摘要:

Objectives:The prevalence of erectile dysfunction in HIV-infected men is estimated to be 33%. Sildenafil citrate (Viagra; Pfizer Ltd, Sandwich, Kent, UK) is the first oral drug for this condition. Since sildenafil and the protease inhibitors are both metabolized by, and act as inhibitors of cytochrome P450 3A4, we evaluated the pharmacokinetics of the combination sildenafil plus indinavir in HIV-infected patients.Design and methods:Six patients at steady state in treatment with indinavir participated in the study. On the first day blood samples for indinavir assay were drawn at times 0, 1, 2, 3, 4, 6 and 8 h after dosing. On the second study day patients received a single dose of 25 mg of sildenafil in addition to their routine morning medication. Blood samples were taken as described. Separated plasma was stored at -80°C until analysis by high performance liquid chromatography. In a parallel study, the effect of indinavir, ritonavir, saquinavir and nelfinavir on thein vitrohepatic metabolism of sildenafil was assessed.Results:The geometric mean area under the concentration curve for 0-8h (AUC0-8h) and maximum plasma concentration (Cmax) for indinavir were 19.69μg/mlh (range, 9.19-31.99μg/mlh) and 7.02μg/ml (range, 2.33-16.17μg/ml), respectively, on the first study day. In the presence of sildenafil, the mean AUC0-8hand Cmaxof indinavir were 22.37μg/mlh [range, 10.08-37.25μg/mlh; 95% confidence interval (CI) for difference between means, -15 to 13.25) and 9.11μg/ml (range, 3.41-22.78μg/ml; 95% CI, -13 to 6.37), respectively.The geometric mean AUC0-8hand Cmaxfor sildenafil were 1631 ng/mlh (range, 643-2970 ng/mlh) and 384 ng/ml (range, 209-766 ng/ml) respectively. The AUC for sildenafil was 4.4 times higher than data from historical controls given either 50mg or 100 mg of sildenafil and dose normalized to 25 mg. Indinavir was a potent inhibitor of sildenafil hepatic metabolismin vitro[concentration producing 50% inhibition of control enzyme activity (IC50) = 0.39 ± 0.17 μM, mean ± SD].Conclusions:Co-administration of sildenafil 25 mg did not significantly alter the plasma indinavir levels. However, plasma sildenafil AUC was markedly increased in the presence of indinavir compared with historical controls. From thein vitrodata, the mechanism of increase is indinavir inhibition of the hepatic metabolism of sildenafil. The magnitude of this interaction suggests a lower starting dose of sildenafil may be more appropriate in this clinical setting.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:A phase I trial was conducted to evaluate the safety and immunogenicity of an HIV synthetic peptide vaccine in HIV-seropositive individuals. The immunogens used in this study were PCLUS 3-18MN and PCLUS 6.1-18MN envelope peptides.Methods:Eight HIV-infected patients received six subcutaneous injections of 160μg PCLUS 3-18MN in Montanide ISA 51 and were followed longitudinally for a year after the first immunization. Peripheral blood mononuclear cells (PBMC) were tested for peptide-specific T helper and cytotoxic T cell (CTL) responses, HIV-1MNneutralizing antibodies and antibodies against HIV PCLUS 3 and P18 MN peptides.Results:PCLUS 3-18MN-specific T helper responses were significantly increased at 36 weeks (P<0.05, after adjustment for multiple comparisons) following initial immunization with PCLUS 3-18MN. A P18MN-specific CTL response, not present prior to vaccination, was observed after immunization in one patient. Serum HIV-1MN-neutralizing antibody titers increased in each of the three patients who had low titers prior to immunization. Plasma HIV RNA levels and CD4 cell counts did not change appreciably during the study period.Conclusions:This trial demonstrates that both peptides can be safely administered to HIV-infected individuals and that PCLUS 3-18MN induces increases in HIV peptide-specific immune responses.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objectives:Dendritic cells (DC) are potential first target cells in sexually transmitted HIV-1 infection. They are also considered to be central in the activation of naive T cells, which thereupon can become permissive for HIV-1. In addition, activated DC express effector molecules, which likely contribute to the direction of T helper (Th1/Th2)-specific immune responses.Methods:The capacity of cytokine and chemokine production inin vitroDC infected and uninfected with HIV-1 was assessed by enzyme-linked immunosorbent assay (ELISA) and byin situimmunocytochemical detection at the single cell level. Fluorescentin situ5‚-nuclease assay (FISNA) was used for quantitative evaluation of HIV-1gag-positive cells.Results:Macrophage-tropic HIV-1 effectively infected 20-40% ofin vitrocultured DC. However, this activity alone did not induce