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PubMed1996

Quantitative structure-activity relationship studies on anti-HIV-1 TIBO derivatives as inhibitors of viral reverse transcriptase.

The anti-human-immunodeficiency-virus (HIV-1) activity of the derivatives of 4,5,6,7-tetrahydro-5-methylimidazo [4,5,1-jk] [1,4] benzodiazepin-2(1H)-one (TIBO) that have been found to elicit their action through the allosteric inhibition of the enzyme viral reverse transcriptase (VRT) is analysed in relation to the physicochemical properties of the molecules. Significant correlations are obtained between the activity and the hydrophobic constant and some dummy parameters of substituents. Based on these findings, the mechanism of action of these anti-HIV drugs is discussed.

Anti-HIV Agents↗
PubMed2000

Identification and management of tuberculosis.

Although the resurgence of tuberculosis in the early 1990s has largely been controlled, the risk of contracting this disease remains high in homeless persons, recent immigrants and persons infected with the human immunodeficiency virus (HIV). Purified protein derivative testing should be targeted at these groups and at persons with known or suspected exposure to active tuberculosis. Most patients with latent tuberculosis are treated with isoniazid administered daily for nine months. In patients with active tuberculosis, the initial regimen should include four drugs for at least two months, with subsequent therapy determined by mycobacterial sensitivities and clinical response. To avoid harmful drug interactions, regimens that do not contain rifampin may be employed in HIV-infected patients who are taking protease inhibitors or nonnucleoside reverse transcriptase inhibitors. To maximize compliance and minimize the emergence of mycobacterial drug resistance, family physicians should consider using directly observed therapy in all patients with tuberculosis.

Adult↗
PubMed2001

[Nephrolithiasis in a HIV infected patient treated with indinavir].

Protease inhibitors together with reverse transcriptase inhibitors are used in antiretroviral treatment. Indinavir, precipitating in renal tubules, quite often can cause nephrolithiasis. The case of a HIV infected patient with renal colic probably caused by indinavir, diagnostic and therapeutic options in such cases are described in the paper.

Adult↗
PubMed1992

Rifamycins as inhibitors of retroviral reverse transcriptase from M-MuLV, RAV-2, and HIV-1.

29 Rifamycins were tested for inhibition of Reverse Transcriptase (RT) as potential anti HIV drugs. Two purified commercial enzymes from M-MuLV and RAV-2 were used. Anti-RT activity was also measured on a crude lysate of HIV-1. The results show that some derivatives have interesting levels of activity on isolated M-MuLV and RAV-2 RTs, while they are less active on the RT in the crude HIV-1 lysate. The active derivatives include oximes and hydrazones, alkylaminoderivatives, open ansa-chain derivatives and derivatives carrying a modified nucleoside.

HIV Reverse Transcriptase↗
PubMed1992

Quinolinehydrazones as inhibitors of retroviral reverse transcriptase.

The inhibitory activity of a series of 2- and 4-quinolinehydrazones on retroviral reverse transcriptase has been studied on enzymes from M-MuLV, RAV-2, and on a crude lysate of HIV-1, assuming the first two enzymes as potential models of the third. The highest activity is mainly found in lipophilic, water soluble 4-quinolinehydrazones. The inhibitory activity of these compounds decreases in changing from the M-MuLV to the RAV-2, and HIV-1 enzymes, in this order.

Cell Survival↗
PubMed2004

Developments in HIV treatments: strategies for success.

The current primary goal of therapy for HIV-1 infection is suppression of viral replication to below detectable levels (less than 50 copies/mL). The most important challenge facing current HIV-1 research is designing agents that prevent the emergence of or overcome drug-resistant HIV-1 variants. Shortcomings of antiretroviral therapy have sparked interest in immunologic enhancement through vaccines and immunomodulators, specifically antigen stimulation, induction of HIV-1 specific memory and cytotoxic T-cell responses, and activation of resting CD4+ cells within latent HIV-1 reservoirs. New classes of antiretroviral agents include entry inhibitors and nucleotide reverse transcriptase inhibitors. This article discusses the status of successful HIV treatment strategies, including new treatment practices, antiretroviral agents, and immune-enhancing agents.

