ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesThe majority of HIV-1-infected individuals manifest a plethora of central nervous system (CNS) diseases unrelated to opportunistic infections, including AIDS dementia complex, encephalitis, and various other disorders of the CNS. The present study sought to evaluate the cellular reservoirs and expression patterns of HIV-1 in brain tissue to gain further understanding of HIV-1 neuropathogenesis.DesignCNS tissue, obtained post-mortem from 22 patients with AIDS and four HIV-1-seronegative controls, was analyzed.MethodsCNS samples were evaluated using a combination ofin situDNA polymerase chain reaction (PCR), reverse transcriptase (RT)-initiatedin situPCR, and immunohistochemistry. By utilizing this triple-staining methodology, HIV-1 proviral DNA and HIV-1-specific mRNA can be identified at the single cell level.ResultsHIV-1 was detected in all 22 AIDS brain specimens and in none of the four brains from HIV-1-seronegative individuals. The most commonly infected cells in AIDS brains were microglia cells and macrophages, but variable levels of HIV-1 infection were demonstrated in many of the major histological cell types within the CNS, including neurons, microvascular endothelial cells (MVEC) and astrocytes. The presence of HIV-1-infected cells was not uniform with infected cells unevenly distributed throughout the brain parenchyma. The degree of HIV-1 mRNA expression varied from 39–65% of the cells in the CNS harboring HIV-1 provirus. Choroid plexus and MVEC exhibited relatively high levels of productive infection.ConclusionsThese findings demonstrate that several cell types in the CNS, in addition to microglia or macrophages, may become infected with HIV-1in vivowith variable levels of HIV-1 mRNA expression. The diverse cellular reservoirs for HIV-1 in the CNS may be critically linked to the molecular mechanisms involved in HIV-1 neuropathogenesis. In addition,in vivoinfection of MVEC, and possibly cells in the choroid plexus, may directly contribute to penetration of the blood-brain barrier by HIV-1.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo investigate whether variations of the conserved gp41 amino-acid sequence ELDKWA affect its binding or neutralization by monoclonal antibody (MAb) 2F5.Design and methodsNeutralization assays were performed with primary isolates from different HIV-1 subtypes and the sequences corresponding to the 2F5 epitope region were analysed. Studies of MAb 2F5 peptide reactivity were performed by spot analysis, using peptides immobilized on cellulose. The frequency of emergence of neutralization-resistant virus variants was determined by immune selection experiments in the presence of MAb 2F5.ResultsPrimary isolates from clades A, B and E were neutralized by MAb 2F5. Neutralization sensitivity correlated with the presence of the LDKW motif. A K-to-N change in the core sequence was identified in a neutralization-resistant patient isolate. Neutralization resistant virus variants that were selected in the presence of MAb 2F5 were found to contain D-to-N, D-to-E, or K-to-N changes within the LDKW sequence. Neither in natural isolates nor in variants obtained under immune selection conditions in the laboratory were changes in the L and W positions observed. Studies of MAb 2F5 binding to variations of the ELDKWA peptide confirmed that the changes at the first and last positions did not significantly reduce binding capacity, whereas amino-acid changes from D to N, D to E, and K to N almost completely abrogated binding of MAb 2F5.ConclusionSequence analysis of a variety of primary isolates suggests that the major determinant of MAb 2F5 binding corresponds to the amino-acid sequence LDKW. Naturally occurring andin vitroselected neutralization-resistant viruses contained changes in the D and K positions of the ELDKWA motif.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesTo investigate whether follicular dendritic cells (FDC) are target cells for HIV-1 infection.DesignBased on the principle that if FDC are true target cells, HIV-1 particles will bind to the surface of FDC and then invade their cytoplasm and nuclei.MethodsFreshly isolated tonsilar FDC were exposed to two strains (HE and JR-FL) of HIV-1 and cultured. They were then examined for HIV-1 replication, using p24 antigen-capture enzyme-linked immunosorbent assay, immunolabelling, and polymerase chain reaction (PCR) amplification. We used FDC clusters as the FDC source, since the culture system for FDC clusters has various advantages over other methods for the successful long-term culture of FDC.ResultsAfter 2 h incubation, particles of both HIV-1 strains bound to the surfaces of FDC, as well as to CD4+ T cells, although FDC do not have CD4 receptors. The FDC gradually released the particles into the culture supernatant. More HIV-1 particles were bound to fresh FDC than to dedifferentiated FDC or to control fibroblasts. However, HIV-1 particles bound to the FDC did not seem to enter the cells. We found no evidence of HIV-1 proviral DNA synthesis in FDC.ConclusionsOur results suggest that FDC are not readily infected with HIV-1in situ, although we found that FDCin vitrowere not infected by HIV-1.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo characterize the mechanism ofin vitroantigen-induced apoptotic T-cell death in the peripheral blood mononuclear cells (PBMC) of HIV-1-infected individuals.Design and methodsPBMC from HIV-1-infected and uninfected individuals were unstimulated or stimulated with HIV-1 envelope synthetic peptides (Env) or influenza A virus to determine the extent of antigen-stimulated apoptotic T-cell death, whether this death was limited to the CD4+ subset, and the effects of cytokines on T-cell death. Death was assessed by apoptotic nuclear morphology after 7 days of culture by fluorescence microscopy using a DNA-specific dye. Transwell cultures and supernatant transfers were utilized to test whether a soluble factor produced by HIV-positive PBMC induced death of HIV-negative T cells. Exogenous cytokines [interleukin (IL)-12, interferon (IFN)-γ, IL-4 and IL-10, as well as antibodies against endogenously produced cytokines (IL-4, IL-10, IL-12, and lymphotoxin) were tested for their ability to modulate death.ResultsAntigenic stimulation induced death in PBMC from HIV-positive donors, but not in PBMC from HIV-negative donors. Antigen-stimulated death was seen in CD4+ but not CD8+ T-cell subset from the HIV-positive patients. Apoptotic death was blocked by IL-12, IFN-γ, anti-IL-4, anti-IL-10, and anti-lymphotoxin, but not by anti-IL-12. Transwell and supernatant transfer experiments indicated that antigen-stimulated HIV-positive PBMC produced a factor that killed T-cell blasts. The factor was inhibited by anti-lymphotoxin, but not by anti-IL-10.ConclusionsStimulation of HIV-positive PBMC with CD4-dependent antigens results in selective death of CD4+ T cells that is modulated by cytokines. Our results suggest that apoptotic death is not limited to HIV-infected or HIV-specific T cells, but occurs in bystander cells. Lymphotoxin is a mediator of antigen-stimulated T-cell death in thisin vitromodel.