Biomedical subjects

L Ruiz

Publications and source records attributed to L Ruiz.

At least 55 records · Page 3Linked to original sources

PubMed1999

Delta9-tetrahydrocannabinol induces apoptosis in human prostate PC-3 cells via a receptor-independent mechanism.

The effect of delta9-tetrahydrocannabinol (THC), the major psycho-active component of marijuana, in human prostate cancer cells PC-3 was investigated. THC caused apoptosis in a dose-dependent manner. Morphological and biochemical changes induced by THC in prostate PC-3 cells shared the characteristics of an apoptotic phenomenon. First, loss of plasma membrane asymmetry determined by fluorescent anexin V binding. Second, presence of apoptotic bodies and nuclear fragmentation observed by DNA staining with 4',6-diamino-2-phenylindole (DAPI). Third, presence of typical 'ladder-patterned' DNA fragmentation. Central cannabinoid receptor expression was observed in PC-3 cells by immunofluorescence studies. However, several results indicated that the apoptotic effect was cannabinoid receptor-independent, such as lack of an effect of the potent cannabinoid agonist WIN 55,212-2, inability of cannabinoid antagonist AM 251 to prevent cellular death caused by THC and absence of an effect of pertussis toxin pre-treatment.

Annexin A5↗

PubMed1999

Cerebrospinal fluid HIV-1 RNA levels in asymptomatic patients with early stage chronic HIV-1 infection: support for the hypothesis of local virus replication.

OBJECTIVE: To assess HIV-1 RNA levels in cerebrospinal fluid (CSF) and their potential correlation with plasma viral load and central nervous system (CNS) HIV-1 infection markers in stable asymptomatic patients with a CD4 T cell count >500x10(6) cells/l. PATIENTS AND METHODS: Consecutive patients screened for two trials were eligible for lumbar puncture assessment. At day 0, simultaneous samples of CSF and plasma were obtained and levels of total proteins, albumin, IgG, antibodies against HIV-1 p24 antigen, HIV-1 RNA (using the polymerase chain technique) and white cells were measured. RESULTS: The integrity of the blood-brain barrier was preserved (albumin index > or =7) in 59 out of 70 patients (84%). Intrathecal production of antibodies against HIV-1 p24 antigen was demonstrated in 55 out of 70 individuals (78%). Viral load in CSF was significantly lower than plasma values (3.13+/-0.95 versus 4.53+/-0.53, P = 0.0001). HIV-1 RNA was not detected in CSF in only three of the 70 patients (4%). Overall, there was a significant correlation between plasma and CSF HIV-1 RNA levels (r = 0.43, P = 0.0001); however, in 29 patients (41%) there were significant differences (>1.5 log10 copies/ml) between the viral loads in plasma and CSF. In the multivariate analysis, a high level of protein and white cells in CSF, but not the HIV-1 RNA plasma level, were factors independently associated with a higher level of HIV-1 RNA in CSF (P = 0.0001). CONCLUSIONS: HIV-1 RNA can be detected almost always in CSF of asymptomatic patients in early stages of HIV-1 infection including those with a preserved integrity of the blood-brain barrier. The important discrepancies between plasma and CSF viral load, and the independent association between CSF abnormalities and CSF viral load, support the hypothesis of local production of HIV-1.

Adult↗

PubMed1999

Quantification of integrated and total HIV-1 DNA after long-term highly active antiretroviral therapy in HIV-1-infected patients.