Anti-HIV Agents↗
PubMedDate not supplied

HIV viral load quantification, HIV resistance, and antiretroviral therapy.

We are moving rapidly beyond a "black box" understanding of the pathogenesis of HIV. The sites of virus replication, the molecular regulation of virus production in the host, and the dynamics between productive virus infection and immunological and clinical events are areas of intense study using powerful new tools. The quantitation of virus load and genetic characterization of replicating virus has important implications for the development and evaluation of drugs and treatment strategies for HIV. As new compounds are introduced, their ability to reduce virus load in vivo has become a primary consideration in the decision to initiate large efficacy trials and may soon be used, in combination with other markers, in the licensing of new agents. In parallel, rapid molecular evaluation of virus from patients, targeting those who break through drug-induced suppression, provides an explanation for the failure of drugs to sustain an effect on virus load. This approach has compressed the process of drug evaluation and set the stage for the evaluation of complex combinations and sequences of drugs to maintain suppression of virus and prevent the development of drug resistance. The most controversial question for the next few years is whether the measurement of virus load or detection of drug resistance can be incorporated into the practice of medicine and the management of individual patients. There is evidence that changes in virus load are the most proximate markers of drug response and that detection of resistance mutations can predict clinical and immunological decline. However, the window of time between a change in load or the development of drug resistance and a decline in CD4 cells is relatively short. With dideoxynucleoside therapies, a CD4 cell decline follows a rise in virus load or development of resistance within 3-6 months. In early studies with protease inhibitors and nonnucleoside reverse transcriptase inhibitors, the development of resistance and a return to baseline of virus load may occur within 2-3 months, mirrored by a fall in CD4 cells. The challenge to investigators is how to best use these new tools to determine whether changes or additions in therapy, initiated on the basis of virological measurements, result in more effective management of disease.

Antiviral Agents↗
PubMed1998

Prevention and treatment of tuberculosis among patients infected with human immunodeficiency virus: principles of therapy and revised recommendations. Centers for Disease Control and Prevention.

These guidelines update previous CDC recommendations for the diagnosis, treatment, and prevention of tuberculosis (TB) among adults and children coinfected with human immunodeficiency virus (HIV) in the United States. The most notable changes in these guidelines reflect both the findings of clinical trials that evaluated new drug regimens for treating and preventing TB among HIV-infected persons and recent advances in the use of antiretroviral therapy. In September 1997, when CDC convened a meeting of expert consultants to discuss current information about HIV-related TB, special emphasis was given to issues related to coadministration of TB therapy and antiretroviral therapy and how to translate this information into management guidelines. Thus, these guidelines are based on the following scientific principles: * Early diagnosis and effective treatment of TB among HIV-infected patients are critical for curing TB, minimizing the negative effects of TB on the course of HIV, and interrupting the transmission of Mycobacterium tuberculosis to other persons in the community. * All HIV-infected persons at risk for infection with M. tubercu losis must be carefully evaluated and, if indicated, administered therapy to prevent the progression of latent infection to active TB disease and avoid the complications associated with HIV-related TB. * All HIV-infected patients undergoing treatment for TB should be evaluated for antiretroviral therapy, because most patients with HIV-related TB are candidates for concurrent administration of antituberculosis and antiretroviral drug therapies. However, the use of rifampin with protease inhibitors or nonnucleoside reverse transcriptase inhibitors is contraindicated. Ideally, the management of TB among HIV-infected patients taking antiretroviral drugs requires a) directly observed therapy, b) availability of experienced and coordinated TB/HIV care givers, and in most situations, c) use of a TB treatment regimen that includes rifabutin instead of rifampin. Because alternatives to the use of rifampin for antituberculosis treatment are now available, the previously recommended practice of stopping protease inhibitor therapy to allow the use of rifampin for TB treatment is no longer recommended for patients with HIV-related TB. The use of rifabutin-containing antituberculosis regimens should always include an assessment of the patient's response to treatment to decide the appropriate duration of therapy (i.e., 6 months or 9 months). Physicians and patients also should be aware that paradoxical reactions might occur during the course of TB treatment when antiretroviral therapy restores immune function. Adding to CDC's current recommendations for administering isoniazid preventive therapy to HIV-infected persons with positive tuberculin skin tests and to HIV-infected persons who were exposed to patients with infectious TB, this report also describes in detail the use of new shortcourse (i.e., 2 months) multidrug regimens (e.g., a rifamycin, such as rifampin or rifabutin, combined with pyrazinamide) to prevent TB in persons with HIV infection. A continuing education component for U.S. physicians and nurses is included.

