell origin suggests that the pathogenesis of these malignancies may share more common ground than previously thought. The biology and cytotoxic T-cell control of primary and persistent EBV infection, and the links between EBV and all three lymphomas are reviewed. The expression of viral antigens in EBV-positive HD raises the possibility of developing tumour immunotherapy, using relevant components of the EBV-specific T-cell response; progress to date, and future prospects for immune control of EBV-positive HD are discussed.

Antigens, Viral↗
PubMed1996

Investigation of wool protein heterogeneity using two-dimensional electrophoresis with immobilised pH gradients.

The heterogeneity of intermediate filament proteins (IFP) from wool has been investigated using two-dimensional polyacrylamide gel electrophoresis with immobilised pH gradients in the first dimension. The charge heterogeneity has been confirmed with some of the IFP separated as a string of spots with similar molecular weight, but markedly different in isoelectric point (pI). The molecular weight and pI distribution of the string of IFP changed after treatment with alkaline phosphatase, indicating that some of the heterogeneity is caused by phosphorylation.

Alkaline Phosphatase↗
PubMed1990

A role for cAMP-dependent protein kinase A in early Dictyostelium development.

In Dictyostelium, cAMP functions as an extracellular regulatory molecule that controls aggregation, expression of a number of classes of genes, and cellular differentiation by binding to cell-surface receptors that activate intracellular signal transduction pathways. To investigate possible roles for intracellular cAMP, we have overexpressed the wild-type mouse type-I regulatory subunit (RI) of cAMP-dependent protein C (PKA) in Dictyostelium cells, as well as mutant forms of the subunit that are altered in their ability to bind cAMP. We show that overexpression of a mutated RI, which lacks both cAMP-binding sites and presumably forms a complex with the endogenous Dictyostelium catalytic subunit that cannot be activated by cAMP, results in cells that do not aggregate or express sets of genes that are normally induced in the multicellular stages. Transformations that express the mutant subunit at low levels show no observable phenotype. We show that these cells can respond to pulses of cAMP and activate cAMP receptor/G protein-mediated processes, including the activation of adenylate and guanylate cyclases and the induction of a class of genes known to be regulated through the receptor-mediated pathways; however, the cells do show an altered pattern of expression of other genes normally active during the preaggregation/interphase and aggregation stages. Of interest is a substantial overexpression of the developmentally regulated PDE mRNA. Cell lines carrying constructs encoding the wild-type subunit or mutant subunits lacking one of the two binding sites show no visual phenotype. The results suggest that PKA-mediated functions, presumably controlled by increases in intracellular cAMP, are essential for Dictyostelium aggregation.

Adenylyl Cyclases↗
PubMed1985

X-ray microanalysis of chloride in nails from cystic fibrosis and control patients.

Nail clippings from 60 individuals were examined. There were 34 "old" (greater than 16 years) controls, 16 "young" controls and 10 CF patients. In regard to elements found, Si and Al were considered as exogenous contamination. Other elements examined were variable in both control and CF. Examination of the Cl levels among the 3 groups showed a highly significant difference between the mean Cl integral values of the young controls (619 integral) and the CF patients (2956 integral). The results of the older control population ranged from 0-905 integral with a mean of 269 integral. We found no age or sex difference in the amount of Cl or any other element from either the CF or control population. Results show that the x-ray energy dispersive system (EDS) is very useful in studying the Cl in nails. We found that examination of nails frozen in liquid nitrogen followed by fracturing without prior washing was the preferred method. Although the results of this study clearly show statistically the value of EDS analysis of Cl in the diagnosis of CF, we must await further study of a larger group of patients to determine its usefulness in evaluating individual patients, particularly newborns.

Adolescent↗
PubMed1984

Multinucleation of cultured canine epithelial and lymphoma cell lines.