OBJECTIVE: To assess the impact of long-term virus suppression on the peripheral blood CD4 T cells integrated and total HIV-1 DNA loads in patients receiving highly active antiretroviral therapy (HAART). METHODS: A total of 10 HIV-1-infected patients receiving a triple combination therapy (two nucleoside analogues and one protease inhibitor) were longitudinally studied to compare integrated and total HIV-1 DNA loads. HIV-1 DNA quantification was performed using a quantitative nested polymerase chain reaction (PCR) on genomic peripheral blood mononuclear cell (PBMC) DNA obtained at baseline and at 48 weeks of HAART. RESULTS: All the study patients showed an early and sustained decrease in plasma HIV-1 RNA to below the limit of detection (200 copies/ml). Concordant with the plasma viral decline, a significant increase in the CD4 T cell count was observed (P = 0.007). A statistically significant fivefold decrease in total HIV-1 DNA was detected after 48 weeks of HAART (P = 0.005). However, no statistically significant change was noted after the therapy when the integrated HIV-1 DNA copy number was compared (P = 0.333). Taken together, these results suggest that in the patients analysed the integrated HIV-1 DNA does not decay rapidly after HAART. CONCLUSION: Within the study cohort the total amount of PBMC HIV-1 DNA decreased drastically after 48 weeks of HAART. Nevertheless, the integrated HIV-1 DNA did not significantly decay during this period. Although the data presented here are limited by the number of patients analysed, our findings suggest that 48 weeks of HAART does not significantly reduce the integrated HIV-1 proviral DNA load in the latently infected CD4 T cell reservoir.

Anti-HIV Agents↗

PubMed1999

Human immunodeficiency virus type 1 genetic evolution in patients with prolonged suppression of plasma viremia.

Treatment of human immunodeficiency virus type 1 (HIV-1)-infected patients with combination drug regimens results in a reduction of plasma viral load to levels below the limit of detection. To investigate the genomic fluctuations in HIV-1 populations from long-term responders to antiviral therapies we analyzed the viral sequence evolution of env and pol genes from sequential peripheral blood mononuclear cell (PBMC) DNA samples of three infected patients. Analyses of sequences covering the V3 and flanking env regions obtained from blood samples at the beginning of the therapy and at 14 or 24 months from baseline revealed that HIV-1 quasispecies continue to evolve in the three patients following combination antiretroviral therapy. Minor drug-resistant mutant subpopulations were also searched for and found in one patient. Interestingly, no minor resistant subpopulations were found in the other two patients despite the fact that they showed evidence of ongoing viral replication. Finally, the genetic analysis of the env gene shows a reduction in PBMC env viral population diversity after long-term response to the therapy in all the patients analyzed.

Anti-HIV Agents↗

PubMed1999

Chemokine and chemokine receptor expression after combined anti-HIV-1 interleukin-2 therapy.

OBJECTIVE: To evaluate changes in serum levels of chemokines, chemokine production, and chemokine receptor expression by peripheral blood mononuclear cells (PBMC), after treatment of HIV-1-infected individuals with interleukin (IL)-2. METHODS: We determined CC-chemokine levels by enzyme-linked immunosorbent assay and chemokine receptor expression using FACS analysis or reverse transcriptase polymerase chain reaction in samples from patients receiving highly active antiretroviral therapy (HAART) supplemented with low doses of recombinant IL-2. Results were compared with a control group of patients receiving HAART. RESULTS: Serum levels of RANTES, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta, and the production of these chemokines by unstimulated and stimulated PBMC, were not modified by IL-2 administration. In contrast, the IL-2-treated group showed increased expression of CXC-chemokine receptor (CXCR)-4 in the CD4 T-cell subset after 24 weeks of treatment, which was associated with increased mRNA levels. A lower increase was observed in CC-chemokine receptor (CCR)-5 expression by CD4 T cells. No modifications in the expression of these receptors were observed in monocytes and no general increases were observed in mRNA levels of chemokine receptors CCR-1, CCR-2b and CCR-3 in IL-2-treated patients. CONCLUSIONS: IL-2 at doses that significantly increase CD4 cell counts does not induce dramatic modifications in the chemokine/chemokine receptor system. Only expression of CXCR-4 appears to increase, due in part to lymphocyte activation. Therefore, the efficacy of IL-2 treatment in HIV-1 infection has to be evaluated by its ability to activate and induce faster regeneration of the immune system.

Anti-HIV Agents↗

PubMed1999

Protease inhibitor-containing regimens compared with nucleoside analogues alone in the suppression of persistent HIV-1 replication in lymphoid tissue.

