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Biomedical subjects

C A Noonan

Publications and source records attributed to C A Noonan.

At least 19 recordsLinked to original sources
PubMed1993

Okadaic acid inhibits dephosphorylation of cytoplasmic p53 during lymphocyte activation.

A competition radioimmunoassay specific for conserved Domain V of p53 revealed that Domain V was masked in highly phosphorylated cytosolic p53 of resting T lymphocytes and unmasked through dephosphorylation during lymphocyte activation. Phosphatase type 2A was shown to act upon immunopurified p53 in a manner that increased the immunoreactivity of the molecule in the Domain V RIA. Treatments of T cells with okadaic acid (1nM) prior to addition of Concanavalin-A/serum inhibited completely the dephosphorylation of cytosolic p53 observed to occur within 10-20min of stimulation. Brief exposure of T cells to okadaic acid during the first hour of activation by mitogens produced increased rates of cellular proliferation. Sustained inhibition of the dephosphorylation of cytoplasmic p53 in cells undergoing mitogenic stimulation may affect adversely the ability of p53 to exert its anti-proliferative effect and could contribute to unregulated cell growth.

Amino Acid Sequence↗
PubMed1993

Low serum alpha-fetoprotein level in patients with hepatocellular carcinoma as a predictor of response to 5-FU and interferon-alpha-2b.

BACKGROUND: A Phase II clinical trial was conducted to evaluate the efficacy of intravenous fluorouracil (5-FU) and subcutaneous recombinant interferon-alpha-2b (rIFN-alpha-2b) in the treatment of hepatocellular carcinoma (HCC) and to define factors that might be predictive of a response to treatment. METHODS: Twenty-nine patients were registered on the protocol. 5-FU was administered as a continuous intravenous (i.v.) infusion (dose = 750 mg/m2) for 5 consecutive days. rIFN-alpha-2b was administered subcutaneously (SC) (dose = 5 x 10(6) um/m2) once a day on days 1, 3, and 5 of the 5-FU infusion. The treatment was repeated at 14-day intervals. Responses were assessed at the end of one course of therapy, which was equivalent to four treatments. RESULTS: Of the 28 patients evaluable for response, 5 (18%) had a partial response, and 1 (4%) had a minor response. Responses lasted from more than 2 to more than 24 months (median, 11.5 months). Ten (36%) patients experienced no response, and 12 (43%) had progressive disease. The 6 responders were part of a group of 16 patients who had pretreatment levels of serum alpha-fetoprotein (AFP) of 50 ng/ml or less and a group of 8 whose tumors involved 50% or less of the liver parenchyma. Mucositis, which occurred in 54% of the patients, was the most common toxicity associated with the treatment regimen. Diarrhea and dermatitis were observed in 16% and 17% of the patients, respectively; fatigue, thrombocytopenia, granulocytopenia, neurologic toxicity, and nausea and vomiting were not commonly seen. CONCLUSIONS: The regimen of i.v. 5-FU and SC rIFN-alpha-2b was well tolerated and induced durable partial response in 31% (5 of 16) of patients with HCC who had low levels of serum AFP and in those with 50% or less of liver replacement. In contrast, the treatment regimen was ineffective in patients with HCC who had high levels of serum AFP or extensive liver disease.

Adolescent↗
PubMed1993

The envelope glycoprotein of human immunodeficiency virus type 1 stimulates release of neurotoxins from monocytes.