AIDS-Related Opportunistic Infections↗
PubMed2001

High prevalence of genotypic and phenotypic HIV-1 drug-resistant strains among patients receiving antiretroviral therapy in Abidjan, Côte d'Ivoire.

To describe prevalence of antiretroviral (ARV) drug-resistant HIV-1 strains among patients with a history of earlier treatment with ARV drugs in Abidjan, Côte d'Ivoire, we determined mutations that confer HIV-1 ARV drug resistance by sequencing the viral reverse-transcriptase and protease genes derived from plasma viral RNA of 68 individuals consecutively enrolled in the Joint United Nations Program on AIDS Drug Access Initiative (UNAIDS-DAI) with a history of earlier ARV drug treatment in Abidjan between August 1998 and April 1999. Phenotypic ARV drug resistance was assessed using a recombinant virus assay. Primary mutations associated with ARV drug resistance to at least one of the reverse-transcriptase inhibitors or protease inhibitors were detected in 39 (57.4%) of the 68 patients. The prevalence of mutations associated with resistance to ARV drugs was: 29 (42.6%) to zidovudine, 10 (14.7%) to lamivudine, one (1.5%) to didanosine, one K103N mutation (associated with resistance to delavirdine, nevirapine, and efavirenz), one Y181C mutation (associated with resistance to delavirdine and nevirapine), two to both indinavir (M46I/L and V82A) and saquinavir (G48V and L90M), and one each to ritonavir (V82A) and nelfinavir (D30N). Phenotypic resistance to at least one nucleoside reverse transcriptase inhibitor (RTI) was seen in 25 (39.7%) patients, to nonnucleoside RTIs in 5 (8%) patients, and to protease inhibitors in 4 (6%) patients. The high prevalence we observed in this study may limit in future the effectiveness of ARV programs in the Côte d'Ivoire.

Anti-HIV Agents↗
PubMed2000

Determination of twelve antiretroviral agents in human plasma sample using reversed-phase high-performance liquid chromatography.

A new high-performance liquid chromatography (HPLC) with UV detection assay was developed for the simultaneous determination of protease inhibitors (PIs), nucleoside and non-nucleoside reverse transcriptase inhibitors (NRTIs, NNRTIs) using a single 1-ml plasma samples. A solid-liquid extraction procedure without internal standard was coupled with two separate reversed-phase HPLC systems; one for the determination of amprenavir, efavirenz, indinavir, nelfinavir, ritonavir, saquinavir (run time=32 min) and one for the determination of abacavir, didanosine, lamivudine, stavudine, nevirapine, zidovudine (run time=40 min). The first requires a mobile phase containing sodium phosphate buffer+ion pair-acetonitrile (50:50, v/v) through a C18 Symmetry column (250x4.6 mm I.D., 5 microm particle size), using variable wavelengths (241, 254 and 261 nm). The second system requires three mobile phases (potassium phosphate buffer+ion pair-acetonitrile) for different elution through a C18 Symmetry Shield column (250x4.6 mm I.D., 5 microm), using a single wavelength (260 nm). Peak-areas are linear; correlation coefficients are better than 0.998 for all compounds, with both inter- and intra-day relative standard deviations lower than 12%. Extraction recoveries are higher than 93% for PIs and NNRTIs and higher than 70% for NRTIs. The method is specific and sensitive and was used to determine trough and peak levels of antiretroviral drugs in HIV infected patients under various combinations of RTIs and PIs.

