PubMed Health⌕ Search

Biomedical subjects

D D Richman

Publications and source records attributed to D D Richman.

At least 91 records · Page 5Linked to original sources
PubMed1997

Reduction of HIV-1 in blood and lymph nodes following potent antiretroviral therapy and the virologic correlates of treatment failure.

Potent antiretroviral therapy can reduce plasma HIV RNA levels below the threshold of detection for periods of a year or more. The magnitude of HIV RNA reduction in the lymphoid tissue in patients with suppression of HIV RNA levels in plasma beyond 6 months has not been determined. We evaluated levels of HIV RNA and DNA and characterized resistance mutations in blood and inguinal lymph node biopsies obtained from 10 HIV-infected subjects who received 36-52 weeks of indinavir (IDV)/zidovudine (ZDV)/lamivudine (3TC), IDV, or ZDV/3TC. After 1 year of therapy, viral RNA levels in LN of individuals remained detectable but were log10 = 4 lower than in subjects on the triple drug regimen with interruption of therapy or in those treated with ZDV/3TC alone, who had viral loads in their lymph nodes indistinguishable from those expected for untreated patients. In all cases viral DNA remained detectable in lymph nodes and peripheral blood mononuclear cells (PBMC). When plasma virus suppression was incomplete, lymph node and PBMC cultures were positive and drug resistance developed. These studies indicate that pronounced and sustained suppression of plasma viremia by a potent antiretroviral combination is associated with low HIV RNA levels in the lymph nodes 1 year after treatment. Conversely, the persistence of even modest levels of plasma virus after 1 year of treatment reflects ongoing viral replication, the emergence of drug resistance, and the maintenance of high burdens of virus in the lymph nodes.

Anti-HIV Agents↗
PubMed1997

Treatment with indinavir, zidovudine, and lamivudine in adults with human immunodeficiency virus infection and prior antiretroviral therapy.

BACKGROUND: The new protease inhibitors are potent inhibitors of the human immunodeficiency virus (HIV), and in combination with other antiretroviral drugs they may be able to cause profound and sustained suppression of HIV replication. METHODS: In this double-blind study, 97 HIV-infected patients who had received zidovudine treatment for at least 6 months and had 50 to 400 CD4 cells per cubic millimeter and at least 20,000 copies of HIV RNA per milliliter were randomly assigned to one of three treatments for up to 52 weeks: 800 mg of indinavir every eight hours; 200 mg of zidovudine every eight hours combined with 150 mg of lamivudine twice daily; or all three drugs. The patients were followed to monitor the occurrence of adverse events and changes in viral load and CD4 cell counts. RESULTS: The decrease in HIV RNA over the first 24 weeks was greater in the three-drug group than in the other groups (P<0.001 for each comparison). RNA levels decreased to less than 500 copies per milliliter at week 24 in 28 of 31 patients in the three-drug group (90 percent), 12 of 28 patients in the indinavir group (43 percent), and none of 30 patients in the zidovudine-lamivudine group. The increase in CD4 cell counts over the first 24 weeks was greater in the two groups receiving indinavir than in the zidovudine-lamivudine group (P< or =0.01 for each comparison). The changes in the viral load and the CD4 cell count persisted for up to 52 weeks. All the regimens were generally well tolerated. CONCLUSIONS: In most HIV-infected patients with prior antiretroviral therapy, the combination of indinavir, zidovudine, and lamivudine reduces levels of HIV RNA to less than 500 copies per milliliter for as long as one year.

Adult↗
PubMed1997

Synthesis and in vitro activity of long-chain 5'-O-[(alkoxycarbonyl)phosphinyl]-3'-azido-3'-deoxythymidines against wild-type and AZT- and foscarnet-resistant strains of HIV-1.

