Biomedical subjects

E O Major

Publications and source records attributed to E O Major.

At least 37 records · Page 2Linked to original sources

PubMed1999

JC virus DNA is present in the mucosa of the human colon and in colorectal cancers.

JC virus (JCV) is a polyoma virus that commonly infects humans. We have found T antigen DNA sequences of JCV in the mucosa of normal human colons, colorectal cancers, colorectal cancer xenografts raised in nude mice, and in the human colon cancer cell line SW480. A larger number of viral copies is present in cancer cells than in non-neoplastic colon cells, and sequence microheterogeneity occurs within individual colonic mucosal specimens. The improved yield of detection after treatment with topoisomerase I suggests that the viral DNA is negatively supercoiled in the human tissues. These results indicate that JCV DNA can be found in colonic tissues, which raises the possibility that this virus may play a role in the chromosomal instability observed in colorectal carcinogenesis.

Animals↗

PubMed1999

Transient exposure to HIV-1 Tat protein results in cytokine production in macrophages and astrocytes. A hit and run phenomenon.

The pathological correlates of dementia due to human immunodeficiency virus (HIV) infection are glial cell activation and cytokine dysregulation. These findings occur in the setting of small numbers of productively infected cells within the brain. We determined whether exposure of susceptible cells to Tat protein of HIV could result in the production of select proinflammatory cytokines. In a dose-responsive manner, Tat induced interleukin (IL)-1beta production in monocytic cells, while astrocytic cells showed an increase in mRNA for IL-1beta, but had a translation block for IL-1beta protein production. Conversely, IL-6 protein and mRNA productions were strongly induced in astrocytic cells and minimally in monocytic cells. IL-1beta and IL-6 production were independent of tumor necrosis factor-alpha production. An exposure to Tat for a few minutes was sufficient for sustained releases of cytokines for several hours. This prolonged cytokine production is likely maintained by a positive feed back loop of Tat-induced nuclear factor kappaB activation and cytokine production that is independent of extracellular calcium. Thus a transient exposure may be sufficient to initiate a cascade of events resulting in cerebral dysfunction and a "hit and run" approach may be in effect. Hence cross-sectional measurement of viral load in the brain may not be a useful indicator of the role of viral products in the neuropathogenesis of HIV dementia.

Astrocytes↗

PubMed1999

Relation of JC virus DNA in the cerebrospinal fluid to survival in acquired immunodeficiency syndrome patients with biopsy-proven progressive multifocal leukoencephalopathy.

The detection and semiquantitation of JC virus (JCV) DNA in cerebrospinal fluid (CSF) is prognostic of survival and is a marker of the course of progressive multifocal leukoencephalopathy (PML). CSF samples from 15 acquired immunodeficiency syndrome (AIDS) patients with biopsy-proven PML were analyzed by semiquantitative polymerase chain reaction (PCR). A low JCV burden was predictive of longer survival compared with a high JCV burden (median survival from entry, 24 [2-63] vs 7.6 [4-17] weeks). Further analyses indicated a possible threshold of 50 to 100 copies/microl separating high- and moderate-risk cases. Patients with a JCV load below this level survived longer than those with a JCV load above it.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Viral variant nucleotide sequences help expose leukocytic positioning in the JC virus pathway to the CNS.

The human polyomavirus JCV lytically infects oligodendrocytes of immunosuppressed individuals leading to the fatal demyelinating disease termed progressive multifocal leukoencephalopathy (PML). Dementia, hemiparesis, and hemianopsia are the predominant presenting signs of PML. Asymptomatic JCV infection is common worldwide with approximately 80% of adults testing positive for JCV antibodies. In addition to the brain, JCV has been shown to infect tonsil, lymphoid, bone marrow, and kidney tissues. Viral variants, classified according to the nucleotide sequences of their regulatory regions, are being mapped in human tissues and cell types to help trace the pathway of JCV from a site of initial infection to target oligodendrocytes. In most literature, a dichotomy of the JCV regulatory region structure exists by tissue. B lymphocytes, however, have demonstrated the capacity to harbor JCV of diverse regulatory regions, which helps position their interaction with virus amid every stage of infection and implicates a lymphocytic role in latency.

Animals↗

PubMed1999

Progressive multifocal leukoencephalopathy.