The frequency distribution patterns of monuclear and multinuclear giant cells were determined for two canine lymphoma cell lines (DT-5 and 11028), and a normal canine kidney epithelial cell line (DK). The proportion of multinuclear cells in the DK line (1.53%) was approximately twice those of the DT-5 (0.75%) and 11028 (0.73%) cell lines. The observed frequency distributions of cells with single and various numbers of multiple nuclei were compared to Poisson distributions using the chi-square test. For each cell line, the number of cells with three or more nuclei far exceeded the number predicted by the Poisson distribution. Hence, the occurrence of multinuclear cells in these canine cell lines does not follow a random distribution pattern. Possible explanations for the nonrandom accumulation of multinuclear giant cells are discussed.

Animals↗
PubMed1983

Level and temporal pattern of naturally cytolytic cells during acute Graft-versus-Host Disease (GVHD) in the rat.

The purpose of the present study was to determine the level of nonadherent lymphoid cells from Graft-verus-Host Disease (GVHD) rats able to naturally kill (NK/NC cells) various solid tumor or lymphoma cells in vitro. Acute lethal GVHD was produced in either newborn or adult (DA x LEW)F1 rats by iv injection of LEW spleen and lymph node (LN) cells. Controls received the same dose of syngeneic cells. At 7, 14, and 21 days after cell injection, the ability of non-adherent mononuclear cells from the LN, spleen, peripheral blood lymphocytes (PBL), marrow, and thymus to kill 51Cr-labeled dog (DT-5) lymphoma, and undifferentiated sarcoma (11031) or human (HUS-2) sarcoma cells in vitro was determined. Only spleen and marrow of controls caused significant 51Cr release from the target cell lines. However, LN, spleen, marrow, PBL, and thymus from neonates and adults with GVHD of 7 days duration caused greater release from all targets than controls (P less than 0.05-0.001). By Day 14 the level of 51Cr released was significantly less than controls except for the values from LNs and thymus which remained elevated. By Day 21 all lymphoid compartments exhibited a decrease in NK/NC cells. Thus, early during acute GVHD, there is an activation and/or expansion of NK/NC cells while later-stage GVHD rats have depressed NK/NC levels.

Acute Disease↗
PubMed1983

Mucolipidosis I.

A case of mucolipidosis I had clinical and histopathologic features that were a combination of changes found in both mucopolysaccharidoses and sphingolipidoses. Corneal clouding, spokelike cataracts, tortuous conjunctival and retinal vessels, and strabismus were clinical findings. Histopathologically, there were inclusion vacuoles similar to those seen in mucopolysaccharidoses; lamellar bodies typical of sphingolipidoses were rare. These vacuoles were seen in conjunctival and corneal epithelium and fibrocytes, conjunctival and retinal vessel endothelium, and all retinal cell layers.

Conjunctiva↗
PubMed1982

Studies of a human mesothelioma.

Abdominal fluid from a patient with mesothelioma was cultured in vitro, and a cell line designated JMN was established. This cell line has undergone more than 100 passages. Electron microscopic, karyotypic, and heterotransplantation studies as well as the capability of collagen synthesis by this cell line indicated that it is of malignant mesothelial origin. The cell line has proved very useful for the isolation of human pathogenic viruses.

Abdominal Neoplasms↗
PubMed1981

The relationship of herpesvirus to carcinoma of the prostate.

A laboratory based epidemiologic study was done to determine the possible relationship of herpesvirus type 2 to carcinoma of the prostate. A total of 305 patients (224 with benign prostatic hypertrophy and 81 with prostatic carcinoma) who underwent transurethral resection of the prostate was studied. Viral cultures were obtained from urethral swabs and urine preoperatively. Prostatic tissue removed at operation was grown as tissue explants, using a monolayer cell culture technique, and examined by specific immunofluorescence and electron microscopy for evidence of herpesvirus type 2. The sera of the patients also were tested for specific antibody to herpesvirus type 2 by the indirect hemagglutination inhibition test. Although herpesvirus was not isolated 5 per cent of the patients had evidence of herpesvirus type 2 antigen in prostatic tissues by specific immunofluorescence. Electron microscopy failed to reveal the presence of viral particles. There was an increased prevalence of herpesvirus type 2 antibody in patients with carcinoma of the prostate compared to the controls with benign prostatic hypertrophy (p less than 0.05). Although marital status was similar the patients with prostatic cancer tended to marry at an earlier age, have more children, more sexual partners and more exposure to prostitutes than their counterparts with benign prostatic hypertrophy. The demonstration of specific herpesvirus type 2 antibody in patients with prostatic cancer supports an etiologic role for herpesvirus type 2 but further studies are needed to describe more definitively the relationship since the indexes of sexual activity are remarkably high in both groups.