detectable cytokine or chemokine protein expression in DC. In contrast, lipopolysaccharide (LPS) stimulation of these HIV-1-infected DC resulted in a significantly increased level of cells producing tumour necrosis factor agr; (TNF-agr;) and interleukin (IL) 1&bgr; but reduced frequencies of cells producing IL-1 receptor antagonist (IL-1ra) compared with the LPS-stimulated but uninfected DC cultures (P<0.05). Furthermore, an extensive production of the &bgr;-chemokines [RANTES, macrophage inflammatory proteins (MIP) 1agr;? and 1&bgr;] was detected in DC in response to both LPS and HIV-1 plus LPS.Conclusions:These findings indicate that HIV-1 infected DC may have an increased proinflammatory activity. Elevated production of cytokines such as TNF-agr; and IL-1&bgr; and reduced IL-1ra may contribute to enhanced replication of HIV-1 in bystander T cells. Gram-negative bacterial infection and gut-associated bacterial translocation in HIV-1-infected individuals may also result in endotoxin-mediated reactivation of HIV-1 in bystander CD4 CD45RO T cells caused by the increased production of proinflammatory cytokines in DC.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To analyse the expression and specificity of co-receptors for the entry of HIV and simian immunodeficiency virus (SIV) into megakaryocytes.Design and methods:The expression of co-receptors was determined by flow cytometric analysis in combination with reverse transcription-polymerase chain (RT-PCR) reaction. The specificity of co-receptors in virus entry was determined by the infection of HIV-1 pseudotyped with X4- (HXB2), R5- (YU2), or R5X4-tropic (89.6) envelope proteins of HIV-1 or with envelope proteins of SIVpbj1.9.Results:The model human erythroleukemia (HEL) cell line, exhibiting megakaryocytic-like properties, expressed CCR5, CCR3, CXCR4, and GPR15/BOB, and all viruses except YU2 (R5) efficiently entered the cells. The blocking of virus entry with specific chemokines showed that the entry of HXB2 (X4) was impaired by SDF-1&bgr; but not by other chemokines, indicating that CXCR4 was a major co-receptor for the entry of HXB2. Primary human bone marrow megakaryocytes displayed a different repertoire of co-receptor expression from that of HEL cells, as all viruses except YU2 efficiently entered these cells. However, chemokine blocking experiments showed that the entry of HXB2 into primary bone marrow megakaryocytes was insufficiently blocked by SDF-1&bgr; compared with the entry into HEL cells, suggesting that alternative co-receptors could be employed for the entry of X4 virus into bone marrow cells.Conclusion:These data suggest that cells of megakaryocytic lineage are susceptible to infection by X4 viruses, with less marked susceptibility to R5 isolates, and that SDF-1&bgr; efficiently blocks the infection of HEL cells but not of primary bone marrow megakaryocytes. Our data reveal that novel co-receptors are probably utilized for the entry of X4 virus into megakaryocytes.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background:Assembly of human immunodeficiency virus type 1 (HIV-1) occurs at the level of the plasma membrane of the host cell. During this process HIV incorporates significant quantities of cell surface-derived molecules into its lipid bilayer including human leucocyte antigen (HLA) class I and II, intercellular adhesion molecule-1 and lymphocyte function antigen-1. Several studies indicate that virion-bound host-cell-derived molecules are functional and affect the biological properties of HIV-1. Virion-associated HLA class II and intercellular adhesion molecule-1 enhance the infectivity of T-cell line-adapted (TCLA) viruses. No role for virion-associated HLA class I molecules has yet been identified.Objective:To investigate the role of HLA class I molecules in HIV replication and infectivityMethods:HLA class I negative human cells lines transfected with the HLACw4gene were infected with different TCLA viruses as well as primary X4 isolates. The infectivity of HLA Cw4 positive and negative viruses was determined on indicator cell lines and on phytohaemagglutinin-activated peripheral blood mononuclear cells. An entry polymerase chain reaction assay was used to determine differences in entry-competence of Cw4 positive and negative viruses. The expression of selected gp120 epitopes on nativeEnvmolecules derived from Cw4 positive and negative viruses was determined by a monoclonal antibody-based enzyme-linked immunosorbent assay. Immunoprecipitation experiments were performed to investigate the presence of gp120/HLA Cw4 complexes. Neutralization assays determined the differences in susceptibility to neutralization between HLA Cw4 negative and positive viruses.Results and conclusions:The infectivity of primary HIV-1 X4 isolates and of TCLA viruses is increased upon viral incorporation of HLA Cw4 molecules. This effect is associated with changes in viral envelope proteins conformation including an enhanced expression of the V3 loop of gp120, and of epitopes that are exposed upon CD4 binding. The gp120 conformational changes are consistent with the formation of a multimolecular complex between HLA class I and gp120/160. HLA Cw4 incorporation is also associated to a lower susceptibility to antibody neutralization. These findings have important implications for understanding the immune response to cryptic and conformational epitopes of the viral envelope.