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Biomedical subjects

L Pulliam

Publications and source records attributed to L Pulliam.

At least 19 recordsLinked to original sources
PubMed2001

CPI-1189 attenuates effects of suspected neurotoxins associated with AIDS dementia: a possible role for ERK activation.

Individuals infected with the human immunodeficiency virus (HIV) often experience a dementia characterized by mental slowing and memory loss. Motor dysfunction may also accompany this condition. The pathogenesis of the dementia is not known, but microscopic examination of brain tissue from those afflicted shows evidence of chronic inflammation, reactive gliosis and cell death. Neurotoxic factors produced from activated macrophage or microglial cells such as tumor necrosis factor-alpha (TNFalpha), gp120 and quinolinic acid have been implicated as agents for the cell death which often appears to occur by an apoptotic mechanism. CPI-1189, a drug currently undergoing clinical evaluation as a treatment for the dementia associated with AIDS, is shown in this paper to mitigate apoptosis induced by TNFalpha, gp120, and necrosis induced by quinolinic acid. In addition, CPI-1189 mitigates the cell death produced by supernatants from cultured macrophages obtained from patients with AIDS dementia. The exact mechanism by which CPI-1189 prevents neurotoxicity is not known; however, protection from TNFalpha and supernatant-induced toxicity does not appear to involve NFkappaB translocation, and appears to be associated with an increase in activated ERK-MAP kinase. These findings may have implications for other neurological diseases where apoptotic cell death contributes to neurodegeneration.

AIDS Dementia Complex↗
PubMed2001

Interleukin-1beta up-regulates expression of neurofilament light in human neuronal cells.

Elevated expression of interleukin-1 (IL-1beta), a pro-inflammatory cytokine secreted by activated microglia, is a pathogenic marker of numerous neurodegenerative processes including Alzheimer's disease (AD). We have characterized a link between IL-1beta and the 68-kDa neurofilament light (NF-L) protein, which is a major component of the neuronal cytoskeleton. Using human brain aggregate cultures, we found that IL-1beta treatment significantly increased NF-L expression in primary neurons. Analysis of mRNA levels demonstrated elevated NF-L expression within 72 h while imaging of neurons by immunofluorescent staining for NF-L confirmed IL-1beta-induced NF-L protein expression. These observations suggest a potential inflammatory-induced mechanism for deregulation of an important cytoskeletal protein, NF-L, possibly leading to neuronal dysfunction.

Alzheimer Disease↗
PubMed2000

Elevation of CD69+ monocyte/macrophages in patients with Alzheimer's disease.

In this report, we examined the presence of the activation marker, CD69, on monocytes derived from patients with Alzheimer's disease (AD). We have previously shown that patients with AIDS dementia had an elevated percentage of a CD14+/CD69+ subset and that conditioned media from these M/M phi cultures were toxic to neural cultures. We therefore postulated that patients with AD might likewise have a higher monocyte subset and that this would be associated with neural toxicity. Flow analysis showed that AD patients (n = 13) had a higher percentage of CD69+ M/M phi over age matched controls (n = 14); this trend was statistically significant (p = 0.006). Side scatter (SSC), a measure of cellular granularity was also elevated in AD patients (p = 0.02). The elevated expression of human leukocyte antigen (HLA-DR) was not found to be significant between age-matched controls and AD patients. When conditioned media from M/M phi from five AD and two control patients were evaluated for neurotoxicity, three of the five culture supernatants from AD patients induced apoptosis in neural cell aggregate cultures. Electrophoretic mobility shift assays revealed that these three supernatants also triggered NF-kappaB translocation to the nucleus. Surprisingly, in vitro neurotoxicity was induced by M/M phi supernatants having a lower percentage of CD14+/CD69+ cells. Elevation of the CD14+/CD69+ subset in AD patients may therefore represent a manifestation in the peripheral blood of the pathological events occurring in the brain but may not be directly involved in neural cell toxicity.

Alzheimer Disease↗
PubMed2000

Transgenerational health promotion.