Before the AIDS epidemic, progressive multifocal leukoencephalopathy (PML) was a rare disorder occurring most often in association with leukemia and lymphoma. Current estimates indicate that PML ultimately develops in up to 5% of all patients with AIDS. This demyelinating disease results from infection with JC virus, a papova virus, that most of the world's population is exposed to prior to adulthood. Although PML commonly occurs in the setting of advanced immunosuppression, it may be observed in patients with CD4 lymphocyte counts in excess of 200 cells/mm3. Focal neurological symptoms and signs coupled with hyperintense signals abnormalities of the white matter on T2-weighted cranial magnetic resonance imaging are highly suggestive of the disease. In this setting, a positive CSF polymerase chain reaction for JCV DNA has been felt to be sufficiently diagnostic to eliminate the need for brain biopsy. Survival of AIDS-associated PML is poor with median survivals averaging just 6 months. However, as many as 10% of AIDS patients with PML will have prolonged (>12 months) survival and partial recovery. Highly active antiretroviral therapy (HAART) has been demonstrated to have a salutary effect on survival.

Humans↗

PubMed1998

The JC and BK human polyoma viruses appear to be recent introductions to some South American Indian tribes: there is no serological evidence of cross-reactivity with the simian polyoma virus SV40.

In an effort to understand the unusual cytogenetic damage earlier encountered in the Yanomama Indians, plasma samples from 425 Amerindians representing 14 tribes have been tested for hemagglutination inhibition antibodies to the human JC polyoma virus and from 369 Amerinds from 13 tribes for hemagglutination inhibition antibodies to the human BK polyoma virus. There is for both viruses highly significant heterogeneity between tribes for the prevalence of serum antibody titers >/=1/40, the pattern of infection suggesting that these two viruses only relatively recently have been introduced into some of these tribes. Some of these samples, from populations with no known exposure to the simian polyoma virus SV40, also were tested for antibodies to this virus by using an immunospot assay. In contrast to the findings of Brown et al. (Brown, P., Tsai, T. & Gajdusek, D. C. (1975) Am. J. Epidemiol. 102, 331-340), none of the samples was found to possess antibodies to SV40. In addition, no significant titers to SV40 were found in a sample of 97 Japanese adults, many of whom had been found to exhibit elevated titers to the JC and BK viruses. This study thus suggests that these human sera contain significant antibody titers to the human polyoma viruses JC and BK but do not appear to contain either cross-reactive antibodies to SV40 or primary antibodies resulting from SV40 infection.

Adult↗

PubMed1998

IFN-gamma inhibits AP-1 binding activity in human brain-derived cells through a nitric oxide dependent mechanism.

It has been demonstrated that CNS levels of the cytokine IFN-gamma are elevated in association with a number of neuro-inflammatory diseases. In the present study, we have examined the effect of this cytokine on human brain derived cells. We show that prolonged treatment (22 h) of such cells with IFN-gamma inhibits the DNA binding activity of transcription factor AP-1. Furthermore, we show that this effect can be reversed by either N(G)-monomethyl-L-arginine (L-NMMA) or L-N5-(1-iminoethyl)ornithine (L-NIO), competitive inhibitors of nitric oxide synthase activity [Rees et al., 1990]. In addition, we show that treatment of brain-derived cells with the nitric oxide donor 3-morpholinosydnonimine, HCl (SIN-1), or [N-(b-D-glucopyranosyl)-N2-acetyl-S-nitroso-D,L-penicillaminamide] (glyco-SNAP-1), also inhibits the binding activity of AP-1. Together, these results suggest that IFN-gamma can inhibit AP-1 binding activity through a nitric oxide dependent mechanism.

Brain↗

PubMed1998

Induction of monocyte chemoattractant protein-1 in HIV-1 Tat-stimulated astrocytes and elevation in AIDS dementia.

Activated monocytes release a number of substances, including inflammatory cytokines and eicosanoids, that are highly toxic to cells of the central nervous system. Because monocytic infiltration of the central nervous system closely correlates with HIV-1-associated dementia, it has been suggested that monocyte-derived toxins mediate nervous system damage. In the present study, we show that the HIV-1 transactivator protein Tat significantly increases astrocytic expression and release of monocyte chemoattractant protein-1 (MCP-1). Astrocytic release of beta-chemokines, which are relatively less selective for monocytes, including RANTES, macrophage inflammatory protein-1alpha, and macrophage inflammatory protein-1beta, was not observed. We also show that MCP-1 is expressed in the brains of patients with HIV-1-associated dementia and that, of the beta-chemokines tested, only MCP-1 could be detected in the cerebrospinal fluid of patients with this condition. Together, these data provide a potential link between the presence of HIV-1 in the brain and the monocytic infiltration that may substantially contribute to dementia.