Lipophilic esters of 3'-azido-3'-deoxy-5'-O-(carboxyphosphinyl)thymidine (PFA-AZT) were synthesized and tested for antiretroviral activity in CD4+ HT4-6C cells infected with either wild-type HIV-1LAI, a PFA-resistant strain encoding a single-point mutation in reverse transcriptase (E89K), or an AZT-resistant clinical isolate (A018-post). Arbuzov condensation of 1-octadecyl, 1-eicosanyl, and 1-docosanyl chloroformate with trimethyl phosphite yielded the corresponding dimethyl long-chain alkyl triesters of PFA. Selective removal of one methyl group from the triesters with sodium iodide yielded monosodium salts, whereas treatment with bromotrimethylsilane cleaved both methyl groups while leaving the long-chain alkyl group intact. Neutralization of the resulting [(alkyloxy)carbonyl]phosphonic acids with 2 equiv of sodium methoxide afforded disodium salts of the phosphonic acid moiety. Similar chemistry was used to obtain the mono- and disodium salts of the cholesterol ester of PFA. Reaction of the triesters with phosphorous pentachloride, followed by coupling with AZT and O-demethylation with sodium iodide, afforded 3'-azido-3'-deoxy-5'-O-[[(1-octadecyloxy)carbonyl]phosphinyl ]thymidine (9a), 3'-azido-3'-deoxy-5'-O-[[(1-eicosanyloxy)carbonyl]phosphinyl ]thymidine (9b), 3'-azido-3'-deoxy-5'-O-[[(1-docosanyloxy)carbonyl]phosphinyl ]thymidine (9c), and 3'-azido-3'-deoxy-5'-O-[[(3 beta-cholest-5-enyloxy)carbonyl]phosphinyl]thymidine (9d). Concentrations of 9a-d found to inhibit replication of wild-type HIV-1LAI by 50% (EC50 values) as measured in a plaque reduction assay were in the 0.1-0.3 microM range as compared with 0.013 microM for AZT and 133 microM for PFA. The concentration at which toxicity was observed in 50% of the host cells (TC50 values) as measured by a visual grading scale of cellular morphology was 10 microM for 9a and 9d, 32 microM for 9b, and 320 microM for 9c. Thus, the TC50/EC50 ratio or selectivity index (SI) was 100 for 9a, 230 for 9b, and 1000 for 9c but only 33 for 9d, suggesting that the straight-chained fatty alcohol esters were more therapeutically selective. Similar TC50 and SI values were obtained for rapidly dividing CEM lymphoblasts as for HT4-6C cells. In assays against E89K, 9a-c had mean EC50 values of 0.13, 0.009, and 0.17 microM, whereas the EC50 of PFA was > 1000 microM and that of AZT was 0.009 microM; thus, E89K was highly resistant to PFA but not cross-resistant to either AZT or the lipophilic PFA-AZT conjugates. In viral replication assays against the A018C-post isolate, the mean EC50 values of 9a-c were 0.30, 0.53, and 0.77 microM as compared with 2.9 microM for AZT and 65 microM for PFA; thus, the virus recovered from a patient pretreated with AZT was not cross-resistant to either PFA or 9a-c. A notable feature of these results was that, in addition to being > 1000-fold more potent than PFA against the PFA-resistant mutant, the lipophilic PFA-AZT conjugates were more potent than PFA, as well as AZT, against AZT-resistant HIV-1.

Anti-HIV Agents↗
PubMed1997

Antiretroviral therapy for HIV infection in 1997. Updated recommendations of the International AIDS Society-USA panel.

OBJECTIVE: To provide current recommendations for antiretroviral therapy for human immunodeficiency virus (HIV) disease. PARTICIPANTS: The original International AIDS Society-USA 13-member panel representing international expertise in antiretroviral research and care of patients with HIV infection. EVIDENCE: The following were considered: Newly available clinical and basic science study results, including phase 3 controlled trials; clinical, virological, and immunologic end-point data; interim analyses of studies presented at national and international research conferences; studies of HIV pathophysiology; and expert opinions of panel members. Recommendations were limited to the drugs available in mid 1997. PROCESS: The full panel met on a regular basis (July 1996, September 1996, November 1996, January 1997, and April 1997) since the publication of its initial recommendations in mid 1996 to review new research reports and interim results. The panel discussed whether and how new information changed its initial recommendations. The recommendations contained herein were determined by group consensus. CONCLUSIONS: New data have provided a stronger rationale for earlier initiation of more aggressive therapy than previously recommended and reinforce the importance of careful selection of initial drug regimen for each patient for optimal long-term clinical benefit and adherence. The plasma viral load is a crucial element of clinical management for assessing prognosis and the effectiveness of therapy, and such testing must be done properly. Treatment failure is most readily indicated by a rising plasma HIV RNA level and should be confirmed prior to a change of treatment. Therapeutic approaches must be updated as new data, particularly on the long-term clinical effect of aggressive antiretroviral treatment, continue to emerge.

Anti-HIV Agents↗
PubMed1997

Phase I/II study of the toxicity, pharmacokinetics, and activity of the HIV protease inhibitor SC-52151.

