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Biomedical subjects

E O Major

Publications and source records attributed to E O Major.

At least 55 records · Page 3Linked to original sources
PubMed1996

Recombinant human interleukin 1 beta induces production of prostaglandins in primary human fetal astrocytes and immortalized human fetal astrocyte cultures.

Astrocytes play an important role in initiating and modulating inflammatory responses within the central nervous system. Extensive studies in rodents have shown that TPA, substance P, calcium ionophore A21387, and lipopolysaccharide (LPS) induce formation and release of arachidonic acid metabolites which have immunoregulatory properties. To better understand the immunopathology of brain injury, we studied the role of inflammatory cytokines such as tumor necrosis factor alpha, interleukin (IL) 6, IL-2, interferon gamma and IL-1 beta in the production of arachidonic acid metabolites in cells from fetal human brain. Among these cytokines, only IL-1 beta significantly stimulated production of prostaglandins E2 and F2 alpha but not PGD2, thromboxane B2 and 6-keto-PGF1 alpha. Under our experimental conditions, these astrocyte cultures did not produce metabolites in the lipoxygenase pathway such as leukotrienes B4 and C4 upon IL-1 beta stimulation. The stimulatory effects of IL-1 beta on the induction of arachidonic acid metabolites have been studied in various human cell types but not in astrocytes. Human astrocyte production of PGF2 alpha and PGE2 but not PGD2, 6-keto-PGF1 alpha and TXB2 when stimulated by IL-1 beta, is thus a novel finding. This observation should initiate investigations into the mechanism of arachidonic acid metabolism and the role of its metabolites in inflammation in the human nervous system.

Arachidonic Acid↗
PubMed1996

JC virus infection of hematopoietic progenitor cells, primary B lymphocytes, and tonsillar stromal cells: implications for viral latency.

The human polyomavirus JC virus (JCV) infects myelin-producing cells in the central nervous system, resulting in the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). JCV-induced PML occurs most frequently in immunosuppressed individuals, with the highest incidence in human immunodeficiency type 1-infected patients, ranging between 4 and 6% of all AIDS cases. Although JCV targets a highly specialized cell in the central nervous system, infection is widespread, with more than 80% of the human population worldwide demonstrating serum antibodies. A number of clinical and laboratory studies have now linked the pathogenesis of PML with JCV infection in lymphoid cells. For example, JCV-infected lymphocytes have been suggested as possible carriers of virus to the brain following reactivation of a latent infection in lymphoid tissues. To further define the cellular tropism associated with JCV, we have attempted to infect immune system cells, including CD34+ hematopoietic progenitor cells derived from human fetal liver, primary human B lymphocytes, and human tonsillar stromal cells. Our results demonstrate that these cell types as well as a CD34+ human cell line, KG-1a, are susceptible to JCV infection. JCV cannot, however, infect KG-1, a CD34+ cell line which differentiates into a macrophage-like cell when treated with phorbol esters. In addition, peripheral blood B lymphocytes isolated by flow cytometry from a PML patient demonstrate JCV infection. These results provide direct evidence that JCV is not strictly neurotropic but can infect CD34+ hematopoietic progenitor cells and those cells which have differentiated into a lymphocytic, but not monocytic, lineage.

B-Lymphocytes↗
PubMed1996

Extracellular human immunodeficiency virus type 1 Tat protein is associated with an increase in both NF-kappa B binding and protein kinase C activity in primary human astrocytes.

Human immunodeficiency virus type 1 (HIV-1) infection has been associated with an increase in the binding of the transcription factor NF-kappa B to its consensus sequence in the viral promoter. Using cultures of primary human fetal astrocytes, we show that exogenous HIV-1 Tat protein, which has been demonstrated to be released from infected cells, is associated with an increase in the binding of this transcription factor to an HIV-1 long terminal repeat kappa B sequence. This effect occurs rapidly and is independent of new protein synthesis. We also demonstrate that extracellular Tat protein is associated with an increase in protein kinase C activity. If Tat functions similarly in other cell types, such findings could relate to some of this protein's previously described physiological effects. These effects include Tat's ability to upregulate the synthesis of specific cytokines and to act as a growth factor.

Antibodies, Viral↗
PubMed1996

Expression of multiple classes of the nuclear factor-1 family in the developing human brain: differential expression of two classes of NF-1 genes.