AIDS Dementia Complex↗

PubMed1998

Detection of JC virus DNA in human tonsil tissue: evidence for site of initial viral infection.

Progressive multifocal leukoencephalopathy is a demyelinating disease of the human central nervous system that results from lytic infection of oligodendrocytes by the polyomavirus JC (JCV). Originally, JCV was thought to replicate exclusively in human glial cells, specifically oligodendrocytes. However, we have recently shown that JCV can replicate in cells of lymphoid origin such as hematopoietic precursor cells, B lymphocytes, and tonsillar stromal cells. To determine whether tonsils harbor JCV, we tested a total of 54 tonsils, 38 from children and 16 from adult donors. Nested PCRs with primer sets specific for the viral T protein and regulatory regions were used for the detection of JCV DNA. JCV DNA was detected in 21 of 54 tonsil tissues, or 39% (15 of 38 children and 6 of 16 adults) by using regulatory-region primers and in 19 of 54 tonsil tissues, or 35% (13 of 38 children and 6 of 16 adults) by using the T-protein primers. The DNA extracted from children's nondissected tonsil tissue, isolated tonsillar lymphocytes, and isolated stromal cells that demonstrated PCR amplification of the JCV regulatory region underwent cloning and nucleotide sequencing. Of the regulatory-region sequences obtained, nearly all contained tandem repeat arrangements. Clones originating from nondissected tonsil tissue and tonsillar lymphocytes were found to have sequences predominantly of the Mad-1 prototype strain, whereas the majority of clones from the DNA of tonsillar stromal cells had sequences characteristic of the Mad-8br strain of JCV. A few clones demonstrated structures other than tandem repeats but were isolated only from tonsillar lymphocytes. These data provide the first evidence of the JCV genome in tonsil tissue and suggest that tonsils may serve as an initial site of viral infection.

Adolescent↗

PubMed1998

The efficacy of nucleoside analogs against JC virus multiplication in a persistently infected human fetal brain cell line.

The effectiveness of nucleoside analogs in blocking viral multiplication was evaluated using an immortalized human neuroglial cell line capable of sustaining a persistent JCV infection, SVG-JC. Results from in situ DNA hybridization and hemagglutination assays performed on drug treated cultures were used as a measure of viral DNA replication and multiplication, respectively. Of the three drugs tested, Ara-C (cytosine arabinoside), AZT (3'-azido-3'-deoxythymidine), and cidofovir (S)-1-[3-hydroxy-2-(phosphonylmethoxypropyl] cytosine), only Ara-C showed a significant effect in decreasing active JCV replication and multiplication. In vitro data, using different cell types and virus strains have shown that specific drugs can indeed modulate viral infection. However, such modulation has not previously been demonstrated in those cells of the CNS which are specifically targeted by JCV. The SVG-JC cells represent a unique system with which further studies can be conducted on the effects of drugs on brain derived cells that are susceptible to viral infection.

Anti-HIV Agents↗

PubMed1998

JC virus infection in cells from lymphoid tissue.

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease characterized by infection of oligodendrocytes by JC virus. The exact nature of the pathogenesis of PML is not known. The nature of the primary infection, the site of viral latency, and the route by which JCV enters the brain remain to be elucidated. Different laboratories have shown the presence of JCV in peripheral lymphocytes from immunosuppressed individuals, suggesting these cells as possible carriers of JCV to the brain. To examine this observation, we tested the susceptibility to JCV infection of cells from lymphoid organs, focusing our attention on CD34+ haematopoietic precursor cells and B lymphocytes. The results demonstrate that both these cell types are susceptible to JCV infection and, moreover, that JCV can infect only those cells that differentiate into lymphocytic lineage.

Antigens, CD34↗

PubMed1997

Different kynurenine pathway enzymes limit quinolinic acid formation by various human cell types.