SC-52151, an HIV-1 protease inhibitor, was developed as an ethanol-based elixir and subsequently as a self-emulsifying drug delivery system (SEDDS) to improve bioavailability. To evaluate formulation and treatment regimen effects, we conducted a four-arm, phase I/II study using the highest previously tested daily dose, 2250 mg. Forty-nine patients received the elixir or SEDDS at a dosage of 750 mg three times daily or 1125 mg twice daily for 14 days. One patient developed hypertriglyceridemia, and one had fever and dyspnea. The SEDDS formulation compared with the elixir resulted in a larger area under the concentration-time curve (AUC, p < 0.001), peak (Cmax, p = 0.041) and trough (Cmin, p = 0.025). Twice-daily administration compared with administration three times daily produced a higher cumulative AUC (p = 0.008). Both SEDDS regimens produced mean plasma concentrations above the 90% inhibitory concentration (IC90) for HIV. A mean decline of 0.03 log10 RNA copies (SEDDS) and an increase of 0.15 log10 (elixir) were observed. Although SC-52151 was well tolerated and the SEDDS formulation resulted in plasma concentrations above the IC90 for viral replication, no antiviral activity was produced.

Adult↗
PubMed1997

A new reporter cell line to monitor HIV infection and drug susceptibility in vitro.

Determination of HIV infectivity in vitro and its inhibition by antiretroviral drugs by monitoring reduction of production of p24 antigen is expensive and time consuming. Such assays also do not allow accurate quantitation of the number of infected cells over time. To develop a simple, rapid, and direct method for monitoring HIV infection, we generated a stable T-cell line (CEM) containing a plasmid encoding the green fluorescent protein (humanized S65T GFP) driven by the HIV-1 long terminal repeat. Clones were selected that displayed low constitutive background fluorescence, but a high level of GFP expression upon infection with HIV. HIV-1 infection induced a 100- to 1,000-fold increase in relative fluorescence of cells over 2 to 4 days as monitored by fluorescence microscopy, cytofluorimetry, and flow cytometry. Addition of inhibitors of reverse transcriptase, protease, and other targets at different multiplicities of infection permitted the accurate determination of drug susceptibility. This technique also permitted quantitation of infectivity of viral preparations by assessment of number of cells infected in the first round of infection. In conclusion, the CEM-GFP reporter cell line provides a simple, rapid, and direct method for monitoring HIV infectivity titers and antiretroviral drug susceptibility of syncytium-inducing strains.

Anti-HIV Agents↗
PubMed1997

Preferential replication of HIV-1 in the CD45RO memory cell subset of primary CD4 lymphocytes in vitro.

The ability of HIV-1 to establish an infection and replicate to high copy number in CD4 lymphocytes is dependent on both the activation state of the cell and virus-encoded regulatory proteins that modulate viral gene expression. To study these required virus-cell interactions, we have used an in vitro cell model of acute HIV infection of quiescent, primary CD4 lymphocytes and subsequent induction of T cell activation and virus replication by lectin or CD3 receptor cross-linking. Experiments were done to determine if the capacity of HIV to establish infection and complete replication was impacted by the maturational state of the CD4 cell target or the specific signal induction pathway engaged during activation. Primary CD4 cells were FACS-sorted into the major phenotypic subsets representative of memory (CD45RO) and naive (CD45RA) cells. Levels of virus replication were compared between infection with wild-type NL4-3 virus and an isogenic mutant containing a deletion in nef regulatory gene. PHA mitogen stimulation was compared with anti-CD3, with and without anti-CD28 costimulation, for induction of cell proliferation and virus replication. In both infected and uninfected cells, the RA cell subset exhibited significantly greater response to CD3/CD28 stimulation than did the RO cell subset. In contrast, the majority of virus replication occurred consistently in the RO cell subset. Deletion of HIV nef function caused a severe reduction in viral replication, especially in the RA naive cell subset after CD3 induction. PCR analysis of viral DNA formation, during infection of quiescent cells, demonstrated that the observed differences in HIV replication capacity between RO and RA cell subsets were not due to inherent differences in cell susceptibility to infection. Our results indicate that HIV replication is enhanced selectively in CD45RO memory phenotype cells through the probable contribution of specialized cellular factors which are produced during CD3-initiated signal transduction.