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveThe purpose of this study was to investigate thein vitroprocessing ofCryptococcus neoformansby human alveolar macrophages from HIV-seropositive individuals compared with HIV-seronegative individuals.Design and methodsBronchoalveolar lavage (BAL) was performed on smoking and nonsmoking HIV-seropositive and seronegative volunteers. Lavage cells from the four groups were challengedin vitrowithC. neoformansand assessed for fungal binding, phagocytosis, and growth inhibition.ResultsThe results indicated that BAL cells from the smoking HIV-infected group had increased fungistatic activity compared with HIV-seronegative smokers (mean percentage growth inhibition ± SD, 77.5 ± 14.2 versus 59.1 ± 16.6%;P= 0.015). However, late-staged HIV-infected patients (Centers for Disease Control and Prevention class C3) were found to have decreased fungistasis compared with early stage A patients (63.8 ± 11.1 versus 83.0 ±2.2%;P<0.05). BAL cells recovered from HIV-seronegative smoking volunteers demonstrated reduced fungistatic activity when compared with BAL cells from HIV-seronegative nonsmokers (56.8 ± 8.8 versus 83.0 ±2.2%;P< 0.001). Smoking also induced a decrease in internalization ofC. neoformansby alveolar macrophages as assessed by confocal laser microscopy in both HIV-seronegative and HIV-infected groups.ConclusionWe conclude that BAL cells from early-stage HIV-1-infected individuals do not have an intrinsic defect in fungistasis ofC. neoformans.In fact, it appears that BAL cells from HIV-seropositive people are activated for fungistasis in early HIV infection, although fungistatic activity declines as the disease progresses. Incidentally noted was the finding that smoking decreases the internalization ofC. neoformansin both HIV-infected and HIV-seronegative individuals, suggesting the possibility that smoking might enhance the susceptibility to cryptococcosis.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo report the clinical response to atovaquone in HIV-1-infected patients with symptomatic intestinal microsporidiosis.DesignA retrospective review of a cohort of AIDS patients with symptomatic intestinal microsporidiosis who received atovaquone.SettingInfectious Disease Program of the Grady Memorial Hospital, Veterans Affairs Medical Center and private physicians' offices in Atlanta, Georgia.Patients and methodsHIV-1-infected patients (n = 371) were offered a complete stool evaluation and monthly follow-up. Among them, 22 were diagnosed with intestinal microsporidial infection using stool smears stained with modified trichrome stain. Species confirmation was made by light microscopy or electron microscopy on small intestinal biopsy specimens in some patients.Main outcome measureDifferences in symptoms, number of stools, and body weight were compared before and after a minimum of 1 month of atovaquone therapy.ResultsEight patients received atovaquone treatment. The mean onset of clinical improvement after beginning treatment was 13 days (SEM, ± 2). The mean number of stools per day decreased from 10 ± 2.5 to 2 ± 1 (P= 0.02, paired t test). The mean weight gain was 3 ± 2 kg. The parasite was continuously present in the repeated stool specimens. However, semiquantitative analysis performed on two patients' stool specimens showed a decreased parasite burden. Four patients underwent small intestinal endoscopy with control after a 1 -month period. The morphology of the spores by light microscopy was consistent withEnterocytozoon bieneusiin all four patients. Only one out of these four patients demonstrated a decrease in parasite burden in the biopsy specimen. Ultrastructural analysis performed in another of these four patients following treatment demonstrated the presence of electron-dense granules in spores, suggestive of toxic effects.ConclusionAtovaquone demonstrates promise as a symptomatic treatment for intestinal microsporidiosis. A double-blind and placebo-controlled clinical trial is currently in progress.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo study development of phenotypic and genotypic resistance against zidovudine (ZDV) and didanosine (ddl) during 24 months of mono- and monthly alternating therapy.PatientsForty-six patients, not previously treated with antiretroviral drugs, were included in the study.MethodsZDV and ddl sensitivity were determined in a biological assay based on production of HIV antigen in cultures of CD4+ lymphocytes. The ZDV-associated mutations at codon 41 and 215, and the ddl-associated mutation at codon 74 of the reverse transcriptase (RT) gene were analysed using selective polymerase chain reaction on DNA from peripheral blood mononuclear cells. The biological phenotype [syncytium-inducing (SI)/non-SI (NSI)] of the viral isolates was assessed using a MT2 assay.ResultsOf the patients, 82% in ZDV therapy and 73% in alternating therapy developed phenotypic resistant HIV [median inhibitory concentration (IC50) > 0.1 μ.M]. Patients treated for 1 year with ddl (monotherapy or alternating) had significant higher ddl IC50values than patients in ZDV monotherapy. During ZDV and alternating therapy, 67 and 75% of the patients, respectively, developed mutations in RT codon 41, whereas 83 and 75%, respectively, developed mutations in codon 215. In patients treated with ddl, 60% developed mutations in codon 74, whereas none of the patients in either alternating ZDV/ddl or ZDV therapy developed this mutation. Forty-six per cent of the patients had SI HIV at start of therapy. Four patients switched from SI to NSI during either ZDV, ddl or alternating therapy. Faster development of resistance was associated with the SI phenotype.ConclusionsNo difference in either phenotypic ZDV or ddl resistance, or genotypic ZDV resistance could be demonstrated during monotherapy or monthly alternating ZDV/ddl therapy, whereas genotypic ddl resistance (mutation in RT codon 74) only were detected in patients in ddl monotherapy. In addition, we found that development of phenotypic and genotypic resistance was faster in patients harbouring SI isolates, and that switches from SI to NSI during therapy was independent of the type of therapy.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectivesNevirapine is a non-nucleoside reverse transcriptase inhibitor of HIV-1 which exhibits synergyin vitrowith zidovudine (ZDV) and also is active against ZDV-resistant HIV. We evaluated the activity and safety of nevirapine in combination with ZDV in patients receiving long-term ZDV therapy.MethodsWe conducted a randomized, open-label, controlled 28-week study of nevirapine (200 mg daily for 2 weeks followed by 200 mg twice daily for 26 weeks) and continued ZDV (500–600 mg daily) versus continued ZDV alone in 49 HIV-1 p24 antigenaemic patients with CD4+ lymphocyte counts < 500×106/l and who had been treated with ZDV for at least 6 months.ResultsAddition of nevirapine to ZDV resulted in a significant and rapid reduction in circulating RNA load (mean, 0.65), a mean CD4+ lymphocyte rise of 34×106/l, a reduction in serum β2-microglobulin and a median fall in immune complex dissociated p24 antigen levels of 69%. These changes remained statistically significant for 4, 4, 12 and at least 28 weeks, respectively. The principal adverse event due to nevirapine was a hypersensitivity reaction comprising rash with or without fever and mucosi-tis in eight (32%) patients, which was dose-limiting in seven patients.ConclusionNevirapine exhibits significant although transient anti-HIV activity in ZDV-pretreated patients but its use is frequently associated with a hypersensitivity reaction.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