OBJECTIVE: Lymphoid tissue provides a reservoir where HIV can persist. However, therapies incorporating a protease inhibitor can target this reservoir. This study was designed to investigate the relative long-term effects on lymph-node viral load and cellular architecture of regimens containing multiple nucleosides alone or in combination with protease inhibitors. METHODS: Axillary lymph-node biopsies from 12 patients with undetectable viraemia (viral load < 20 copies/ml: mean CD4 cells 525 x 10(6)/l) for a mean period of 25 months (range, 10-52 months) were investigated for the presence of HIV by in situ hybridization and coculture. Four patients were receiving multiple nucleoside analogues alone or in one case with a suboptimally dosed protease inhibitor (group I). Protease inhibitor was added to the regimen of seven patients at least 6 months prior to lymph-node biopsy (group II). Standard flow cytometry and virological data were obtained from peripheral blood every 3 months. RESULTS: By in situ hybridization, more productively infected CD4+ T cells were found in the lymph nodes of group I patients treated with nucleoside analogues alone. Very low numbers of productively infected lymph node cells were detected in the protease inhibitor-treated group II. No trapping of virions on the follicular dendritic cell (FDC) network was detectable in protease inhibitor-treated patients. In contrast, large deposits of FDC-bound virions were observed in three out of five patients from group I. Virus cultures from lymph node cells were positive in these three group I patients compared with only one out of seven patients from group II. Sequencing reverse transcriptase and protease genes from these isolates revealed typical mutations conferring resistance to the previously administered nucleoside analogue. A more preserved lymph node architecture and less signs of immunopathological change were also observed in protease inhibitor-treated patients. CONCLUSIONS: Undetectable plasma viraemia using the ultrasensitive PCR assay for prolonged periods of time does not always reflect complete HIV-1 suppression within the lymphoid compartment. Our results suggest that protease inhibitor-containing regimens target HIV reservoirs in lymphoid tissue more effectively and preserve or restore lymph node architecture.

Anti-HIV Agents↗

PubMed1999

Contraction of epithelial (MDCK) cells in response to low extracellular calcium is dependent on extracellular sodium.

Like other cells of epithelial origin, MDCK cells respond with a reversible structural transformation to a diminution in the concentration of extracellular Ca2+. Upon deprivation of Ca2+ in the medium the cells undergo an active contraction mediated by the actin-myosin cytoskeleton, in parallel to detachment of the intercellular contacts and appearance of free spaces in the epithelium or monolayer (Castillo et al., 1998). We now present results indicating that the decrease of external Ca2+ plays an indirect and non-specific role in activating contraction, probably by allowing an influx of Na+. The omission of external Ca2+ had no effect when it was replaced by Mg2+, Ba2+ or Hg2+, and the addition of any of these divalent cations induced relaxation of cells previously contracted by exposure to low Ca2+. A null or weak response was observed also when Ca2+ was lowered in a solution where Na+ was replaced by choline or in the presence of amiloride (30 microM), which reduces the permeability of the plasma membrane to Na+. Restitution of Na+ or removal of amiloride were followed by contraction in the same cultures. Li+ proved an able substitute of Na+ as requisite for cell contraction in response to Ca2+ depletion. Monensin (0.1 mM) -an ionophore selective for Na+- and to a lesser extent ouabain (0.1 mM) -an inhibitor of Na+ extrusion across the plasma membrane- , both stimulated contraction in the presence of the normal level of external Ca2+. Decreasing by half the normal concentration of external K+ facilitated cell contraction, but typical responses were observed when K+ was increased to 40 mM by partial substitution for Na+. These findings attest that cell contraction in response to low Ca2+ is likely due to an increase in the permeability of the plasma membrane to Na+, though not to membrane depolarization as such. Evidences from other motile systems suggest that Na+ influx might in turn cause an elevation of cytoplasmic Ca2+, which activates the actin-myosin cytoskeleton.

Amiloride↗

PubMed1999

Short-term risk for AIDS-indicator diseases predicted by plasma HIV-1 RNA and CD4+ lymphocytes.