The Adult Health and Development Program (AHDP) is an intergenerational, interdisciplinary health promotion and rehabilitation program in which nursing and other college students are paired with older adults to engage in activities to improve their health and well-being. The purpose of this article is to describe resources and strategies used to implement a new program. The University of Delaware's program uses the ACAEM Paradigm developed by the AHDP at the University of Maryland where the program has existed for 27 years. However, the University of Delaware emphasizes the concepts of transition as described by Schumacher and Meleis and adult learning theory. Older adults are often the most open to education and other forms of support when they need help in making a change or transition in their lives. Schumacher and Meleis contend that transitions are a central concept in nursing and propose a model of transition in which education is the primary modality for preparing for transitions. The model also specifies ways to measure desirable transition outcomes.

Adaptation, Psychological↗
PubMed1999

A trans-receptor mechanism for infection of CD4-negative cells by human immunodeficiency virus type 1.

Chemokine receptors, particularly CCR5 and CXCR4, act as essential coreceptors in concert with CD4 for cellular entry by human immunodeficiency virus type 1 (HIV-1; reviewed in [1]). But infection of CD4(-) cells has also been encountered in various tissues in vivo, including astrocytes, neurons and microvascular endothelial cells of the brain [2] [3] [4] [5] [6], epithelial cells [5] [7], CD4(-) lymphocytes and thymocytes [8] [9], and cardiomyocytes [10]. Here, we present evidence for the infection of CD4(-) cell lines bearing coreceptors by well-known HIV-1 strains when co-cultured with CD4(+) cells. This process requires contact between the coreceptor-bearing and CD4(+) cells and supports the full viral replication cycle within the coreceptor-bearing target cell. Furthermore, CD4 provided in trans facilitates infection of primary human cells, such as brain-derived astrocytes. Although the pathobiological significance of infection of CD4(-) cells in vivo remains to be elucidated, this trans-receptor mechanism may facilitate generation of hidden reservoirs of latent virus that confound antiviral therapies and that contribute to specific AIDS-associated clinical syndromes.

CD4 Antigens↗
PubMed1999

Expression of binding sites for beta chemokines on human astrocytes.

Astrocytes are major sources of chemokines and are thus critical effectors of central nervous system (CNS) inflammation. However, it is as yet unclear whether these cells, like leukocytes, also possess receptors for chemokines (CCRs). To address this issue, we utilized a novel fluorescence approach to detect qualitatively and quantitatively binding sites for biotinylated derivatives of the beta chemokines monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) on cultured human fetal astrocytes. Both chemokines were found to bind to the surface of astrocytes in a specific and saturable manner and with the high-affinity typical of these chemokines' binding to leukocyte CCRs. Binding of labeled MCP-1 and of labeled MIP-1alpha was antagonized by the respective unlabeled homologue but not by the unlabeled heterologous chemokine. Binding of labeled MCP-1 was also inhibited by unlabeled MCP-3, both of which are ligands for CCR2. In a parallel manner, binding of labeled MIP-1alpha was first shown to be attenuated by unlabeled RANTES, both of which recognize CCR1 and CCR5, and then separately antagonized by MCP-3 and MIP-1beta, which bind to CCR1 and CCR5, respectively. Finally, binding of both labeled chemokines was observed to be modulated in response to astrocyte stimulation by proinflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), further indicating that these binding sites are subject to regulation and, thus, likely to be physiologically responsive. Collectively, these results indicate that binding sites exhibiting characteristics of chemokine receptors exist on human astrocytes. Such sites might function in the recruitment of both astrocytes and leukocytes to specified brain regions during physiological and pathophysiological processes.

Astrocytes↗
PubMed1998

Differential modulation of cell death proteins in human brain cells by tumor necrosis factor alpha and platelet activating factor.