Mononuclear phagocytes infected with human immunodeficiency virus 1 (HIV-1) produce soluble factors that kill neurons in culture. To define the molecular events that lead to neuron killing, HIV-1 proteins were tested for the ability to trigger release of neurotoxins from human monocytes and lymphocytes. None of the recombinant-derived HIV-1 proteins examined (reverse transcriptase, protease, gag, nef, or gp120) were directly neurotoxic at concentrations from 100 pM to 10 nM. The envelope glycoprotein gp120 did, however, stimulate both isolated human blood monocytes and the monocytoid line THP-1 (but not lymphocytes or the lymphoid cell line H9) to discharge neurotoxic factors. These toxins consisted of heat-stable, protease-resistant molecules (< 500 Da) that copurified with neurotoxins from HIV-1-infected THP-1 cells and were blocked by antagonists to N-methyl-D-aspartate receptors. Release of neurotoxins through gp120 stimulation involved monocytoid CD4 receptors because toxin production could be inhibited either by a monoclonal antibody to the CD4-binding region of gp120 or by soluble CD4 receptors. Alternatively, production of neuron-killing factors could be induced with a peptide from the CD4-binding region of gp120. These data show that the HIV-1 envelope glycoprotein alone can stimulate neurotoxin release by binding to CD4 receptors of mononuclear phagocytes. Such neurotoxic factors may, in turn, contribute to the central nervous system dysfunction associated with HIV-1 by acting on neurons through N-methyl-D-aspartate receptors.

Animals↗
PubMed1993

Southern-blot analysis and simultaneous in situ detection of hepatitis B virus-associated DNA and antigens in patients with end-stage liver disease.

To gain new insights into the pathogenesis of hepatitis B virus-induced chronic liver disease, we have used nonisotopic in situ detection methods for the simultaneous analysis of hepatitis B virus DNA and antigens at the single-cell level. Paraffin-embedded liver specimens from 23 cirrhotic patients (12 HBsAg positive and 11 HBsAg negative) who underwent liver transplantation were evaluated by in situ hybridization with a digoxigenin-labeled DNA probe and digoxigenin detection system and by immunohistochemistry with an enhanced biotin-streptavidin technique. DNAs extracted from liver and serum specimens were analyzed by Southern- and slot-blot hybridization, respectively. Using the in situ techniques, we detected hepatitis B virus-specific DNA and antigens in 11 of 12 HBsAg-positive patients and in none of the 11 HBsAg-negative individuals. Replicative intermediates of hepatitis B virus DNA were detected by Southern-blot analysis in the same 11 HBsAg-positive patients, 6 of whom had no serological markers of hepatitis B virus replication. Therefore a good correlation was found between the results obtained by the in situ and Southern-blot hybridization analyses of tissue specimens. However, a lack of correlation was found between serum- and tissue-associated markers of viral replication. In addition, the simultaneous in situ detection analyses revealed that some hepatocytes containing high levels of viral DNA were devoid of detectable HBcAg, suggesting a mechanism by which the virus may escape immunological surveillance.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Southern↗
PubMed1992

Hepatitis B virus. New and evolving issues.

Recent developments in molecular biology have advanced our understanding of the pathogenesis of HBV-induced disease. New data derived from the molecular analysis of clinical material have begun to bridge the gap between bench research and the clinical arena. In this review, we consider topics that have relevance to clinical management and that have not been summarized in the recent literature. The recent advances that have been made in the areas of HBV variants, in vitro cell culture systems, and extrahepatic infection are discussed in greater detail.

Animals↗
PubMed1992

Simultaneous detection of HBV-specific antigens and DNA in paraffin-embedded liver tissue by immunohistochemistry and in situ hybridization using a digoxigenin-labeled probe.