The objective of this study was to assess the value of quantitative HIV-1 RNA as a predictor for the short-term risk of developing AIDS-defining events in comparison with CD4 cell counts. A total of 1,028 samples from 324 patients were analysed. Median initial CD4 cell counts and HIV-1 RNA were 249 x 10(6)/l (range 0-1400 x 10(6)/l) and 4.5 log copies/ml (range: 2.3-6.4 log copies/ml). CD4 cell counts and viral load (VL) values obtained the year before a single AIDS-indicator disease were selected to define the risk of developing that event. Cox regression models with CD4 cell counts and VL values treated as time-dependent covariates were performed to analyse the risk for developing certain events. Receiver operating characteristic (ROC) curves were used to compare CD4 cell counts and VL values as predictive markers for progression. During a median follow-up of 870 d (range 30-1381 d), 132 patients developed AIDS. Median log VL values during the year before the event were 3.6 for non-progressors and 5.2 for those who developed AIDS (p < 0.0001). Minimum log VL threshold values for developing diseases were 2.3 for tuberculosis, 3.8 for Candida esophagitis, 4.4 for wasting syndrome, 4.5 for CMV disease and 4.7 for PCP. VL values were not, however, a better predictive marker for developing specific events than were CD4 cell counts. Although we have identified VL thresholds for the risk of developing certain AIDS-indicator diseases, the indication for starting prophylactic regimens may still be based on CD4 cell counts.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Efficacy of low-dose subcutaneous interleukin-2 to treat advanced human immunodeficiency virus type 1 in persons with </=250/microL CD4 T cells and undetectable plasma virus load.

The immunologic efficacy of low-dose recombinant interleukin-2 (rIL-2) administered subcutaneously (sc) once a day in combination with highly active antiretroviral therapy (HAART) was assessed in a pilot study in patients with advanced human immunodeficiency virus (HIV) disease. Twenty-five persons with </=250 CD4 cells/microL and plasma HIV-1 RNA levels </=500 copies/mL for >24 weeks were randomly assigned to receive sc rIL-2 (3 x 10(6) IU once a day) with their previous antiretroviral regimen (n=13) or to continue with the same treatment (n=12). The level of CD4 T cells was significantly higher in the IL-2 group at week 24 (105+/-65/microL; P<.05) but not in the control group (30+/-78/microL). Memory T cells initially contributed to the CD4 T cell increase at week 4 (P<.05). Naive T cell increases (99+/-58/microL) in the IL-2 group became statistically significant at week 24 compared with the control group (28+/-27/microL; P<.05). Subcutaneous rIL-2 once a day in combination with HAART was well tolerated and improved immunologic surface markers in patients with advanced HIV infection.

Adult↗

PubMed1999

Phosphorylcholine-containing polyurethanes for the control of protein adsorption and cell attachment via photoimmobilized laminin oligopeptides.

In this study, we synthesized a biomaterial whose surface inhibits non-specific protein and cell attachment. The polymer was designed to mimic the external cell plasma membrane properties through the introduction of particular chemical constituents of the cell membrane: phospholipid polar headgroups. This was done by copolymerizing phosphorylcholine (PC) groups into a polyurethane polymer backbone (PCPUR). Peptides known to induce specific cell attachment were subsequently bound to the surface of this copolymer in a photoadressible manner to obtain surfaces that allowed the attachment of cells in a specific pattern. Two polymers with different phosphorylcholine concentrations were synthesized and their bulk and surface properties were characterized through differential scanning calorimetry, wettability measurements, angle-resolved X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Protein and lipid adsorption investigation using optical waveguide light mode spectroscopy showed that the irreversible adsorption of both proteins and lipids is drastically reduced as a result of simultaneous contributions of the PC groups, molecular mobility and strong hydrophilicity of the polymers. Consequently, this leads to a marked reduction in the cellular attachment response, which further decreases with increasing PC concentration. Finally, when the polymer surface was photo-derivatized, attachment of the neural NG108-15 cell line occurred only on the areas of the PCPUR where the laminin CDPGYIGSR peptide sequence was photoimmobilized. Cell attachment was nevertheless found to be non-specific with respect to the peptide sequence used and reasons for such results are therefore discussed.

Adsorption↗

PubMed1999

Development and application of a minimal-adenoviral vector system for gene therapy of hemophilia A.