Programmed cell death contributes to the morbidity and mortality of several neurological disorders including stroke, Alzheimer's disease and human immunodeficiency virus (HIV)-associated dementia. Patients with HIV dementia show evidence of programmed cell death in brain. In vitro data demonstrates several neurotoxic products of macrophage infection that cause neural cell death, including tumor necrosis factor alpha (TNFalpha) and platelet activating factor (PAF). We treated human brain aggregate cultures with these cytokines and determined their effect on the mRNA and protein levels for Bcl-2, Bcl(x) and Bax alpha. TNFalpha and PAF differentially regulate the Bcl-2 family of proteins at a post-transcriptional level. Following TNFalpha treatment, Bcl-2 protein is significantly decreased, and at least one additional Bax isomer emerges. Bcl(xL) protein is slightly increased after treatment with either cytokine. We demonstrated that overexpression of Bcl-2 in brain aggregate cultures protects cells from TNFalpha-induced damage but has no effect on cell damage induced by PAF. We conclude that Bcl-2 and Bax alpha proteins play significant roles in modulating neural cell death from TNFalpha- but not from PAF-induced cell damage.

AIDS Dementia Complex↗
PubMed1998

Quantification of neurotoxicity and identification of cellular subsets in a three-dimensional brain model.

Imaging of cells in a large intact three-dimensional tissue remains difficult. Quantification and identification of cell damage in a mixed culture system has been limited by the inability of fluorescent probes to discriminate types of cellular death and penetrate tissue more that 100 microm thick. We have investigated several probes in combination with neural cell-specific antibodies to quantify cell damage in the presence of several toxins. Acridine orange and ethidium bromide were excellent for determination of cell viability, death by necrosis, or apoptosis in thick brain tissue aggregates. Calcein and ethidium homodimer were effective on live/ dead stains, and the Syto dyes 11 and 13 worked well for quantification of all cells in the brain aggregate model. By using these combinations of dyes in conjunction with confocal microscopy, we were able to quantify neural cell damage without disrupting the three-dimensional environment.

Apoptosis↗
PubMed1997

Unique monocyte subset in patients with AIDS dementia.

BACKGROUND: 15-30% of patients infected with HIV will develop a debilitating dementia. Whilst HIV enters the brain soon after infection, presumably within monocyte-derived macrophages, not all patients with HIV become demented. Blood monocytes probably cross the blood-brain barrier and give rise ultimately to parenchyma macrophages. We looked for a specific monocyte subset in AIDS patients with dementia. METHODS: Peripheral blood monocytes from three groups were compared: AIDS patients with (n = 12) and without (n = 11) dementia, and ten HIV seronegative healthy controls. We used flow cytometry to analyse monocytes, and cell lysis and apoptosis assays to examine monocyte effects on human brain cells in vitro. FINDINGS: We found a unique subset of monocytes in patients with AIDS dementia. These monocytes were more dense and granular and expressed CD14/CD16 and CD14/CD69. Means (SD) for CD14/CD16 in HIV-negative controls and in AIDS non-dementia and AIDS dementia patients were 6.5% (4), 16% (13), and 37% (21), respectively (p = 0.008 between the two groups of patients). The corresponding means for CD14/CD69 were 7% (6), 8% (10), and 69% (18) (p < 0.0001). INTERPRETATION: CD69 is a member of the natural-killer-cell gene complex that is expressed after activation. Supernatants from cultures containing these dense cells can trigger apoptosis of human brain cells in vitro. The monocyte subset we found in patients with AIDS dementia might enter the brain and expose neural cells to toxic factors.

AIDS Dementia Complex↗
PubMed1996

Monokine products as predictors of AIDS dementia.

OBJECTIVE: To determine whether or not soluble factors produced by peripheral blood mononuclear cells (PBMC) can predict AIDS dementia. DESIGN AND METHODS: PBMC were isolated from individuals with and without AIDS dementia complex (ADC) to determine if the levels of cytokines tumour necrosis factor (TNF)-alpha and interleukin (IL)-6, or the production of a neurotoxic substance, were significantly different. PBMC were studied after determining that the numbers of monocyte-derived macrophages isolated by adherence were highly variable from patients with ADC compared with individuals without ADC. We prospectively studied 16 AIDS dementia patients, 13 healthy HIV-seropositive individuals, and eight sero-negative controls. Supernatants from PBMC were assayed for TNF-alpha, IL-6 and alone for neurotoxicity on human neural cells in vitro. RESULTS: We observed a trend towards worse cognitive and motor performance in patients suffering from ADC but who had no opportunistic infections ('pure dementia'; n = 8). Levels of PBMC IL-6 were significantly higher in 'pure dementia' patients. There was a trend towards lower levels of PBMC TNF-alpha in the group of patients who had both dementia and opportunistic infections compared with "pure dementia' patients. Supernatant from PBMC of ADC patients was significantly more neurotoxic than that from healthy HIV-seropositive individuals. CONCLUSIONS: Macrophage isolation from PBMC of patients with ADC was altered. Soluble factors produced from PBMC were significantly more neurotoxic than soluble factors from PBMC of healthy HIV-seropositive individuals. PBMC production of TNF-alpha and IL-6 was not a significant predictor of ADC.