ObjectiveTo assess the proportion of, and the characteristics associated with, Kaposi's sarcoma (KS) and non-Hodgkin's lymphomas (NHL) in children (0–12 years) and adolescents (13–19 years) at AIDS diagnosis, in Europe and in the United States (US).DesignComparison of the proportions of KS and NHL at AIDS diagnosis, according to various characteristics, by means of the European Non-Aggregate AIDS Data Set (4400 children and 764 adolescents) and the US AIDS Public Information Data Set (4710 children and 1064 adolescents) updated to June 1993.MethodsComparison of data was made using odds ratios (OR) and corresponding 95% confidence intervals.ResultsBetween 0 and 19 years, the proportion of KS at AIDS diagnosis (0.5% in Europe and 0.9% in the US) increased with age, particularly in Europe, and was higher in males than in females. It decreased with time in the US but not in Europe. In the US, black children showed a nearly threefold excess of KS as compared with white children. Adolescents who reported homosexual intercourse with other males had significantly elevated risks of KS, both in Europe (OR, 6.3) and in the US (OR, 21.1). NHL was diagnosed in 0.9% of children in Europe and in 1.5% in the US. The proportion of NHL significantly increased with age (3.1% among adolescents in Europe and 3.0% in the US), and was higher in males than in females. In the US, NHL tended to decline in proportion with all AIDS cases over time and showed a nearly twofold higher frequency in white children. No associations emerged between NHL and HIV transmission category.ConclusionsIn agreement with incidence rates in the general paediatric population, but at variance with AIDS in adults, NHL turned out to be more common than KS in children and adolescents with AIDS. A strong excess of KS was already present in adolescents who reported homosexual intercourse.

ISSN:0269-9370    

出版商:OVID    

年代:1996

数据来源: OVID