To achieve efficient delivery and sustained expression of the human factor VIII cDNA in vivo, a minimal-adenoviral (mini-Ad) vector system was developed. The system is composed of a mini-Ad vector with essential cis-elements (less than 1 kb) of the viral genome, an E1-deleted ancillary Ad with packaging attenuation, and an E1-complementing production cell line. Based on this system, MiniAdFVIII was generated to deliver a 27 kb expression cassette consisting of a full-length human factor VIII cDNA flanked by human albumin promoter and genomic sequences. The MiniAdFVIII vector mediated expression of functional human factor VIII in HepG2 and 293 cells. A single-dose intravenous injection of 10(11) viral particles in hemophilic mice of MiniAdFVIII produced a sustained high-level expression of human factor VIII (at 100-800 ng/ml up to 369 days) which corrected the FVIII-deficient phenotype. Safety studies of MiniAdFVIII showed that there were no significant toxic effects in mice and dogs after single intravessel doses of up to 3 x 10(11) and 6 x 10(12) viral particles, respectively. Studies for developing the MiniAdFVIII vector with a site-specific integration mechanism and progress in the development of a human factor VIII-tolerized mouse model for pre-clinical studies of MiniAdFVIII are reported. Further pre-clinical studies and product development of MiniAdFVIII for clinical trials are also discussed.

Adenoviridae↗

PubMed1999

Presence of genotypic resistance in nucleoside analogue-treated HIV-1-infected patients with undetectable viral load.

Patients harbouring drug-resistance viruses usually suffer a rise in serum viraemia after a variable period of time. We have investigated the relationship between the appearance of resistant genotypes and the viral load of each patient after treatment. Our objective was to assess the association between human immunodeficiency virus (HIV) RNA plasma levels and the number of drug resistance-associated point mutations after treatment. A total of 150 patients from three reference centres in Spain (Madrid, Barcelona and Seville) from a previous study (Erase Study) were included. Patients had at that time undergone antiretroviral treatment with nucleoside analogues for at least 1 year (zidovudine/didanosine; zidovudine/zalcitabine; zidovudine/zalcitabine/lamivudine; zidovudine/didanosine/lamivudine). In this study, plasma viraemia in these patients was quantified and a line probe assay was used to determine the genotype of the virus. Viral load was significantly higher in patients harbouring virus with more than three mutations than in those individuals who harboured wild-type strains (P < 0.05). Surprisingly, when patients with viral load < 500 copies/ml (13/150) were analysed, only two carried wild-type strains, whereas three had virus with more than three point mutations. The viral load of six samples was assayed using an ultrasensitive test (detection limit < 20 copies/ml). Of the three samples where viral load was < 20 copies/ml, one patient harboured wild-type virus, whereas two carried mutant virus strains. These results suggest that even in patients with undetectable viral loads by conventional methods, viral replication may continue and mutations develop. Therefore, standard values of plasma viraemia for measuring the effectiveness of the treatment should be reconsidered when patients are on antiviral regimens of just two or three nucleoside analogues.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Efficiency of drug resistance genotypic tests in specimens with low HIV viral load.

The early recognition of resistance to antiretroviral agents could allow a rapid switch in therapy and therefore avoid the accumulation of mutations and reduce the risk of cross-resistance. However, the efficiency of genotypic tests in specimens with low viral load (VL) is severely compromised since human immunodeficiency virus (HIV) RNA in these samples often goes unrecognized. The frequency of results provided by a line probe assay (LiPA, Murex), a commercially available drug resistance test and a home-made point mutation assay (PMA) for recognizing the codon 151 multidrug-resistance mutation was examined in 664 plasma samples stratified with respect to VL values. Overall, 421 (63%) samples could be interpreted by both LiPA and PMA. The sensitivity decreased as plasma VL lowered: 89% for samples with VL > 10,000 HIV RNA copies/ml, 77% for those with VL between 500 and 10,000 HIV RNA copies/ml and 37% for specimens with VL < 500 HIV RNA copies/ml. A good agreement existed comparing the sensitivity of the home-made PMA and LiPA. Although the former tends to produce more results, the difference did not achieve statistical significance. Our results support that new, more sensitive, HIV RNA extraction methods need to be implemented for the rapid recognition of drug-resistant mutants in patients experiencing an early rebound in plasma viraemia.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Evolution of genotypic resistance to nucleoside analogues in patients receiving protease inhibitor-containing regimens.