Nuclear factor-1 (NF-1) is a multifunctional protein that participates in both transcription and replication. NF-1 proteins exist as a family of proteins that share some common structural and functional features but also demonstrate organ and cell type specific expression. Based upon these characteristics, the family of NF-1 proteins is divided into four classes, A, B, C and D. Several NF-1 binding sites have been identified in the regulatory sequences of the human polyomavirus, JCV, which multiplies most efficiently in glial cells derived from human fetal brain. Nuclear proteins from these cultures bind specifically to these NF-1 sites. It is not known, however, which member(s) of the NF-1 family is expressed in cells susceptible to JCV infection. We have examined glial cells as well as HeLa cells, which are not permissive to JCV, for NF-1 expression. By RT-PCR analysis, all four classes of NF-1 are expressed in human fetal glial cells and HeLa cells. However, by Northern analysis the expression of class D gene is much higher in the glial cells than HeLa cells. Expression of the class C gene, first identified in HeLa cells as NF-1/CTF1, is barely detectable in glial cells but highly expressed in HeLa cells. The screening of cDNA libraries from two early human brain tissues resulted in the identification of a number of clones which appear to be related and belong to a single class of the NF-1 family, class D. Nucleotide sequence of one clone, designated NF-1/AT1, confirms this. The NF-1/AT1 protein was overexpressed in E coli and found to bind specifically to an NF-1 probe by gel shift analysis. Southern analysis of human fetal glial cells indicates that the NF-1/AT1 gene, class D, is derived from a different gene than NF-1/CTF1. These results suggest the possibility that genes or viruses, like JCV, which use NF-1 for their expression in human brain derived cells may preferentially use the NF-1 class D protein.

Amino Acid Sequence↗
PubMed1995

Evaluation of the role of cytokine activation in the multiplication of JC virus (JCV) in human fetal glial cells.

The human polyomavirus, JCV, is the etiologic agent of the fatal central nervous system demyelinating disease, progressive multifocal leukoencephalopathy. Progressive multifocal leukoencephalopathy occurs most frequently in patients with underlying immunosuppressive disorders and is the direct result of virus multiplication in oligodendrocytes, the myelin producing cell in the central nervous system. In this report we test the ability of cellular activation signals to modulate expression of the JCV genome in either transfected or infected human fetal glial cells. In addition, we analyze the binding of nuclear proteins isolated from untreated and cytokine treated human fetal glial cells to transcription factor binding sites in the JCV regulatory region. In contrast to the effects of cellular activation on the expression of the HIV-1 promoter in these cells, none of the cellular activators tested increased expression of JCV. The cytokine, TNF-alpha, increased binding of NF kappa B (p50/p65) to a JC NF kappa B site but did not modulate the binding of nuclear proteins to the overlapping NF-1/AP1 region of the JCV enhancer. When taken together these results suggest that the response of JCV to cellular activation signals may be fundamentally different from the response of HIV-1 to these signals in human fetal glial cells and that the JC NF kappa B site may not be required for JCV gene expression or multiplication in vivo.

Antibody Specificity↗
PubMed1995

Progressive multifocal leukoencephalopathy: clinical and laboratory observations on a viral induced demyelinating disease in the immunodeficient patient.

Progressive multifocal leukoencephalopathy is a viral-induced demyelinating disease of the central nervous system usually occurring in the immunocompromised individual. The incidence of progressive multifocal leukoencephalopathy has risen sharply over the past decade because of widespread human immunodeficiency virus infection leading to immunodeficiency. This increased incidence of progressive multifocal leukoencephalopathy may also be due to better recognition of its clinical signs, and more rapid and reliable laboratory diagnosis of JC virus, the etiologic agent. There have also been advances in the molecular detection of the JC virus and the identification of variations in the viral genome sequence that may affect its multiplication cycle in different tissues. Clinical and basic research have resulted in a better understanding of the pathogenesis of progressive multifocal leukoencephalopathy and have provided sufficient information to plan new approaches for treatment.

AIDS-Related Opportunistic Infections↗
PubMed1994

Progressive multifocal leukoencephalopathy complicating Wiskott-Aldrich syndrome. Report of a case and review of the literature of progressive multifocal leukoencephalopathy with other inherited immunodeficiency states.