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background:HIV-specific cytotoxic T lymphocytes (CTL) can restrict HIV replication in acute and chronic infection, but disease progression occurs in parallel with declining CTL activity. An understanding of why CTL fail to control HIV replication might reveal important mechanisms of disease progression and enhance prospects for developing effective CTL-based immunotherapies.Objectives:To investigate the functional integrity, T-cell repertoire diversity, and HIV reactivity of CD8 T lymphocytes in individuals with advanced HIV infection.Methods:Individuals were considered to have progressed to advanced HIV infection if their total T-cell count was <500×106cells/l on at least two successive clinic visits. CD8 T cells from these individuals were analyzed for CTL function, HIV reactivity and T-cell receptor (TCR) diversity by chromium release assays and reverse transcriptase polymerase chain reaction.Results:CD8 T cells from all individuals with advanced HIV infection proliferated and differentiated into functional CTLin vitro. Despite extremely low T-cell counts and previous AIDS-defining illnesses, six individuals had inducible anti-HIV CTL responses. In two additional cases, HIV-specific CTL activity became detectable following significant treatment-associated remission of T-cell lymphopenia. Assessment of TCR&bgr;V gene family representation and &bgr;V gene intrafamily diversity indicated CD8 T-cell repertoire diversity is maintained through advanced HIV infection.Conclusions:These data suggest that HIV-specific CTL activity can be selectively compromised while the functional and genetic integrity of the CD8 population as a whole remains intact. A substantial fraction of individuals retain inducible anti-HIV CTL activity through advanced HIV infection and, in at least some cases, effective treatment can restore HIV-specific CTL responses even at this late stage of disease.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Background:Approximately one quarter of patients with AIDS develop severe cognitive deficits called HIV-associated dementia complex. There is some controversy regarding the importance of viral load and distribution in mediating this neurologic disease.Objective:Brain HIV proviral and RNA loads were compared to define the molecular nature of HIV infection of the brain.Method:Neuropathologic examination was performed on brains from 10 autopsies of patients with AIDS that had short post-mortem intervals and no evidence of opportunistic infection. Viral DNA and RNA were extracted and quantified from multiple brain regions. These findings were compared with triple-label immunofluorescence for viral and cell markers.Results:Brains with histopathologic evidence of HIV encephalitis contained abundant HIV RNA and DNA. Regions without productive HIV infection showed minimal proviral load. By immunocytochemistry, only brain macrophages/microglia double labeled for viral proteins.Conclusions:HIV mediates a productive infection of brain macrophages/microglia. There was no evidence supporting the hypothesis of substantial neuronal or macroglial infection, or evidence of substantial proviral burden prior to the development of productive infection.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To assess the patterns of HIV phenotypic cross-resistance to protease inhibitors (PI) in patients experiencing viral load rebound on combination therapy including a PI.Methods:Phenotypic analysis of sensitivity to indinavir, nelfinavir, saquinavir, ritonavir and amprenavir was carried out using a single-cycle recombinant virus assay. Viral protease was sequenced by automated dideoxynucleotide chain termination.Results:Of the 108 patients studied, 68 had received indinavir, 50 ritonavir, 25 saquinavir and eight nelfinavir. The majority (71%) had received only one PI. The incidence of cross-resistance between indinavir, nelfinavir, ritonavir and saquinavir was high (60-90%). Cross-resistance to amprenavir was less frequent (37-40%). However there was some correlation between levels of