CD4-Positive T-Lymphocytes↗
PubMed1997

Alkoxy propane prodrugs of foscarnet: effect of alkyl chain length on in vitro antiviral activity in cells infected with HIV-1, HSV-1 and HCMV.

The identification of more effective and less toxic foscarnet (PFA) analogs for antiviral therapy would be useful. We recently synthesized 1-O-octadecyl-sn-glycero-3-phosphonoformic acid (ODG-PFA) and noted a 93-fold increase in its anti-HCMV activity relative to PFA. In addition, the antiviral activity of ODG-PFA in herpes simplex virus type-1 (HSV-1) and human immunodeficiency virus type-1 (HIV-1) infected cells was increased 40-fold relative to PFA (Hostetler et al., 1996. Antiviral Res. 31, 59). To evaluate structure-activity relationships further, we synthesized alkoxypropyl esters of foscarnet with varying alkyl chain lengths and degrees of saturation. These compounds were tested in vitro for activity and selectivity in comparison with PFA and ODG-PFA in cells infected with HCMV, HSV-1 or HIV-1. Antiviral activity was strongly dependent on chain length with alkyl ethers 14-18 carbon atoms long exhibiting the greatest antiviral activity against HCMV and HSV-1. In HIV-infected HT4-6C cells, optimal activity was observed at 18-22 carbon chain lengths. The antiviral activities of 1-octadecyloxypropane-3-PFA and 1-docosyloxypropane-3-PFA were 135- and 338-fold greater than that of PFA in HT4-6C cells infected with HIV-1. This also represents a 2.6-6-fold improvement in antiviral activity over ODG-PFA, the previously reported analog.

Antiviral Agents↗
PubMed1997

Immunostimulatory DNA sequences function as T helper-1-promoting adjuvants.

An adjuvant role for certain short bacterial immunostimulatory DNA sequences (ISSs) has recently been proposed on the basis of their ability to stimulate T helper-1 (Th1) responses in gene-vaccinated animals. We report here that noncoding, ISS-enriched plasmid DNAs or ISS oligonucleotides (ISS-ODNs) potently stimulate immune responses to coadministered antigens. The ISS-DNAs suppress IgE synthesis, but promote IgG and interferon-gamma (IFN-gamma) production. They furthermore initiate the production of IFN-gamma, IFN-alpha, IFN-beta, and interleukins 12 and 18, all of which foster Th1 responses and enhance cell-mediated immunity. Consideration should be given to adding noncoding DNA adjuvants to inactivated or subunit viral vaccines that, by themselves, provide only partial protection from infection.

Adjuvants, Immunologic↗
PubMed1997

A mutation in human immunodeficiency virus type 1 protease at position 88, located outside the active site, confers resistance to the hydroxyethylurea inhibitor SC-55389A.

The hydroxyethylurea human immunodeficiency virus type 1 (HIV-1) protease inhibitors SC-55389A and SC-52151 were used to select drug-resistant variants in vitro. One clinical HIV-1 strain (89-959) and one laboratory HIV-1 strain (LAI) were passaged in peripheral blood mononuclear cells or CEMT4 cells in the presence of SC-55389A. Resistant isolates from both strains consistently had a mutation to serine for asparagine at amino acid 88 (N88S) in the protease gene either alone or in combination with a change to phenylalanine at position 10. The N88S mutation, recreated by oligonucleotide-mediated site-directed mutagenesis in HXB2, was sufficient to confer resistance to SC-55389A. In contrast, SC-52151-resistant variants selected from the monocytotropic strain SF162 had multiple substitutions in the protease gene (I11V, M461, F53L, A71V, and N88D), and the N88D mutation, re-created by oligonucleotide-mediated site-directed mutagenesis in HXB2, did not confer resistance to SC-52151. The potencies of L735,524 and Ro31-8959 were not reduced when these compounds were assayed against variants with either the N88S or N88D substitution. Position 88 is in a helix that lies behind the substrate binding pocket and may indirectly influence inhibitor binding through interactions with the amino acid at position 31. The selected mutations were persistent in the viral populations after more than 20 passages in the absence of drugs. Passaging of virus first in SC-55389A alone and then in combination with SC-52151 resulted in the accumulation of more mutations in the protease gene (L10F, D35E, D37M, I47V, 154L, A71V, V82I, and S88D) and in the selection of a variant that was cross-resistant to multiple protease inhibitors. These results indicate that a mutation in the HIV-1 protease at a position that is located outside of the substrate binding pocket confers resistance to a protease inhibitor and that mutations in the protease gene accumulate with increasing selection pressure and can persist in the absence of selection pressure.

