Determinants of blood telomere length in antiretroviral treatment-naïve HIV-positive participants enrolled in the NEAT 001/ANRS 143 clinical trial.

OBJECTIVES: Our aim was to investigate factors associated with baseline blood telomere length in participants enrolled in NEAT 001/ANRS 143, a randomized, open-label trial comparing ritonavir-boosted darunavir (DRV/r) plus raltegravir (RAL) with DRV/r plus tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) in antiretroviral therapy (ART)-naïve HIV-positive adults. METHODS: A cross-sectional study of 201 randomly selected participants who had stored samples available was carried out. We measured telomere length (i.e. the relative telomere length, calculated as the telomere to single copy gene ratio) at baseline with monochrome quantitative multiplex polymerase chain reaction (PCR). We used multivariable predictive linear regression to calculate mean differences and 95% confidence intervals (CIs) for the association between baseline telomere length and baseline characteristics. RESULTS: The baseline characteristics of the 201 participants did not differ from those of the 805 participants in the parent trial population: 89% were male, the mean age was 39 years, 83.6% were Caucasian, 93% acquired HIV infection via sexual transmission, the mean estimated time since HIV diagnosis was 2.1 years, the mean HIV-1 RNA load was 4.7 log10 HIV-1 RNA copies/mL, the mean nadir and baseline CD4 counts were 301 and 324 cells/µL, respectively, and the mean CD4:CD8 ratio was 0.4. In the univariate analysis, shorter telomere length was associated with older age (per 10 years) (P < 0.001), HIV-1 RNA ≥ 100 000 copies/mL (P = 0.001), CD4 count < 200 cells/µL (P = 0.037), lower CD4:CD8 ratio (P = 0.018), statin treatment (P = 0.004), and current alcohol consumption (P = 0.035). In the multivariable analysis, older age (P < 0.001) and HIV RNA ≥ 100 000 copies/mL (P = 0.054) were independently associated with shorter telomere length. CONCLUSIONS: Both age and HIV RNA viral load correlated with shorter blood telomere length in untreated persons living with HIV. These results suggest that HIV infection and age have synergistic and independent impacts upon immunosenescence.

Antiretroviral resistance at virological failure in the NEAT 001/ANRS 143 trial: raltegravir plus darunavir/ritonavir or tenofovir/emtricitabine plus darunavir/ritonavir as first-line ART.

OBJECTIVES: To describe the pattern of drug resistance at virological failure in the NEAT001/ANRS143 trial (first-line treatment with ritonavir-boosted darunavir plus either tenofovir/emtricitabine or raltegravir). METHODS: Genotypic testing was performed at baseline for reverse transcriptase (RT) and protease genes and for RT, protease and integrase (IN) genes for patients with a confirmed viral load (VL) >50 copies/mL or any single VL >500 copies/mL during or after week 32. RESULTS: A resistance test was obtained for 110/805 (13.7%) randomized participants qualifying for resistance analysis (61/401 of participants in the raltegravir arm and 49/404 of participants in the tenofovir/emtricitabine arm). No resistance-associated mutation (RAM) was observed in the tenofovir/emtricitabine plus darunavir/ritonavir arm, and all further analyses were limited to the raltegravir plus darunavir arm. In this group, 15/55 (27.3%) participants had viruses with IN RAMs (12 N155H alone, 1 N155H + Q148R, 1 F121Y and 1 Y143C), 2/53 (3.8%) with nucleotide analogue RT inhibitor RAMs (K65R, M41L) and 1/57 (1.8%) with primary protease RAM (L76V). The frequency of IN mutations at failure was significantly associated with baseline VL: 7.1% for a VL of <100,000 copies/mL, 25.0% for a VL of ≥100,000 copies/mL and <500,000 copies/mL and 53.8% for a VL of ≥500,000 copies/mL (PTREND = 0.007). Of note, 4/15 participants with IN RAM had a VL < 200 copies/mL at time of testing. CONCLUSIONS: In the NEAT001/ANRS143 trial, there was no RAM at virological failure in the standard tenofovir/emtricitabine plus darunavir/ritonavir regimen, contrasting with a rate of 29.5% (mostly IN mutations) in the raltegravir plus darunavir/ritonavir NRTI-sparing regimen. The cumulative risk of IN RAM after 96 weeks of follow-up in participants initiating ART with raltegravir plus darunavir/ritonavir was 3.9%.

Inactivation of Saccharomyces cerevisiae OGG1 DNA repair gene leads to an increased frequency of mitochondrial mutants.