Substantial increases in the tryptophan-kynurenine pathway metabolites, l-kynurenine and the neurotoxin quinolinic acid, occur in human brain, blood and systemic tissues during immune activation. Studies in vitro have shown that not all human cells are capable of synthesizing quinolinate. To investigate further the mechanisms that limit l-kynurenine and quinolinate production, the activities of kynurenine pathway enzymes and the ability of different human cells to convert pathway intermediates into quinolinate were compared. Stimulation with interferon gamma substantially increased indoleamine 2,3-dioxygenase activity and L-kynurenine production in primary peripheral blood macrophages and fetal brains (astrocytes and neurons), as well as cell lines derived from macrophage/monocytes (THP-1), U373MG astrocytoma, SKHEP1 liver and lung (MRC-9). High activities of kynurenine 3-hydroxylase, kynureninase or 3-hydroxyanthranilate 3,4-dioxygenase were found in interferon-gamma-stimulated macrophages, THP-1 cells and SKHEP1 cells, and these cells made large amounts of quinolinate when supplied with L-tryptophan, L-kynurenine, 3-hydroxykynurenine or 3-hydroxyanthranilate. Quinolinate production by human fetal brain cultures and U373MG cells was restricted by the low activities of kynurenine 3-hydroxylase, kynureninase and 3-hydroxyanthranilate 3,4-dioxygenase, and only small amounts of quinolinate were synthesized when cultures were supplied with L-tryptophan or 3-hydroxyanthranilate. In MRC-9 cells, quinolinate was produced only from 3-hydroxykynurenine and 3-hydroxyanthranilate, consistent with their low kynurenine 3-hydroxylase activity. The results are consistent with the notion that indoleamine 2,3-dioxygenase is an important regulatory enzyme in the production of L-kynurenine and quinolinate. Kynurenine 3-hydroxylase and, in some cells, kynureninase and 3-hydroxyanthranilate 3,4-dioxygenase are important determinants of whether a cell can make quinolinate.

Astrocytoma↗

PubMed1997

Propagation of the human polyomavirus, JCV, in human neuroblastoma cell lines.

Susceptibility to infection by the human polyomavirus, JCV, is determined by intracellular mechanisms which control transcription and replication. Originally thought to propagate well only in human cells of oligodendroglial lineage, JCV has recently been shown to infect astrocytes, astrogliomas, and a neuroblastoma cell line. The data reported here describe two cell types that have been subcultured from a human neuroblastoma cell line, SK-N-SH. The SH-SY5Y subclone displays neuronal phenotypes and is not susceptible to JCV infection, while the SH-EP subclone displays glial cell phenotypes and is susceptible to infection. Binding of nuclear proteins from the permissive SH-EP cells to the nuclear factor-1 (NF-1) site in the JCV regulatory DNA sequences results in a gel shift pattern that is different from the nonpermissive SH-SY5Y cell proteins. Northern analysis of mRNA for the four classes of NF-1 proteins showed a predominance of the NF-1/X class in SH-EP cells similar to the highly permissive human fetal glial cells. Very low levels of mRNA for NF-1/X were seen in the nonpermissive SH-SY5Y cells, similar to that seen for the nonpermissive HeLa cells. Several other cell lines tested that were permissive for JCV infection also showed synthesis of the NF-1/X class of proteins. SH-EP cells represent a cell line in a glial cell lineage which is susceptible to JCV multiplication. These cells may be a useful cell culture system for the investigation of DNA binding factors which correlates with viral susceptibility.

Antigens, Viral↗

PubMed1997

Review: JC virus infection of lymphocytes--revisited.

JC virus (JCV), the causative agent of the fatal human demyelinating disease progressive multifocal leukoencephalopathy (PML), is an opportunistic papovavirus that infects and destroys oligodendrocytes, the myelin-producing cells of the central nervous system. Since its isolation from the brain of a PML patient, JCV has long been classed as a neurotropic virus. Many studies, however, have demonstrated that JCV can infect various other cell types, including immune system cells. Moreover, several recent studies have focused specifically on lymphocytes as a target of JCV. This review chronicles the association of JCV with lymphocytes, including cell type localization, molecular regulation, and viral sequences, and discusses clinical implications of these findings.

Antigens, Viral↗

PubMed1997

Progressive multifocal leukoencephalopathy: molecular biology, pathogenesis and clinical impact.