Anti-HIV Agents↗
PubMedDate not supplied

Incidence of adipose tissue alterations in first-line antiretroviral therapy: the LipoICoNa Study.

BACKGROUND: Adipose tissue alterations (ATAs) are a frequent untoward effect of antiretroviral therapy, the causes of which remain incompletely explained. OBJECTIVES: To assess the incidence of ATAs and to identify the associated risk factors in patients infected with human immunodeficiency virus type 1 starting their first-line antiretroviral treatment. METHODS: In a multicenter investigation designed to study issues related to the treatment of patients starting antiretroviral therapy, physicians were requested to assess the presence of ATAs at enrollment and every 6 months thereafter. The ATAs were considered altogether and grouped as fat loss (lipoatrophy), adipose tissue accumulation (lipohypertrophy), and combined forms. RESULTS: A total of 655 patients were followed up for a median of 86 weeks; 128 patients (19.6%) were diagnosed as having at least 1 morphologic alteration during the study. Female gender and positivity for hepatitis C virus were independently linked to an increased risk of developing morphologic alterations. Age was another independent correlate of risk of developing ATAs. To have been infected through drug injection was a correlate of reduced risk of ATAs. Stavudine exposure was predictive at borderline statistical significance of lipoatrophy (but not of the other forms), and indinavir exposure was associated with a significantly higher risk of developing combined forms. Patients who started therapy with 2 nucleoside reverse transcriptase inhibitors and subsequently added a protease inhibitor during the follow-up had a significantly higher risk of having ATAs compared with patients who continued taking 2 nucleoside reverse transcriptase inhibitors up to the end of follow-up. CONCLUSIONS: Different types of ATAs might derive from distinct pathways and multifactorial causes. Adipose tissue alterations are a frequent and relatively early finding during first-line antiretroviral therapy.

Adipose Tissue↗
PubMed2001

[Therapeutic aspects of HIV/AIDS infected patients and evaluation of therapeutic protocols].

The first HIV-infected patients were treated in 1986, however, at that time medicines inhibiting HIV replication were not available. Solely the complications of AIDS and opportunistic infections could be treated. The HIV replication inhibition capacity of antiretroviral nucleoside and ribavirin were tested in Hungary in 1987, an early date even in international practice. The first nucleoside reverse transcriptase inhibitor (NRTI), azidothymidine, presently called zidovudine (ZDV), was introduced in 1989. By giving patients the appropriate dosage of this, the progression of the disease could be delayed by approximately 6 months to one year. In 1991, the application of two new NRTI was commenced, namely zalcitabine (DDC) and didanosine (DDI). These medicines were applied partly in case of ZDV intolerance and as a part of the sequential monotherapy. In 1994 and 1995 two new NRTI's were introduce, namely stavudine (d4T) and lamivudine (3 TC). At that same time, to obtain a more effective replication inhibition method, a double NRTI combination became part of the therapeutic protocol. The year 1996 resulted in significant changes. At the beginning of the year, two compounds belonging to two new therapeutic procedures. These are saquinavir (SQV) and delavirdine (DLV) belonging to the groups of protease inhibitors and non-nucleoside reverse transcriptase, respectively. The so-called virus cocktails and the effective active antiretroviral therapy (HAART) were applied and, later, to monitor the efficiency of the treatment, the opportunity was provided to measure the copy number of HIV-RNS. The treatment of the HIV disease entails a number of unanswered questions. The maximum result that can be achieved by using today's therapeutic methods is to prolong that particular phase of the HIV disease, which secures the patient a fairly good quality of life. The new combination of the antiretroviral compounds produced by the pharmaceutical industry provides better changes to prolong said period by years, sometimes decades. However, the real solutions to the problem are only theoretically known treatment procedures (gene therapy, cytokins) today.

Acquired Immunodeficiency Syndrome↗
PubMed1997

SRR-SB3, a disulfide-containing macrolide that inhibits a late stage of the replicative cycle of human immunodeficiency virus.