To understand the pathogenesis of HBV infection at the single cell level, we have established a sensitive, specific and reproducible method for the simultaneous in situ detection of HBV-specific nucleotide sequences and antigens in paraffin-embedded liver tissue using nonradioactive hybridization and immunohistochemical techniques. Liver sections were stained for HBsAg or HBcAg by immunohistochemistry (IHC) using an enhanced biotinstreptavidin technique. Following immunohistochemical staining of the liver sections, in situ hybridization (ISH) was performed on the same section using a digoxigenin-labeled, HBV-specific probe. Specific hybridization was detected using an anti-digoxigenin, Fab fragment-alkaline phosphatase conjugate. This simultaneous assay permits the subcellular localization of HBV DNA and antigens with excellent preservation of tissue morphology and absence of background staining. In addition, the types and percentage of cells harboring HBV in the tissue can be determined. Although both reactions are detected by immunohistochemical methods, the application of a dual detection system using two different color reagents permits the identification of HBV antigens as a red signal and HBV DNA as a blue-purple signal at the single cell level. Both ISH and IHC can be performed in the same tissue section without significantly reducing the sensitivity of either assay. In addition, since this simultaneous detection assay can be completed within two days and eliminates the need for radioactive probes, it may be used effectively as a routine clinical procedure.

DNA Probes↗
PubMed1990

Secretion of neurotoxins by mononuclear phagocytes infected with HIV-1.

Mononuclear phagocytes (microglia, macrophages, and macrophage-like giant cells) are the principal cellular targets for human immunodeficiency virus-1 (HIV-1) in the central nervous system (CNS). Since HIV-1 does not directly infect neurons, the causes for CNS dysfunction in acquired immunodeficiency syndrome (AIDS) remain uncertain. HIV-1-infected human monocytoid cells, but not infected human lymphoid cells, released toxic agents that destroy chick and rat neurons in culture. These neurotoxins were small, heat-stable, protease-resistant molecules that act by way of N-methyl-D-aspartate receptors. Macrophages and microglia infected with HIV-1 may produce neurologic disease through chronic secretion of neurotoxic factors.

Animals↗
PubMed1990

Specific interaction of CD4-bearing liposomes with HIV-infected cells.

The CD4 molecule was reconstituted into the bilayers of large liposomes. Fluorescence microscopy and electron microscopy showed that these liposomes interact with HIV-infected H9-HT cells, delivering their contents to the cell interior. Liposomes bearing CD4 did not interact in this way with noninfected H9-HT cells nor did liposomes without CD4 interact significantly with HIV-infected cells. From electron micrographs, it appeared that HIV binds to liposomes bearing CD4; no attachment of virions to liposomes without CD4 was observed.

CD4 Antigens↗
PubMed1989

In vivo and in vitro ultrastructural alterations induced by human immunodeficiency virus in human lymphoid cells.

The ultrastructural alterations induced by human immunodeficiency virus (HIV) in human lymphoid cells have been evaluated. Electron microscopic examination of peripheral blood mononuclear cells (PBMC) from 14 male homosexuals with confirmed acquired immunodeficiency syndrome (AIDS) or AIDS-related complex revealed that tubuloreticular inclusions were present in 5-15% of the cell sections from each case. In 5 of 14 cases, cylindrical confronting lamellae were found in 1-2% of the cell sections. No retrovirus-like particles or surface membrane alterations were detected. Neither of these structural alterations was observed in control PBMC obtained from six HIV-seronegative, hepatitis B virus surface antigen (HBsAg)-positive carriers or in 11 healthy subjects. When primary cultures of CD4+-enriched lymphocytes were infected in vitro with HIV, tubuloreticular inclusions could be detected in 3-10% of the cell sections, but no cylindrical confronting lamellae-like structures were found. In contrast, neither of these alterations were seen in uninfected or HIV-infected H9-HT continuous cell lines. These in vivo and in vitro studies indicate that there is an association between the appearance of the tubuloreticular inclusions and cytopathic HIV infection, although no correlation between cytopathic changes and active viral replication was observed at the single cell level. Further studies will be required to establish the mechanism(s) of formation of the tubuloreticular inclusions and to determine their prognostic potential.

AIDS-Related Complex↗
PubMed1989

HIV-1-stimulated expression of CD11/CD18 integrins and ICAM-1: a possible mechanism for extravascular dissemination of HIV-1-infected cells.