The human polyomaviruses JC virus (JCV) and BK virus (BKV) have long been known as onco- and neurooncogenic. Interest in their oncogenic potential has reemerged with the discovery of simian virus 40 DNA in human brain tumors including the pituitary as well as in bone tumors and mesotheliomas. The only human disease caused by an infection with the human polyomavirus JCV is progressive multifocal leukoencephalopathy (PML) characterized by a lytic infection of oligodendrocytes with consecutive demyelination. Malignant transformation of cell lines appears to be caused by a complex interaction of the viral large T (tumor) antigen with several transcription factors and tumor suppressor proteins such as p53 and the retinoblastoma protein. PML, once an extremely rare disease, has become much more frequent in the western world owing to the AIDS pandemic. An exceedingly complicated, cell-, tissue- and species-specific pattern of protein-DNA interaction and negative as well as positive feedback regulation by at least a dozen proteins and possibly mutations in the JC viral promoter-enhancer region govern host range and development of PML. The intricate molecular and immunological prerequisites ultimately leading to PML in humans have not yet been completely elucidated.

Animals↗

PubMed1996

High titers of antibodies to two human polyomaviruses, JCV and BKV, correlate with increased frequency of chromosomal damage in human lymphocytes.

Associations of antibody titers to the JC and BK human polyoma viruses and the frequency of chromosome aberrations (CA) in human peripheral blood lymphocytes were studied. Study group consisted of 33 workers occupationally exposed to low doses of ionizing radiation and 11 control persons. There were no statistically significant differences in the JC and BK virus titer values between two groups of donors. It was found that JC and BK virus titers explained approximately 6% of total inter-individual variation in CA frequency. Such factors as alcohol abuse, age and, in this special group, exposure to ionizing radiation explained an additional 53% of the total variation in CA frequency. In six clean-up workers and one control, rogue cell (cells with multiple chromosome-type aberrations) were found. The incidence of rogue cells correlated significantly with JC and BK virus titers as well as a history of recent acute respiratory disease.

Adult↗

PubMed1996

Human microglia convert l-tryptophan into the neurotoxin quinolinic acid.

Immune activation leads to accumulations of the neurotoxin and kynurenine pathway metabolite quinolinic acid within the central nervous system of human patients. Whereas macrophages can convert L-tryptophan to quinolinic acid, it is not known whether human brain microglia can synthesize quinolinic acid. Human microglia, peripheral blood macrophages and cultures of human fetal brain cells (astrocytes and neurons) were incubated with [13C6]L-tryptophan in the absence or presence of interferon gamma. [13C6]Quinolinic acid was identified and quantified by gas chromatography and electron-capture negative-chemical ionization mass spectrometry. Both L-kynurenine and [13C6]quinolinic acid were produced by unstimulated cultures of microglia and macrophages. Interferon gamma, an inducer of indoleamine 2,3-dioxygenase, increased the accumulation of L-kynurenine by all three cell types (to more than 40 microM). Whereas large quantities of [13C6]quinolinic acid were produced by microglia and macrophages (to 438 and 1410 nM respectively), minute quantities of [13C6]quinolinic acid were produced in human fetal brain cultures (not more than 2 nM). Activated microglia and macrophage infiltrates into the brain might be an important source of accelerated conversion of L-tryptophan into quinolinic acid within the central nervous system in inflammatory diseases.

Astrocytes↗

PubMed1996

Hypothesis: "Rogue cell"-type chromosomal damage in lymphocytes is associated with infection with the JC human polyoma virus and has implications for oncopenesis.

The hemagglutination inhibition antibody titers against the JC and BK polyoma viruses (JCV and BKV, respectively) are significantly elevated in individuals exhibiting "rogue" cells among their cultured lymphocytes. However, the elevation is so much greater with respect to JCV that the BKV elevation could readily be explained by cross reactivity to the capsid protein of these two closely related viruses. The JCV exhibits high sequence homology with the simian papovavirus, simian virus 40 (SV40), and inoculation of human fetal brain cells with JCV produces polyploidy and chromosomal damage very similar to that produced by SV40. We suggest, by analogy with the effects of SV40, that these changes are due to the action of the viral large tumor antigen, a pluripotent DNA binding protein that acts in both transcription and replication. The implications of these findings for oncogenesis are briefly discussed.

Adolescent↗