The blocking of kappa-opioid receptor reverses the changes in dorsolateral striatum dopamine dynamics during the amphetamine sensitization.

Kappa-opioid receptors (KOR) control dopamine (DA) levels in the striatum and contribute significantly to the progression of drug addiction. Repeated exposure to psychostimulants has been associated with up-regulated KOR activity and increased DA levels in dorsal striatum. However, it has not been tested if both processes are linked. In this work, we studied if a mechanism mediated by KOR is contributing to the increase in DA levels in the dorsolateral striatum (DLS) after amphetamine (AMPH) sensitization. The AMPH sensitization was assessed after single or repeated once-a-day AMPH injections (1 mg/kg). Only repeated AMPH exposure produced a significant locomotor sensitization. No-net flux microdialysis was used to assess basal DA dialysate, DA extracellular concentration (Cext ), and DA uptake in DLS of anesthetized rats. The role of KOR on DA dynamics in DLS was evaluated by local perfusion (250 µM) and systemic administration (10 mg/kg) of the KOR antagonist nor-binaltorphimine. A significant decrease in DA Cext is observed in the DLS after an AMPH challenge in rats exposed to a single dose of AMPH. The decrease in DA Cext was associated with both a decreased basal DA dialysate and an increased DA uptake. Conversely, the expression of AMPH sensitization was accompanied by a significant increase in DA Cext associated with an increased basal DA dialysate and an attenuation in DA uptake. Both local and systemic administration of nor-binaltorphimine reversed changes in DLS after AMPH pre-treatment. These findings indicate that endogenous KOR system tunes DLS DA dynamics during the progression to AMPH sensitization.

Differential evolution of cell-associated virus in blood and genital tract of HIV-infected females undergoing HAART.

PBMC and vaginal cell (VC) viruses were studied from 5 HIV-infected females for the presence of drug-resistance and non-drug resistance associated mutations. A 1318-bp fragment of polymerase gene was amplified from PBMC and VC proviral DNA. Four of the 5 PBMC viruses exhibited drug resistance-associated mutations in reverse transcriptase and protease genes, whereas only 2 VC viruses contained drug resistance-associated mutations. However, all 5 females showed non-drug resistance-associated mutations both in PBMC and VC virus suggesting continuous evolution of the virus in these compartments. The emergence of drug resistance was slower in PBMC and VC viruses than that observed in the cell-free plasma (P) and vaginal secretion (VS) viruses. Phylogenetic analysis revealed that VC virus was closer to PBMC virus than either cell-free viruses (P and VS) suggesting comparable evolution among cell-associated viruses.

Influence of CD4+ T cell counts on viral evolution in HIV-infected individuals undergoing suppressive HAART.

We analyzed the viral C2-V4 envelope diversity, glycosylation patterns, and dS/dN ratios of plasma HIV-1 in an attempt to better understand the complex interaction between viral quasispecies and the host-selective pressures pre- and post-HAART. Phylogenetic analysis of the envelope gene of five patients revealed monophyletic clustering in patients with higher CD4+ T cell counts and sequence intermingling in those with lower CD4+ T cells in relation to the stage of HAART. Our analyses also showed clear shifts in N-linked glycosylation patterns in patients with higher CD4+ T cells, suggesting possible distinct immunological pressures pre- and post-HAART. The relative preponderance of synonymous/nonsynonymous changes in the envelope region suggested a positive selection in patients with higher CD4+ T cells, whereas lack of evidence for positive selection was found in the patients with lower CD4+ T cells. An exception to the last analysis occurred in the only patient who reached complete viral suppression, maybe due to drug pressure exerted over the pol gene that may obscure the immune pressure/selection at the envelope in this analysis. All these indications may suggest that even when HAART generates viral suppression, quasispecies evolve in the envelope gene probably resulting from host-selective pressure.

Compartmentalization of drug resistance-associated mutations in a treatment-naive HIV-infected female.

Development of a drug-resistant variant of HIV-1 has been one of the major concerns contributing to the transmission of the virus. A 40-year-old woman presented to the clinic with micosis and oral candidiasis. The subject was referred for HIV-1 diagnosis. Subsequent investigations revealed a very low CD4 T cell count (48 cell/microl blood) and high plasma HIV-1 RNA load (4.33 x 10(5) copy/ml). A 1.3-kb pol fragment was sequenced in virus collected from plasma and the vaginal compartment. Plasma virus had no mutation in reverse transcriptase and one mutation in protease (L63P). On the other hand vaginal virus contained L63P and M184V mutations in protease and reverse transcriptase, respectively. These mutations were accompanied by several other mutations in previously identified CTL epitopic regions of the two genes. In the absence of antiretroviral treatment, a drug-resistant mutant was thought to develop because of immune pressure. This is the first report describing the role of immune pressure in the development of a drug-resistant virus.

Differential virus evolution in blood and genital tract of HIV-infected females: evidence for the involvement of drug and non-drug resistance-associated mutations.

There is increasing evidence that male or female genital tract represent a distinct replication compartment for human immunodeficiency virus type 1 (HIV-1) and that such compartments may serve as a virus reservoir. Forty-four paired plasma and vaginal samples from HIV-infected females undergoing HAART were collected to examine the viral responses to antiretroviral therapy and to assess the possible role of the vaginal tract as a reservoir for drug-resistant variants. Twenty-one females had detectable viral RNA both in plasma and vaginal fluid, whereas 14 females had detectable virus only in plasma. Twelve paired samples were used to analyze HIV-1 pol sequences for the presence of drug resistance-associated mutations. Nine of the twelve paired samples exhibited discordant drug resistance mutation patterns. The other three females showed identical drug resistance-associated mutations. However, further examination of protease and RT showed numerous non-drug-associated mutations that corresponded to predefined CTL epitopes. These non-drug-associated mutations were different between plasma and vaginal viruses, suggesting that evolution of HIV-1 was independent in these two compartments.