sensitivity to amprenavir and indinavir (r2=0.34;P<0.01). Conversely, the correlation between levels of sensitivity to indinavir and saquinavir was poor (r2=0.25), particularly for patients who had not received saquinavir. The degree of cross-resistance correlated with the level of resistance and with the total number of mutations in the protease gene (P<0.05, chi square test) but could not be significantly correlated to any one particular mutation or combination of mutations. Mutation I84V was significantly associated with cross-resistance to amprenavir, with no mutations at codon 50 observed, while mutations associated with cross-resistance to saquinavir differed according to the treatment received.Conclusions:These results suggest that, although the total number of protease mutations correlates with the degree of cross-resistance, the specific mechanisms accounting for primary resistance and for cross-resistance may be different.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To define the effectiveness of chemoprophylaxis, outside of a clinical trial setting, in preventing tuberculosis among tuberculin-reactive and anergic HIV-infected drug users at high risk of developing active tuberculosis.Design:An observational cohort study.Setting:Methadone maintenance treatment program with on-site primary care.Participants:Current or former drug users enrolled in methadone treatment.Interventions:Annual skin testing for tuberculosis infection and anergy was performed, and eligible patients were offered daily isoniazid for 12 months and followed prospectively.Main outcome measure:The development of active tuberculosis.Results:A total of 155 persons commenced chemoprophylaxis. Among tuberculin reactors, tuberculosis rates were 0.51 and 2.07/100 person-years in those completing 12 months versus those not taking prophylaxis [rate ratio 0.25, 95% confidence interval (CI) 0.06-1.01]. Among anergic individuals, comparable rates were 0 and 1.44/100 person-years. Lower tuberculosis rates among completers were not attributable to differences in immune status between the treated and untreated groups.Conclusion:The completion of isoniazid chemoprophylaxis was associated with a marked reduction in tuberculosis risk among tuberculin reactors and anergic persons in this high-risk population. These data support aggressive efforts to provide a complete course of preventative therapy to HIV-infected tuberculin reactors, and lend weight to the findings of others that isoniazid can reduce the rate of tuberculosis in high-risk anergic HIV-infected persons.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objectives:It is important to assess the extent of bias when comparing the clinical efficacy of antiretroviral regimens in observational databases because, with the current lack of planned large trials, such analyses may represent the only means of assessing the risk of serious clinical events associated with new regimens. We aimed to compare the results from observational databases with those from randomized trials.Methods:Three treatment comparisons from randomized trials [Delta, AIDS Clinical Trials Group (ACTG) 175, Community Programs for ClinicalResearch onAIDS (CPCRA) 007 and ACTG 320] were mimicked in cohorts: (i) zidovudine monotherapy versus combination regimens of two nucleoside analogues; (ii) zidovudine combined with either didanosine or zalcitabine; and (iii) a dual combination versus a triple regimen including a protease inhibitor. Data for over 10000 patients from the French Hospital Database on HIV, the EuroSIDA study and the Swiss HIV cohort study were analysed for each of the comparisons. Progression to AIDS disease or death was analysed in Cox models, adjusting for baseline differences, and results compared with randomized trials.Results:For comparison (i) the adjusted relative risk estimates from cohorts were between 0.61 and 0.84, favouring combinations over monotherapy, compared with 0.57 to 0.63 for trials. For comparison (ii) relative risk estimates from cohorts ranged from 0.81 to 1.01 compared with 0.77 to 0.92 for trials. For comparison (iii), two of the cohorts showed similar results to the ACTG 320 trial but one indicated a higher risk of progression on triple therapy [relative risk 1.20, 95% confidence interval (CI) 1.01-1.44], in direct contrast to the trial result (relative risk 0.50, 95% CI 0.33-0.76).Conclusion:Serious biases can be present when comparing outcomes from the use of antiretroviral regimens in observational studies. However, such bias is not inevitable and careful interpretation of the results from several observational studies considered together is likely to be informative, guiding the design of new trials.

ISSN:0269-9370    

出版商:OVID    

年代:1999

数据来源: OVID