To identify mechanisms which might facilitate emigration of HIV-1-infected cells from the circulation, we studied the effect of HIV-1 infection on T lymphocyte and monocytoid cell expression of molecules involved in adherence and translocation of leukocytes across endothelial cell barriers. CD11a, CD18, and ICAM-1 were demonstrated on up to 80% of HIV-1-infected H9 T cells by flow cytometry; these molecules were not evident on uninfected H9. CD18 mRNA was detected in HIV-infected, but not in uninfected H9 T cells. Cell surface expression of CD11a and CD18, but not ICAM-1, was increased on HIV-infected, as compared to uninfected U937 and THP1 monocytoid cells. Increased cell surface expression of the leukocyte integrins was associated with a significantly increased tendency of HIV-infected monocytoid cells to adhere to human umbilical vein endothelial cell monolayers or aggregate homotypically. Preincubating the monocytoid cells with anti-CD18 or anti-CD11a or preincubating endothelial cells with anti-ICAM-1 suppressed these cell to cell interactions. These studies suggest that HIV-1 infection stimulates cell surface expression of molecules involved in leukocyte adherence and transendothelial migration in vitro. Similar mechanisms may influence leukocyte trafficking, in vivo, and may play a role in the localization of HIV-1 infected cells in the central nervous system and other tissues.

Antigens, Differentiation↗
PubMed1987

Bowen's disease of the feet. Presence of human papillomavirus 16 DNA in tumor tissue.

A 36-year-old black man with bilateral squamous cell carcinoma in situ of the feet is described. The DNA hybridization analysis performed on the tumor tissue demonstrated the presence of human papillomavirus 16 DNA. Human papillomavirus 16 has been detected repeatedly in genital carcinomas, and evidence is mounting that it may play an important role in the development of malignancy.

Adult↗
PubMed1987

Fusion as a mediator of cytolysis in mixtures of uninfected CD4+ lymphocytes and cells infected by human immunodeficiency virus.

We describe an unusual type of cytopathology in which uninfected CD4+ (helper/inducer) cells (cells expressing the human leukocyte antigen CD4) interact with cells persistently infected with the human immunodeficiency virus (HIV). Prior antigenic stimulation was not required, since CD4+ cells taken either from healthy persons without anti-HIV antibodies or from individuals with anti-HIV antibodies were capable of inducing cytolysis. Neither CD8+ (suppressor/cytotoxic) nor CD16+ (natural killer) cells mediated the reaction. Light microscopic and autoradiographic studies revealed that, prior to cytolysis, multinucleated giant cells were formed from fusions between HIV-infected cells and large numbers of uninfected CD4+ lymphocytes. These data may explain the paradox that exists in vivo in which a dramatic depletion of CD4+ lymphocytes occurs in the presence of a small number of HIV-infected CD4+ cells. These new insights into the pathogenesis of acquired immunodeficiency syndrome (AIDS) may lead to future therapeutic strategies.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Extrachromosomal sequences of hepatitis B virus DNA in peripheral blood mononuclear cells of acquired immune deficiency syndrome patients.

The primary etiologic agent of the acquired immune deficiency syndrome (AIDS) is a human T-lymphotropic retrovirus (the AIDS virus). However, the pathogenesis of this virus suggests that other cofactors may contribute to the development of clinically overt disease. The hepatitis B virus (HBV) has been implicated as a potential cofactor because HBV and AIDS virus infections frequently coexist, striking similarities exist in their epidemiologic patterns, and recent data indicate that HBV is lymphotropic. To establish the prevalence of HBV infections in lymphoid cells from individuals with AIDS-related disorders, sera and peripheral blood mononuclear cells (PBMC) from 16 males with AIDS virus infections were examined for the presence of HBV DNA by DNA X DNA blot hybridization. Fifteen (94%) of these individuals had serologic evidence of a recent or prior HBV infection. HBV DNA was detected in the PBMC of all of these patients, regardless of existing HBV serology. Among the 36 control individuals without AIDS-related symptomatology, PBMC-associated HBV DNA was detected in 8 of 14 carriers of hepatitis B surface antigen (HBsAg) and in 3 of 10 individuals immune to HBV, but it was absent from the PBMC of 12 individuals without HBV infection. In all instances, the HBV DNA was extrachromosomal and existed as replicative intermediates or high molecular weight oligomers of the viral genome. Replicative intermediates and serum-associated HBV DNA were detected in all hepatitis B e antigen-positive carriers, regardless of their clinical status. In contrast, the high molecular weight oligomers of HBV DNA were detected in the PBMC of all of the AIDS virus-infected patients examined, but in only 33% of those in the control group who had evidence of HBV infection. This finding suggests that a unique and complex HBV-host-cell interaction exists in patients infected with the AIDS virus.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Hepatitis B virus DNA in mononuclear cells and analysis of cell subsets for the presence of replicative intermediates of viral DNA.