OBJECTIVE: To describe the occurrence of progressive multifocal leukoencephalopathy (PML) in association with Wiskott-Aldrich syndrome, an X-linked recessive disorder with impairment of both cellular and humoral immunity. DESIGN: A detailed analysis of this patient's clinical illness, immunologic factors, neuroradiographic findings, and brain histopathologic conditions was undertaken. The medical literature on PML complicating congenital immunodeficient states was also reviewed. SETTING: A 1500-bed, university-affiliated, public health hospital. PATIENT: A 15-year-old boy with Wiskott-Aldrich syndrome. His neurologic illness was heralded by dysarthria and right-sided weakness and the diagnosis was established by brain biopsy specimen. Survival from the time of onset of PML was 10 months. CONCLUSION: Although PML typically occurs in the setting of severe acquired cellular immunodeficiency, often as a consequence of acquired immunodeficiency syndrome, organ transplantation, and leukemia and lymphoma, it may rarely accompany inherited immunodeficiency syndromes. The reported childhood cases of PML include three patients, aged 5, 11, and 18 years, with other inherited immunodeficiency syndromes. This patient represents the first time (to our knowledge) that PML has been reported to occur in association with Wiskott-Aldrich syndrome.

Adolescent↗
PubMed1994

Overexpression and reactivation of binding activity of the recombinant CTF/NF-1 transcription factor.

The transcription factor CTF/NF-1 is a multifunctional cellular protein which participates in the expression of host and viral genes and in the replication of viral DNA. A procedure was developed to obtain recombinant CTF/NF-1 protein in order to help identify the binding sites of CTF/NF-1 protein in the regulatory region of viral sequences. Cloning and expression of the CTF/NF-1 gene downstream from a T7 RNA polymerase promoter resulted in an insoluble protein produced in Escherichia coli. Specific binding by the recombinant CTF/NF-1 protein to its cognate recognition site was obtained only after a denaturation and renaturation procedure. No special chromatography steps were required to obtain a rCTF/NF-1 preparation which could be used for our binding studies. Specific binding was detected with an NF-1 oligonucleotide and with viral DNA templates. Binding to the viral DNA sequences was identical to that previously published with biochemically purified cellular CTF/NF-1 protein.

Adenoviruses, Human↗
PubMed1994

Down-regulation of glial fibrillary acidic protein expression during acute lytic varicella-zoster virus infection of cultured human astrocytes.

The effects of the varicella-zoster virus (VZV) OKA vaccine strain in producing morphologic and antigenic changes in dissociated cultures of human fetal brain was investigated. Cultures containing 80% glial acidic fibrillary protein (GFAP), GFAP+ (positive) astrocytes and 20% GFAP- (negative) fibroblastic-like cells were infected with cell-free VZV OKA at a multiplicity of infection of 0.1 plaque-forming units per cell. Cytopathic effects and significant viral antigen labeling with antibodies against VZV gpl and immediate-early (IE) protein 62 were first detected 6 to 7 days postinfection. Several observations indicated that astrocyte GFAP expression was altered and diminished as a result of VZV infection itself, thereby raising doubts about the utility of combining cell markers and viral antigenic labeling in assessing the susceptibility of neural cell types to viral infection. The down-regulation of GFAP expression by VZV appears to be mediated by early rather than late events in the viral replication cycle and may not be the result of virally induced global shut-off of host cell protein synthesis. Similar observations were made using VZV Ellen, a multipassaged, nonvaccine strain. These observations have potential in vivo implications related to histologic analysis of VZV-infected tissues and disease pathogenesis.

Astrocytes↗
PubMed1994

An increase in p50/p65 NF-kB binding to the HIV-1 LTR is not sufficient to increase viral expression in the primary human astrocyte.

Human astrocytes can be infected with HIV-1 both in vivo and in vitro. The amount of HIV-1 p24 structural protein production is low in comparison to that of the macrophage. Several weeks following infection or transfection, however, cocultivation with uninfected lymphocytes or stimulation with the cytokines TNF-alpha and IL 1-beta will increase viral production from this cell type. In the present study we demonstrate that phorbol 12-myristate 13-acetate (PMA) also increases HIV-1 p24 production from the primary human astrocyte. Using electrophoretic mobility shift assay (EMSA) in combination with supershift studies using specific antibodies, we demonstrate that PMA, like TNF-alpha, increases the p50/p65 form of NF-kB. Furthermore we demonstrate that the protein kinase inhibitor H7 inhibits PMA- and TNF-alpha-associated increases in HIV-1 expression at a time when it has little to no inhibitory effect on the associated increases in p50/p65 NF-kB. Thus, unless p50/p65 NF-kB or its binding is affected by H7 in a manner that cannot be resolved by EMSA, an increase in this form of NF-kB is not always sufficient to increase HIV-1 expression from the astrocyte.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Stimulation of HIV type 1 gene expression and induction of NF-kappa B (p50/p65)-binding activity in tumor necrosis factor alpha-treated human fetal glial cells.