Antibodies, Viral↗
PubMed1980

Cell cycle kinetics of uninfected and feline leukemia virus-infected canine lymphoma cell lines: effects of methotrexate treatment.

The cell cycle kinetics of uninfected and feline leukemia virus-infected canine lymphoma cell lines were determined by autoradiography (PLM method) as follows: DT-5: generation time (TC), 15.2 h; pre-synthetic gap phase (TG1), 3.2 h; DNA-synthetic phase (TS), 8.2 h; post-synthetic gap ph se (TG2), 3.3 h; visible mitotic phase (TM), 0.5 h. 11028: TC, 13.6 h; TG1, 1.9 h; TS, 7.7 h; TG2, 3.4 h; TM, 0.6 h. 11028+FeLV (11028 productively infected with feline leukemia virus): TC, 11.2 h; TG1, 0.2 h; TS, 8.3 h; TG2, 2.1 h; TM, 0.6 h. Exposure of the lymphoma cell lines to methotrexate (MTX) in vitro produces dose-related increases in cellular volume, associated with reductions in cellular proliferation. The relative sensitivities of these cell lines to MTX, measured by the ID50 MTX concentrations for DT-5, 11028, and 11028+FeLV are 118 nM, 122 nM, and 28 nM respectively. The cell kinetic effects of the ID50 MTX concentrations added to cultures of lymphoma cells pulse-labeled with tritiated thymidine are an approximately 2-h prolongation of TC, attributable to a lengthening of TS, with other cell cycle phases not significantly altered. These cell lines are highly tumorigenic when transplanted into the cheek pouches of immunosuppressed hamsters, with inocula of 10(4) cells producing rapidly growing, well vascularized tumors.

Animals↗
PubMed1979

Scanning electron microscopy of bronchiolar neuroepithelial bodies in neonatal mouse lungs.

Scanning electron microscopy of the bronchiolar neuroepithelial bodies (NEB's) in the neonatal mouse lungs was undertaken and correlated with the accompanying transmission electron microscopy. The NEB's appeared as isolated organoids along the entire length of the bronchioles, and often were located at the branching points. The boundary of the NEB's was outlined by the ciliated and Clara cells. Both granulated cells and modified Clara cells participated in the formation of the NEB. The modified Clara cells covered most of the surface of the NEB leaving only small oval areas for the exposed surfaces of the specialized cells which contained numerous cytoplasmic granules. Short and regular microvilli projected from the exposed surfaces of the granulated cells, while only sparse microvilli of irregular length were seen on the surfaces of the modified Clara cells. This scanning electron microscopy of the NEB's further established these organoids as separate morphological entities. In addition, the findings that the NEB's could be easily identified with the scanning electron microscope and subsequently dissected out for further studies would help future investigations of their functions which are not clearly known.

Animals↗
PubMed1978

Transformation of human embryo cells with the use of cell-free extracts of a human rhabdomyosarcoma cell line (HUS-2): brief communication.

Cell-free extracts of the human rhabdomyosarcoma cell line HUS-2 caused the transformation of human embryo fibroblasts. This transformation included morphologic alteration, karyotypic change, and an increase in culture longevity. With the use of sex markers, multiple karyotypes confirmed that the human embryo fibroblasts were transformed, and the use of cell-free material further suggested the presence of a transforming virus. RNA-dependent DNA polymerase activity in a particle with a specific gravity of 1.16 g/cm3 indicated the presence of an RNA type C virus. Evidence also suggested that the known mammalian type C viruses, routine cytopathic effect-inducing viruses, or mycoplasma were not the agents responsible for the transformation. That both the donor (HUS-2) and converted (HUE-T) cell lines cross-reacted with antisera prepared against HUE-T indicated a common antigen arising in the process of conversion of HUS-2 cells to HUE-T cells.

Animals↗