To determine whether peripheral blood mononuclear cells (PBMCs) contain replicating forms of hepatitis B virus (HBV) DNA and to define which cell subset may be permissive for viral replication, we analyzed the PBMC DNA from 14 carriers positive for hepatitis B surface antigen (HBsAg) by Southern blot hybridization. HBV-related DNA, which was present exclusively in an extrachromosomal state, was found in the PBMCs of all five hepatitis B e antigen (HBeAg)-positive and three of nine HBeAg-negative carriers. Serum-associated HBV DNA was detected only in those HBsAg carriers whose PBMCs contained HBV DNA forms resembling replicative intermediates (1.0-3.2 kilobase pairs in the EcoRI digests). Analysis of PBMC subsets revealed that replicating forms of the HBV genome were present primarily in monocytes. Low levels of hybridization also were detected in B cells, whereas the T cell fraction (which contained natural killer cells) appeared to be devoid of these replicating forms.

DNA Replication↗
PubMed1978

Temperature-sensitive mutants of simian virus 40. I. Isolation aand preliminary characterization of B/C gene mutants.

Sixteen temperature-sensitive mutants of simian virus 40 were isolated after treatment of wild-type virus with UV light, nitrous acid, or nitrosoguanidine. All of the mutants were assigned to the B complementation group on the basis of quantitative complementation analyses. Characterization of several representative mutants revealed that under restrictive conditions such mutants produced immunologically identifiable tumor and viral capsid antigens, induced the synthesis of cellular DNA, and replicated infectious viral DNA. In addition, mutant particles produced at 33 degrees were more heat-labile than wild-type virus. This collection of mutants will be useful in an analysis of SV40 particle morphogenesis.

Animals↗
PubMed1978

Transformation by viruses: simian virus 40 as a model system.

Simian virus 40 (SV40), a DNA-containing tumor virus in the papovavirus group, represents an ideal model system for the analysis of the mechanism of viral-induced tumorigenesis because of the small size of its genome and its broad range of oncogenic potential. Viral genes persist and are expressed in SV40-transformed cells. Temperature-sensitive (ts) mutants of the virus have proved to be valuable tools for the identification and analysis of viral gene expression in transformed cells. Through the use of such mutants, it has been determined that a specific gene product (A-protein) is required to initiate cellular transformation. The role of virus genes in the maintenance of the transformed state was determined by transformation of the cells of mouse, hamster, and human origin by ts virus containing A-gene mutations. These cells were then examined under permissive and nonpermissive conditions for the presence of a variety of intracellular and surface alterations commonly associated with neoplastic transformation. From the results of such experiments, it has been concluded that an SV40-specific function is also necessary for the maintenance of at least some of the phenotypic properties of the transformed state. Indirect evidence, derived from a comparison of the biological and biochemical properties of the SV40-induced tumor (T) antigen and the gene A-protein, supports the idea that T-antigen is a product of the A-gene. One model devised to explain the mechanism by which the gene A-protein might function as an effector of transformation is presented.

Animals↗