AIDS Dementia Complex↗
PubMed1995

Human cytomegalovirus induces IL-6 and TNF alpha from macrophages and microglial cells: possible role in neurotoxicity.

Human cytomegalovirus (HCMV) can frequently infect the central nervous system (CNS) in the setting of immunosuppression such as transplantation and infection with the human immunodeficiency virus (HIV). Our laboratory previously reported that HCMV infection of human brain aggregates preferentially infected a microglial/macrophage (M/M) and caused a neuropathology that differed between strains and could occur in the absence of antigen expression. We extended these studies by infecting a human brain cell aggregate model with four low passage clinical isolates of HCMV. Two patterns of cytopathology emerged after infection; a lacy eosinophilic appearance or a glial nodular formation concomitant with a decreased aggregate size. None of the infections were positive for HCMV antigen; however, all were positive for HCMV DNA. We also infected primary macrophages and microglial cells with the same HCMV isolates. Microglial cells were more susceptible to HCMV infection resulting in a lytic infection. Production of potentially neurotoxic cytokines, IL-1, IL-6 and TNF alpha, from HCMV-infected macrophages and microglial cells were evaluated to explain brain aggregate cytopathology. Supernatants from HCMV-infected macrophages and microglial cells produced similar levels of TNF alpha (< 30 pg ml-1) but showed strain and cell source variation in the production of IL-6; microglial cultures produced > 4 fold higher levels. None of the supernatants contained IL-1. Treatment of brain aggregates with either IL-6 or TNF alpha resulted in morphologic alterations and/or a decrease in size consistent with HCMV infection or supernatant treatment.

Brain↗
PubMed1995

The HIV envelope protein gp120 is toxic to human brain-cell cultures through the induction of interleukin-6 and tumor necrosis factor-alpha.

OBJECTIVE: To investigate the induction of cytokines as a possible mechanism for the neurotoxicity of the HIV-1 envelope protein gp120. DESIGN: The gp120 protein was tested directly on primary human brain cultures to examine its ability to induce cytokines and its neurotoxicity on human neural cells because gp120 is known to be toxic to rodent ganglion cultures, and neural cells such as astrocytes and microglia produce cytokines when stimulated. METHODS: Primary cultures of human brain cell aggregates, astrocytes and macrophages were exposed to HIV-1 recombinant (r) gp120SF2. Induction of cytokines was assayed by enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR); neurotoxicity of rgp120SF2 and interleukin (IL)-6 on human brain cultures was examined by electron microscopy. RESULTS: ELISA and RT-PCR studies revealed that rgp120SF2 induced IL-6 and tumor necrosis factor (TNF)-alpha in brain cultures; IL-6 could also be induced by TNF-alpha added to brain cultures. Both IL-6 and TNF-alpha were upregulated in astrocytes and macrophage cultures on rgp120SF2 treatment. Ultrastructural studies demonstrated that IL-6 treatment for 72 h induced large cytoplasmic vacuoles in neural cells with morphology consistent with neurons; rgp120SF2 treatment for 7 days resulted in chromatin condensation along the inner margins of nuclear envelopes of neural cells. CONCLUSIONS: Our results demonstrated that HIV-1 rgp120SF2 can upregulate at least two known neurotoxic cytokines, IL-6 and TNF-alpha, which may injure neural cells and contribute to the neuropathology observed in AIDS dementia patients.

Astrocytes↗
PubMed1994

Prospective risk stratification in renal transplant candidates for cardiac death.