The prevalence of genotypic resistance to nucleoside analogues (NA) was examined using a line probe assay (LiPA, Innogenetics, Spain) and a point mutation assay to test for codon 151 polymorphism in plasma from 34 individuals who had been exposed to NA for longer than 1 year. The testing was repeated in the same population after 6 months of being on a new potent protease inhibitor (PI)-containing antiretroviral combination. Only nine (47%) of the 19 patients initially carrying the codon 41 mutation restored zidovudine wild-type (WT) virus population. Similarly, eight (33%) out of 24 carrying the codon 215 mutation restored the wild-type variant. Two subjects carrying codon 74 didanosine mutation reverted to wild-type genotype, as well as two (18%) out of 11 harbouring the codon 184 lamivudine-resistant variant. To conclude, the extent to which drug recycling might be of benefit in subjects showing a restoration of genotypic sensitivity to former drugs needs to be explored.

Acquired Immunodeficiency Syndrome↗

PubMed1999

Benefit of switching from a protease inhibitor (PI) to nevirapine in PI-experienced patients suffering acquired HIV-related lipodystrophy syndrome (AHL): interim analysis at 3 months of follow-up.

This multicentre, randomized, open-label, prospective trial is evaluating the effects of switching treatment from a protease inhibitor (PI)-containing regimen to one containing the non-nucleoside reverse transcriptase (RT) inhibitor nevirapine in human immunodeficiency virus (HIV)-infected patients with durable viral suppression but suffering from lipodystrophy. Objectives of this ongoing study are to evaluate the effects of this switch on changes in body shape and metabolic abnormalities associated with acquired HIV-related lipodystrophy syndrome (AHL), as well as on maintenance of viral suppression and immunological and psychological effects. Preliminary data involving 57 patients with 3 months of follow-up show an initial improvement of AHL in two regions, the face and arms. There is also a tendency toward improved cholesterol and triglyceride levels and improved quality of life among patients receiving the nevirapine-containing regimen. Maintenance of viral suppression was equivalent in both treatment groups. Additional data with longer follow-up are needed to confirm these results.

Adult↗

PubMed1998

Multiple dideoxynucleoside analogue-resistant (MddNR) HIV-1 strains isolated from patients from different European countries.

OBJECTIVE: To study the prevalence of multiple dideoxynucleoside (ddN)-resistant (MddNR) HIV-1 in European patients under treatment with multiple ddN analogues, and to characterize MddNR strains genotypically and phenotypically. DESIGN AND METHODS: Blood samples from patients after > or = 6 months of treatment with multiple ddN were screened for the MddNR mutation Q151M. After confirmation of MddNR in 15 patients from five European countries, genotypic resistance was evaluated by DNA sequencing of the reverse transcriptase (RT) gene. Phenotypic resistance was measured by the recombinant virus assay. Results were compared with the clinical evolution of the patients. RESULTS: The prevalence of MddNR strains in European patients treated with multiple ddN analogues was 3.5%. Viruses typically contained amino acid substitutions V75F, F77L, F116Y and Q151M in the RT gene. A new mutation, S68G, was frequently associated with MddNR. Phenotypically, viruses displayed high-level resistance to zidovudine (ZDV), didanosine (ddl), zalcitabine (ddC), stavudine (d4T) and partial resistance to lamivudine (3TC) once multiple mutations were present. Under in-vivo treatment pressure, some MddNR strains additionally developed resistance to protease inhibitors or non-nucleoside RT inhibitors (NNRTI). Clinically, most patients had advanced HIV disease with low CD4 cell counts, high viral loads and a rapid progression, but two patients harbouring MddNR virus responded well to dual protease inhibitor associations. CONCLUSIONS: MddNR resistant HIV-1 can be found in European patients. MddNR is characterized by a specific set of drug resistance mutations, cross-resistance to most ddN analogues and a fast clinical progression. MddNR can be associated with protease inhibitor or NNRTI resistance.

Amino Acid Sequence↗

PubMed1998

Efficacy of adding indinavir to previous reverse transcriptase nucleoside analogues in relation to genotypic and phenotypic resistance development in advanced HIV-1-infected patients.