From a series of macrocyclic diamides possessing the disulfide linkage, only SRR-SB3, a compound that complexes with zinc, was found to inhibit human immunodeficiency virus type 1 (HIV-1; strain IIIB) replication at a concentration of 1.8 to 6.5 micrograms/ml in MT-4, CEM, and peripheral blood mononuclear cells. SRR-SB3 was toxic to MT-4 cells at a concentration of 15.9 micrograms/ml, resulting in a selectivity index of 9 in these cells. This macrolide was also effective against various other HIV-1 strains, including clinical isolates and HIV-1 strains resistant to protease inhibitors and nucleoside and nonnucleoside reverse transcriptase inhibitors. It was also active against various HIV-2 strains, simian immunodeficiency virus (strain MAC251), and Moloney murine sarcoma virus, but not against viruses other than retroviruses. In addition, the compound was found to inhibit chronic HIV-1 infections in vitro. The compound in combination with other antiviral agents, such as zidovudine, zalcitabine, and stavudine, showed an effect that was between additive and synergistic. Time-of-addition experiments indicated that SRR-SB3 acts at a late stage of the HIV-1 replicative cycle.

Animals↗
PubMed2007

Radiosensitization effect of zidovudine on human malignant glioma cells.

Telomeres are shortened with each cell division and play an important role in maintaining chromosomal integrity and function. Telomerase, responsible for telomere synthesis, is activated in 90% of human tumor cells but seldom in normal somatic cells. Zidovudine (AZT) is a reverse transcriptase inhibitor. In this study, we have investigated the effects of gamma-radiation in combination with AZT on telomerase activity (TA), telomere length, DNA single-strand breaks (SSBs), DNA double-strand breaks (DSBs), and the changes in radiosensitivity of human malignant glioma cell line U251. The results showed that the TA was suppressed by AZT but enhanced by irradiation, resulting in a deceleration of restored rate of shortened telomere, decreased repair rate of DNA strand breaks, and increased radiosensitivity of U251 cells. Our results suggested that telomerase activity and telomere length may serve as markers for estimating the efficacy of cancer radiotherapy and reverse transcriptase inhibitors, such as AZT, may be used clinically as a new radiosensitizer in cancer radiotherapy.

Cell Line, Tumor↗
PubMed1995

Pol gene quasispecies of human immunodeficiency virus: mutations associated with drug resistance in virus from patients undergoing no drug therapy.

The nucleotide sequences of two pol gene regions (codons 41 to 108 and 181 to 219 of reverse transcriptase) of 60 human immunodeficiency virus type 1 genomes obtained directly from primary lymphocytes from infected individuals are reported. In addition, the mutant spectra of several quasispecies have been sampled by repetitive sequencing of molecular clones representing the same pol genomic regions. Average mutation frequencies ranged from 1.6 x 10(-2) to 3.4 x 10(-2) substitutions per nucleotide for independent samples (relative to their consensus nucleotide sequence) and from 3.6 x 10(-3) to 1.1 x 10(-2) substitutions per nucleotide for individual quasispecies distributions. Several mutations leading to amino acid substitutions related to loss of sensitivity to reverse transcriptase inhibitors have been identified in samples from patients not subjected to antiretroviral therapy. Mutation frequencies in the codons previously identified as involved in resistance to reverse transcriptase inhibitors were very similar to the average mutation frequencies in the pol region analyzed. Thus, the finding of mutations related to drug resistance (even in the absence of positive selection by the corresponding drugs) is the expected consequence of the statistical distribution of mutations along the pol gene. The presence of such critical amino acid replacements in human immunodeficiency virus type 1 populations underscores the importance of viral quasispecies as reservoirs of phenotypic virus variants and has a number of implications for AIDS control.

Amino Acid Sequence↗
PubMed2002

Comparison of virtual phenotype and HIV-SEQ program (Stanford) interpretation for predicting drug resistance of HIV strains.