The NEAT study: a 48-week open-label study to compare the antiviral efficacy and safety of GW433908 versus nelfinavir in antiretroviral therapy-naive HIV-1-infected patients.

OBJECTIVE: To compare the efficacy, durability, and tolerability of GW433908 (908), 1400 mg twice-daily (BID), with nelfinavir (NFV), 1250 mg BID. METHODS: This was an international, multicenter, randomized, open-label study (NEAT) in antiretroviral therapy (ART)-naive HIV-infected adults with plasma HIV-1 RNA (vRNA) at screening > or =5000 copies/mL (c/mL). Patients were randomly assigned to 908 or NFV (2:1) for a minimum of 48 weeks, with a background of abacavir (ABC) and lamivudine (3TC). RESULTS: A total of 166 patients received randomized treatment with 908 BID and 83 received NFV BID. The population was diverse with regard to race and gender (76% Hispanics and blacks, 31% female) and had advanced HIV disease at screening (45% had vRNA >100,000 c/mL, 48% had CD4 cell counts <200 cells/mm3, 20% had a history of Centers for Disease Control class C events). After 48 weeks of study by an intention-to-treat rebound or discontinuation = failure analysis, a greater proportion of patients in the 908 BID group (66%) than the NFV BID group (51%) achieved vRNA <400 c/mL. Furthermore, more patients with screening vRNA >100,000 c/mL (67 vs. 35%) or CD4 <50 cells/mm3 (48 vs. 24%) achieved undetectable viral loads taking 908 BID compared with NFV BID, respectively. Favorable immunologic responses were observed for both groups. Diarrhea, which was more common in the NFV BID group (18 vs. 5%), was the only drug-related grade 2-4 adverse event with a significant difference (P = 0.002) in incidence between groups. CONCLUSION: Administration of 908 BID resulted in a potent and sustained antiretroviral response, notably in ART-naive patients with advanced HIV disease. GW433908 was generally well tolerated and provides a convenient dosing option without food or fluid restrictions.

Lamivudine 300 mg QD versus continued lamivudine 150 mg BID with stavudine and a protease inhibitor in suppressed patients.

PURPOSE: To compare the efficacy (sustained virologic suppression) and safety/tolerability of a switch to lamivudine 300 mg once daily (QD) versus continued lamivudine 150 mg twice daily (BID) in virologically suppressed patients (HIV-1 RNA <400 copies/mL for > or =3 months) on stable (> or =6 months) therapy with lamivudine 150 mg BID plus stavudine and either indinavir or nelfinavir. METHOD: Eighty-nine suppressed patients > or =18 years old with CD4 counts >50 cells/mm(3) were enrolled in this phase II, open-label, multicenter, randomized, stratified (by pretrial protease inhibitor [PI]), parallel-group clinical trial. Eighty-one patients received either lamivudine 300 mg QD (n = 39) or 150 mg BID (n = 42) with their pretrial stavudine/PI regimens for 24 weeks. RESULTS: A high rate of virologic suppression was sustained with both regimens throughout the trial. At week 24, intent-to-treat:exposed (missing = failure) analyses showed no statistically significant differences in the percentage of patients with HIV-1 RNA <400 copies/mL (95% [QD] vs. 90% [BID]) or <50 copies/mL (82% [QD] vs. 81% [BID]) or in the median change from baseline in CD4 counts (+42 cells/mm(3) [QD] vs. +22 cells/mm(3) [BID]). Both regimens were well tolerated. No patient experienced virologic failure, clinical disease progression, or a drug-related serious adverse event during the trial. Self-reported medication adherence was high in both groups. CONCLUSION: Patients who experience virologic suppression with a regimen of lamivudine 150 mg BID in combination with stavudine/PI can maintain that suppression by continuing their regimen or switching to lamivudine 300 mg QD and continuing the other components. Adverse event profiles were comparable among treatment regimens, and no new safety concerns were raised.

Abacavir expanded access program for adult patients infected with human immunodeficiency virus type 1.

Expanded access programs (EAPs) provide medication to patients with life-threatening, treatment-refractory illnesses before regulatory approval and allow the acquisition of safety information. A 2-part, multisite EAP to evaluate abacavir, a carbocyclic nucleoside reverse-transcriptase inhibitor for use in combination antiretroviral therapy, was conducted. The EAP involved >13,000 adults infected with human immunodeficiency virus type 1 (HIV-1) who no longer responded to commercially available treatment regimens. Part A (open-label trials) examined the efficacy, safety, and tolerance of abacavir, and part B (provision of abacavir through expanded access) assessed only the occurrence of serious adverse events. By month 2 of abacavir-containing treatment, plasma HIV-1 RNA levels decreased by > or =0.5 log(10) in 31.4% of patients, and 5.6% of the patients had HIV-1 RNA levels decrease to <400 copies/mL. Drug-related serious adverse events were reported by 7.7% of patients, the most common of which were nausea, skin rash, diarrhea, malaise or fatigue, and fever. Approximately 4.6% of patients experienced a hypersensitivity reaction that was possibly drug related. Overall, the types and incidences of adverse events reported in the abacavir EAP were similar to those reported in phase 2 and 3 clinical trials evaluating abacavir.