We assessed the efficacy of adding indinavir in patients with advanced HIV-1 infection, who were previously exposed to different reverse transcriptase (RT) nucleoside analogues. Twenty-five patients with an initial median CD4 cell count of 20 cells/mm3 (range, 0-80 cells/mm3) were treated with indinavir (800 mg three times per day) for 24 weeks. The median initial viral load was 5.4 log (range, 3.6-6.7 log). Of these patients, 56% (14 of 25) had an initial decrease in viral load of >1 log and sustained response of >0.5 log of HIV-1 RNA from baseline. Twelve of these 14 responder patients (85%) showed a sustained RNA response undetectable by NASBA assay, and no genotypic changes in protease were detected at week 24. In those with a temporary or absent response to indinavir, either resistant viruses or lack of compliance was observed. In compliant patients (15 of 16), relatively small increases in 50% inhibitory concentration (IC50) to indinavir and only two to three amino acid changes were sufficient to produce treatment failure. Phenotypic drug-resistant assays at 24 weeks revealed cross-resistance to ritonavir in all the patient isolates and to saquinavir in one third of the isolates. We observed an initial and persistent response to the addition of indinavir in patients with advanced disease and prolonged antiretroviral treatment. Therapy failure, as defined by increases in viral RNA, was associated with either lack of compliance or the development of low level indinavir-resistant virus. Clinical studies need to be designed to determine to what extent these viruses may respond to other protease inhibitors.

Anti-HIV Agents↗

PubMed1998

Predictive factors influencing peak viral load drop in response to nucleoside reverse transcriptase inhibitors in antiretroviral-naive HIV-1-infected patients.

Therapy with two nucleoside reverse transcriptase inhibitors (NRTI), the backbone of triple combinations, is still widely used in early stages of HIV-1 disease. However, factors influencing virologic response need to be further analyzed, to test the hypothesis that the reduction of plasma RNA viremia with NRTI may be greater in patients with higher baseline viral load (BVL) and to analyze the predictive factors of viral load drop below detection (200 HIV RNA copies/ml of plasma). Selected for the study were 169 HIV-1-infected antiretroviral therapy-naive patients with CD4+ T-lymphocyte counts ranging from 6 to 1040/microl coming from three randomized studies comparing the efficacy of monotherapy (zidovudine [ZDV], 250 mg every 12 hours; N=40) versus two-drug therapy consisting of ZDV (250 mg every 12 hours) with dideoxycytidine (ddC, 0.75 mg every 8 hours) or didanosine (ddI, 200 mg every 12 hours; N=129). Viral load was measured at 1, 3, and 6 months by polymerase chain reaction (PCR). A linear regression model was used to analyze the relation between BVL and the peak reduction of plasma RNA viremia. The variables included in a logistic regression model to determine the likelihood of VLs dropping below detection levels were age, gender, risk group for HIV-1 infection, baseline CD4+ lymphocyte count, BVL, clinical status (AIDS versus non-AIDS), HIV-1 phenotype (syncytium-inducing [SI] versus non-syncytium-inducing [NSI]) and type of treatment (monotherapy versus double therapy). The peak reduction of VL was related to baseline level following a linear model in both monotherapy and double-therapy regimens. In the subgroup of patients treated with two NRTIs, the regression line that fitted best with the data was log10 (peak reduction)=1.8-0.36 log10 (BVL) (F=23.5; p < .0001). This indicates that for every increase of 1 log10 of BVL, the peak reduction would be of 0.64 log10 greater. Forty-nine (29%) of the 169 patients dropped to <200 copies/ml. The likelihood of dropping below detection level was significantly greater in those receiving double therapy versus monotherapy (odds ratio [OR]=16.1; 95% confidence interval [CI], 2-128), in those with baseline CD4+ lymphocyte count >350/microl (OR=2.28; 95% CI, 1.1-4.9) and in those with BVL <10,000 HIV-1 RNA copies/ml (OR= 2.25; 95% CI, 1.1-6.1). None of the 13 patients with an SI phenotype at baseline dropped below detection levels. The reduction of VL in response to two NRTIs was greater in those patients with a higher level of BVL. In conclusion, peak reduction below detection in response to NRTI can be predicted and is associated with double therapy, with a baseline CD4+ cell count >350/microl and with a BVL <10,000 RNA copies/ml.

Adult↗