In vitro, HIV-1 infection of human fetal glial cells initiates a noncytopathic, productive infection that results in a long-term persistence during which the viral genome remains latent. The cytokines tumor necrosis factor alpha (TNF-alpha) and interleukin 1 beta (IL-1 beta) reactivate HIV-1 gene expression in these cells, leading to production of infectious virus. Here we show that treatment of human fetal glial cells with TNF-alpha and IL-1 beta increase expression of the reporter gene chloramphenicol acetyltransferase (CAT) when placed under the control of the HIV-1 5' LTR. We also show that treatment of human fetal glial cells with TNF-alpha leads to increased binding of the nuclear transcription factor NF-kappa B (p50/p65) to a consensus kappa B-binding site present in the HIV-1 5'LTR. Our results suggest that TNF-alpha stimulation of HIV-1 gene expression in primary cultures of human fetal glial cells is mediated by an increase in binding of NF-kappa B (p50/p65) to the HIV-1 LTR. This is the first report documenting NF-kappa B-binding activity in primary cultures of human fetal glial cells.

Base Sequence↗
PubMed1994

HIV-1 infection of subcortical astrocytes in the pediatric central nervous system.

Early reports of pediatric HIV-1-associated neuropathology described the presence of viral particles in some astrocytes, implicating direct infection of the immature nervous system as a contributing factor to the observed neuropathology. Several recent reports suggest that in those astrocytes infected with HIV-1, the level of antigenic expression of the proviral genome is below the sensitivity limits of conventional histochemical techniques. Identification of these astrocytes would instead require the use of a highly sensitive radiolabeled DNA or RNA probe for in situ hybridization to detect the persistent viral nucleic acids. To test this hypothesis, we examined autopsy tissue from 12 infants and children with AIDS-associated encephalopathy for the presence of HIV-1-infected astrocytes using combined isotopic in situ hybridization for the detection of viral-specific nucleic acids and immunohistochemistry for the identification of astrocytes. We detected HIV-1 nucleic acids in astrocytes in subcortical white matter from four pediatric patients with moderate to extensive leukoencephalitis. While gp41 was detectable only on macrophages and multinucleated giant cells, HIV-1 Nef protein was present in cells morphologically identified as astrocytes in two of these patients, further suggesting that HIV-1 establishes a persistent rather than a productive infection in astrocytes. Subcortical astrocytes may therefore be an unrecognized reservoir for HIV-1 in the developing nervous system of some children with AIDS-associated leukoencephalitis.

AIDS Dementia Complex↗
PubMed1993

A mechanism of quinolinic acid formation by brain in inflammatory neurological disease. Attenuation of synthesis from L-tryptophan by 6-chlorotryptophan and 4-chloro-3-hydroxyanthranilate.