OBJECTIVE: Drug resistant HIV strains can be identified by genotypic analysis. The prediction of resistance from the HIV pol sequence, however, requires expert interpretation which is currently provided by various interpretation programs. In the present study, the comparability of two of these programs was investigated. METHODS: One hundred and six HIV sequences obtained from patient samples were subjected to interpretation by the Stanford HIV-SEQ program (http://hivdb.stanford.edu) and, in parallel, by virtual phenotype analysis (VircoNET). RESULTS: The overall concordance between the two assays was high with respect to nonnucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors. Highly discrepant results were obtained from 22 samples (1.5% of all comparisons), and these discrepancies were significantly associated with the interpretation of nucleoside reverse transcriptase inhibitors (NRTIs) (P < 0.01), especially regarding resistance to zalcitabine (ddC), didanosine (ddI) and abacavir (ABC). Nearly all of these discrepant samples showed a sensitive virtual phenotype. Mutations at codons 69 and 74 were associated with a discrepant interpretation for ddC. CONCLUSIONS: The prediction of resistance to certain NRTIs from a given HIV sequence may be contradictory and requires further investigation.

Anti-HIV Agents↗
PubMed2000

Genotypic and phenotypic nevirapine resistance correlates with virological failure during salvage therapy including abacavir and nevirapine.

OBJECTIVE: To study the development of resistance during 8 weeks of salvage therapy with abacavir and nevirapine in combination with other reverse transcriptase inhibitors (RTIs) and protease inhibitors (PIs). METHODS: Samples obtained at baseline and after 8 weeks of therapy from 16 heavily pretreated patients were analysed for genotypic and phenotypic resistance. Genotypic resistance was analysed in cell-associated DNA and plasma HIV-RNA using direct sequencing. Phenotypic resistance was analysed in a PBMC-based assay and in a recombinant virus assay. Plasma viral load was measured at baseline and after 2, 4 and 8 weeks of therapy. RESULTS: The majority of patients was genotypically and phenotypically resistant to lamivudine, abacavir, zidovudine and PIs, whereas 50% of the patients showed resistance to nevirapine at baseline in at least one of the methods used. After 8 weeks of salvage therapy, no additional development of resistance against nucleoside reverse transcriptase inhibitors and PIs could be detected. However, the amount of patients resistant to nevirapine increased to 83%. When the patients were divided into two groups according to baseline resistance against nevirapine, a significantly higher transient reduction in viral load was observed in patients with nevirapine-sensitive HIV at baseline compared to patients with resistant HIV at baseline. CONCLUSION: The transient effect of salvage therapy including abacavir and nevirapine was due to the effect of nevirapine. The lack of effect of abacavir was most likely due to cross-resistance between abacavir and lamivudine/zidovudine used in previous treatment.

Anti-HIV Agents↗
PubMed2000

Effectiveness of antiretroviral therapy initiated before the age of 2 months in infants vertically infected with human immunodeficiency virus type 1.

UNLABELLED: The effectiveness and tolerance of antiretroviral therapy with a combination of three reverse transcriptase inhibitors starting at the time of diagnosis (before 2 months of age) was evaluated in four infants with vertically acquired HIV-1 infection. Plasma HIV-1 RNA levels ranged from 230,000 to 1,000,000 copies/ml before onset of triple therapy and fell below 50 copies/ml at 12 to 33 weeks of life in three of the infants. These three children, currently aged 158, 105 and 72 weeks, are asymptomatic, have normal lymphocyte subsets and no hypergammaglobulinaemia. Two children experienced a profound reduction in the amount of proviral DNA detected in blood and have become HIV-1 seronegative, although one of them has had HIV-1 RNA detectable on a single occasion at 114 weeks of life (303 copies/ml). Transient interruption of therapy resulted in a rapid but reversible increase in HIV-1 RNA levels in the third child and was associated with the production of HIV-specific antibodies. The fourth child whose parents were not compliant to treatment and follow-up had a poor virological response. CONCLUSION: Early treatment of vertically acquired human immunodeficiency virus type 1 infection with three reverse transcriptase inhibitors is well tolerated and can result in such suppression of viral replication that specific antibodies are not produced, that proviral DNA falls to the lower limit of quantitation in blood and that all clinical and immunological manifestations of infection are avoided. Parental adhesion is crucial to the effectiveness of therapy.

Anti-HIV Agents↗