Amino Acid Sequence↗
PubMed1997

Standardized peripheral blood mononuclear cell culture assay for zidovudine susceptibility testing of clinical human immunodeficiency virus type 1 isolates: effect of reducing the numbers of replicates and concentrations.

Zidovudine susceptibility was assessed for 525 clinical human immunodeficiency virus type 1 isolates, before and after reducing the number of replicates and zidovudine concentrations in the standardized consensus peripheral blood mononuclear cell culture assay. We conclude that omitting the 0.001 microM concentration and using duplicate rather than triplicate wells are valid and cost-effective modifications of this expensive assay.

Anti-HIV Agents↗
PubMed1997

In vivo compartmentalization of human immunodeficiency virus: evidence from the examination of pol sequences from autopsy tissues.

High rates of mutation and replication of human immunodeficiency virus (HIV) allow for the continuous generation of diverse genetic variants in vivo. Selective pressures within the microenvironments of different anatomic compartments result in the emergence of dominant quasispecies which can be distinguished by their envelope sequences. It is not known whether comparable tissue-specific selective pressures lead to the independent evolution of pol sequences within different tissue compartments, nor is it known how differing rates of virus turnover in tissues might affect the pace of such evolution. These issues are of importance for the formulation of a model for the emergence of drug resistance in vivo and for a general understanding of virus trafficking and virus turnover. Regions of the HIV type 1 reverse transcriptase (RT) which carry the majority of the known resistance codons to RT inhibitors (700 nucleotides from each clone) were cloned and sequenced directly from autopsied brain, spleen, and lymph node specimens from four subjects who had received zidovudine therapy. Clones from proviral DNA (143) and from viral cDNA (14) were analyzed. In three of four subjects, a discordance in distribution of resistance codons was noted. Moreover, brain-derived sequences appeared to be phylogenetically distinct from spleen- and lymph node-derived sequences even after exclusion of resistance codons from analysis. In each case, evidence for differential immune selective pressure, based on comparison of inferred amino acid sequences corresponding to known major histocompatibility complex class I cytotoxic T-lymphocyte epitopes, was found. These observations support the concept of anatomically distinct, independently evolving quasispecies (virodemes).

Acquired Immunodeficiency Syndrome↗
PubMed1996

New strategies to combat HIV drug resistance.

Recent insights into HIV dynamics argue strongly for early intervention with antiretroviral combinations designed to block resistant mutations. By using more potent agents and taking advantage of drug selective pressure to force the emergence of strains with reduced evolutionary fitness, investigators are attempting to bring HIV replication to a halt. And in many cases, they appear to be succeeding.

Anti-HIV Agents↗
PubMed1996

Antiretroviral therapy for HIV infection in 1996. Recommendations of an international panel. International AIDS Society-USA.

OBJECTIVE: To provide clinical recommendations for antiretroviral therapy for human immunodeficiency virus (HIV) disease with currently (mid 1996) available drugs. When to start therapy, what to start with, when to change, and what to change to were addressed. PARTICIPANTS: A 13-member panel representing international expertise in antiretroviral research and HIV patient care was selected by the international AIDS Society-USA. EVIDENCE: Available clinical and basic science data, including phase 3 controlled trials, clinical endpoint data, virologic and immunologic endpoint data, interim analyses, studies of HIV pathophysiology, and expert opinions of panel members were considered. Recommendations were limited to drugs available in mid 1996. PROCESS: For each question posed, 1 or more member(s) reviewed and presented available data. Recommendations were determined by group consensus (January 1996); revisions as warranted by new data were incorporated by group consensus (February-May 1996). CONCLUSIONS: Recent data on HIV pathogenesis, methods to determine plasma HIV RNA, clinical trial data, and availability of new drugs point to the need for new approaches to treatment. Therapy is recommended based on CD4+ cell count, plasma HIV RNA level, or clinical status. Preferred initial drug regimens include nucleoside combinations; at present protease inhibitors are probably best reserved for patients at higher progression risk. For treatment failure or drug intolerance, subsequent regimen considerations include reasons for changing therapy, available drug options, disease stage, underlying conditions, and concomitant medication(s). Therapy for primary (acute) infection, high-risk exposures to HIV, and maternal-to-fetal transmission are also addressed. Therapeutic approaches need to be updated as new data continue to emerge.

Antiviral Agents↗