Quinolinic acid (QUIN), kynurenic acid (KYNA) and L-kynurenine (L-KYN) are neuroactive kynurenine pathway metabolites that accumulate in inflammatory neurological diseases. These increases were attributed to the induction of indoleamine-2,3-dioxygenase (IDO), the enzyme that converts L-tryptophan into L-KYN. Direct conversion of L-tryptophan into QUIN by brain tissue occurs in conditions of CNS inflammation, but not by normal brain tissue. To investigate whether increased activity of enzymes distal to IDO may determine L-KYN conversion to QUIN, rhesus macaques were inoculated with poliovirus directly into the spinal cord, as a model of focal inflammatory neurological disease (FASEB J. 6, 2977-2989, 1992). Induction of spinal cord IDO (35.9-fold) accompanied smaller, but proportional increases in kynurenine-3-hydroxylase (2.4-fold) and kynureninase (2.3-fold) activities, which were correlated to CSF and tissue QUIN levels, as well as to measures of inflammatory lesions. 3-Hydroxyanthranilate-3,4-dioxygenase activity was unchanged. Cerebrospinal fluid KYNA levels increased in proportion to both IDO activity and L-KYN accumulation, though kynurenine aminotransferase activity was unaffected. Cerebrospinal fluid neopterin, a marker of macrophage and immune activation, accumulated in proportion to the responsive enzymes and metabolites. The cell types involved in producing QUIN were investigated in vitro. Human foetal brain cultures consisting of astrocytes and neurons converted large quantities of [13C6]L-tryptophan into L-KYN when stimulated by gamma-interferon, but very little [13C6]QUIN was formed unless macrophages (THP-1 cells) were first added to the cultures (to model a key component of brain inflammation). [13C6]L-Tryptophan was converted into [13C6]QUIN by either gamma-interferon stimulated macrophages, or following intracisternal administration into poliovirus-infected macaques. Inhibitors of the kynurenine pathway, 6-chlorotryptophan and 4-chloro-3-hydroxyanthranilic acid, attenuated [13C6]QUIN formation by macrophages, and when co-infused with [13C6]L-tryptophan into poliovirus-infected macaques. These results suggest roles for increased activities of IDO, kynurenine-3-hydroxylase and kynureninase in accelerating the synthesis of QUIN, L-KYN and KYNA in conditions of brain inflammation. Macrophage infiltrates, and perhaps microglia, are important sources of QUIN, whereas constitutive brain cells and macrophages are sources of L-KYN. Drugs that inhibit kynurenine pathway enzymes attenuate QUIN formation in the CNS, and provide tools to examine the consequences of reduced QUIN accumulation.

3-Hydroxyanthranilic Acid↗
PubMed1993

Human immunodeficiency virus type 1 infection of the brain.

Direct infection of the central nervous system by human immunodeficiency virus type 1 (HIV-1), the causative agent of AIDS, was not appreciated in the early years of the AIDS epidemic. Neurological complications associated with AIDS were largely attributed to opportunistic infections that arose as a result of the immunocompromised state of the patient and to depression. In 1985, several groups succeeded in isolating HIV-1 directly from brain tissue. Also that year, the viral genome was completely sequenced, and HIV-1 was found to belong to a neurotropic subfamily of retrovirus known as the Lentivirinae. These findings clearly indicated that direct HIV-1 infection of the central nervous system played a role in the development of AIDS-related neurological disease. This review summarizes the clinical manifestations of HIV-1 infection of the central nervous system and the related neuropathology, the tropism of HIV-1 for specific cell types both within and outside of the nervous system, the possible mechanisms by which HIV-1 damages the nervous system, and the current strategies for diagnosis and treatment of HIV-1-associated neuropathology.

AIDS Dementia Complex↗
PubMed1992

Adjacent nuclear factor-1 and activator protein binding sites in the enhancer of the neurotropic JC virus. A common characteristic of many brain-specific genes.

JC virus is a neurotropic virus that causes the demyelinating disease progressive multifocal leukoencephalopathy in humans. In order to understand the neurotropic nature of this virus, we examined the binding of nuclear proteins to the viral regulatory region. A close association of nuclear factor-1 (NF-1) and Jun protein binding sites was found. These binding sites were either adjacent or overlapped each other. Depending on the order of binding, there was some interference of binding of the NF-1 protein by Jun even at a non-Jun binding site. This suggests that there may be a direct interaction between these proteins. Examination of the regulatory region of a number of genes expressed in the central and peripheral nervous systems revealed that many of these genes apparently have adjacent NF-1 and activator protein binding sites immediately upstream from the mRNA start site. Since it had been demonstrated that nuclear proteins from brain and non-brain cells could interact with these sites, it is probable that the NF-1- and Jun-related proteins which interact at these sites are involved in the basal activity of these genes. It appears that adjacent binding sites for NF-1 and Jun immediately upstream from the mRNA start site may be a characteristic of many genes expressed in the nervous system.

Base Sequence↗
PubMed1992

Relapsing and remitting human immunodeficiency virus-associated leukoencephalomyelopathy.

We describe a 33-year-old homosexual man with a steroid-responsive, remitting and relapsing leukoencephalopathy associated with recent human immunodeficiency virus type 1 (HIV-1) seroconversion. Biopsy of a parieto-occipital lesion revealed demyelination and astrogliosis with focal necrosis. Detailed investigations demonstrated no pathogens in the brain other than HIV-1. This patient illustrates that a neurological disorder clinically indistinguishable from multiple sclerosis may be the presenting manifestation of HIV-1 infection and may occur in the absence of clinically significant immunosuppression.

AIDS Dementia Complex↗