In previous studies to predict future cardiac death of patients undergoing evaluation for renal transplantation, noninvasive or invasive testing of all, or nearly all, patients has been used. In an attempt to decrease the cost of cardiac risk assessment, we prospectively used a two-tiered cardiac risk assessment algorithm on 189 consecutive patients referred for renal transplant evaluation. First, patients were stratified by clinical characteristics of age > or = 50 years, history of angina, insulin-dependent diabetes, congestive heart failure, or abnormal electrocardiogram (excluding left ventricular hypertrophy). Patients having none of these risk factors (n = 94) were considered at low risk for cardiac events and underwent no further cardiac evaluation. Patients with one or more of the cardiac risk factors (n = 95) were considered to be in a high-risk group and were required to undergo further evaluation with thallium myocardial scintigraphy. Follow-up of patients was for 46 +/- 16 months. Cardiac mortality was significantly higher in the clinical high-risk group compared with the clinical low-risk group (17% v 1%, respectively; P < 0.001). Further cardiac risk stratification was evident by thallium myocardial scintigraphy. Patients with reversible thallium defects had significantly higher cardiac mortality rates than patients with no thallium defects (23% v 5%, respectively; P < 0.05). Fixed thallium defects also had predictive value for cardiac mortality (29%,; P < 0.05), but deaths in this fixed defect group tended to occur later in the follow-up period. The initial clinical stratification obviated the need for further noninvasive or invasive testing in nearly half of the renal transplant candidates.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Investigation of HIV-infected macrophage neurotoxin production from patients with AIDS dementia.

The mechanism for AIDS dementia may involve the production of toxic cytokines. Since macrophage/microglia are the infected cells in the brain, we were interested in the production of some of the same cytokines by HIV-infected macrophages from patients with AIDS dementia. HIV-infected macrophages from 11 patients with AIDS dementia were cultured and evaluated for p24, cytomegalovirus (CMV) DNA, and the production of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF alpha) and other neurotoxic factors. The percentage of HIV macrophage infectivity did not correlate with the severity of dementia nor did the presence of CMV. The production of IL-6 and an unidentified neurotoxin did not correlate with HIV macrophage infectivity suggesting that these soluble factors are strain specific. Production of TNF alpha by HIV-infected macrophages was relatively low (< 1-35 pg/ml) and may not be a significant factor in toxicity.

AIDS Dementia Complex↗
PubMed1993

HIV-1 envelope gp120 alters astrocytes in human brain cultures.

The majority of AIDS patients will experience some degree of dementia induced by human immunodeficiency virus (HIV-1). In this study, we report that treatment of human brain tissue with envelope gp120 of HIV-1 did not cause neuronal death but did cause astrocyte alterations and/or death. Human astrocyte cultures showed decreased expression of glial fibrillary acidic protein (GFAP), as well as the diminution of a major protein of 66 kDa. These findings are similar to the in vitro changes observed when astrocytes are exposed to ammonia and in vivo changes observed in experimental hepatic encephalopathy. We hypothesize that AIDS dementia may partially involve a perturbation of astrocyte function by gp120 that could indirectly impair neuronal function.

AIDS Dementia Complex↗
PubMed1992

The two-view radionuclide ventriculogram. Advantages of the LPO view.

This report is a prospective study of 33 male patients who underwent both contrast ventriculography (CVG) and radionuclide ventriculography (RVG) within a 24-hour period. Expert, blinded observers graded the left ventricle's regional wall motion (RWM) in the left anterior descending (LAD), left circumflex (LCx), and posterior descending arterial (PDA) distributions on right anterior oblique (RAO), and left anterior oblique (LAO) CVGs, and on anterior (ANT), LAO, 70 degrees left anterior oblique (LAO70), and left posterior oblique (LPO) RVGs. When statistically compared with CVG RWM standard data, RVG studies composed of LAO and LPO views were equal to the RVG studies composed of ANT, LAO, and LAO70 views in assessment of the LAD and LCx distributions. The RVG with LAO and LPO views was superior to the RVG with ANT, LAO, LAO70 in the detection of the posterior descending artery RWM. The authors conclude that accurate assessment of RWM is efficiently performed with the RVG composed of LAO and LPO views.

Coronary Artery Disease↗