The OGG1 gene encodes a highly conserved DNA glycosylase that repairs oxidized guanines in DNA. We have investigated the in vivo function of the Ogg1 protein in yeast mitochondria. We demonstrate that inactivation of ogg1 leads to at least a 2-fold increase in production of spontaneous mitochondrial mutants compared with wild-type. Using green fluorescent protein (GFP) we show that a GFP-Ogg1 fusion protein is transported to mitochondria. However, deletion of the first 11 amino acids from the N-terminus abolishes the transport of the GFP-Ogg1 fusion protein into the mitochondria. This analysis indicates that the N-terminus of Ogg1 contains the mitochondrial localization signal. We provide evidence that both yeast and human Ogg1 proteins protect the mitochondrial genome from spontaneous, as well as induced, oxidative damage. Genetic analyses revealed that the combined inactivation of OGG1 and OGG2 [encoding an isoform of the Ogg1 protein, also known as endonuclease three-like glycosylase I (Ntg1)] leads to suppression of spontaneously arising mutations in the mitochondrial genome when compared with the ogg1 single mutant or the wild-type. Together, these studies provide in vivo evidence for the repair of oxidative lesions in the mitochondrial genome by human and yeast Ogg1 proteins. Our study also identifies Ogg2 as a suppressor of oxidative mutagenesis in mitochondria.

Gastroesophageal reflux and obstructive sleep apnea.

OBJECTIVE: To determine the extent to which gastroesophageal reflux (GER)-initiated laryngeal chemoreflexes contribute to obstructive sleep apnea (OSA). METHODS: Prospective, nonrandomized clinical trial of an antireflux treatment protocol as a means of reducing the severity of OSA. Population consisted of 10 males aged 20 to 64 years with confirmed OSA (by overnight polysomnography) and GER (by ambulatory pH probe monitoring). Patients were treated with omeprazole and standard antireflux protocol for 30 days and pre- and posttreatment polysomnography variables were compared. RESULTS: Mean apnea index declined 31% (45-31, P = .04); mean respiratory disturbance index declined 25% (62-46, P = .06). Three patients (30%) are "treatment responders" as defined by traditional OSA treatment definitions. CONCLUSIONS: These results suggest a potential relationship between OSA and GER, the treatment of which may be an effective adjunctive in those with both disorders. Treatment of GER may significantly impact OSA in select individuals.

Purification of histidine-tagged mitochondrial ADP/ATP carrier: influence of the conformational states of the C-terminal region.

A functional recombinant mitochondrial ADP/ATP carrier from the yeast Saccharomyces cerevisiae that bears a six-histidine tag at the C-terminus, Anc2(His(6))p, has been engineered to allow its purification by immobilized metal-ion affinity chromatography (IMAC). The tagged carrier was expressed at a level similar to that of unmodified Anc2p as determined by immunodetection and titration of the specific atractyloside binding sites. Anc2(His(6))p, enriched by chromatography on hydroxyapatite of detergent extracts of mitochondria, was still contaminated by mitochondrial proteins and a large amount of ergosterol. It was highly purified after adsorption on Ni-NTA resin and elution by imidazole buffer, with a 90-95% overall yield. Anc2(His(6))p interacted differently with immobilized ions depending on whether it was unliganded or bound to carboxyatractyloside (CATR) or bongkrekic acid (BA), two specific inhibitors of the ADP/ATP transport, thus indicating that accessibility of the C-terminus is markedly influenced by the conformational state of the carrier. Fluorometric assays demonstrated that purified unliganded Anc2(His(6))p was in a functional state since it underwent CATR- and BA-sensitive and ADP (or ATP)-induced conformational changes. Large-scale purification of Anc2(His(6))p-CATR and Anc2(His(6))p-BA complexes by IMAC will be of major interest for structural analysis of the ADP/ATP carrier.

The mitochondrial ADP/ATP carrier: structural, physiological and pathological aspects.

Under the conditions of oxidative phosphorylation, the mitochondrial ADP/ATP carrier catalyses the one to one exchange of cytosolic ADP against matrix ATP across the inner mitochondrial membrane. The ADP/ATP transport system can be blocked very specifically by two families of inhibitors: atractyloside (ATR) and carboxyatractyloside (CATR) on one hand, and bongkrekic acid (BA) and isobongkrekic acid (isoBA) on the other hand. It is well established that these inhibitors recognise two different conformations of the carrier protein, the CATR- and BA-conformations, which exhibit different chemical, immunochemical and enzymatic reactivities. The reversible transition of the ADP/ATP carrier between the two conformations was studied by fluorometric techniques. This transconversion, which is only triggered by transportable nucleotides, is probably the same as that which occurs during the functioning of ADP/ATP transport system. The fluorometric approach, using the tryptophanyl residues of the yeast carrier as intrinsic fluorescence probes, was combined to a mutagenesis approach to elucidate the ADP/ATP transport mechanism at the molecular level. Finally, recent reports that myopathies might result from defect in ADP/ATP transport led us to develop a method to quantify the carrier protein in muscular biopsies.

Conformational changes of the yeast mitochondrial adenosine diphosphate/adenosine triphosphate carrier studied through its intrinsic fluorescence. 1. Tryptophanyl residues of the carrier can be mutated without impairing protein activity.

During the transport process the mitochondrial adenine nucleotide carrier (Ancp) undergoes conformational changes which result in modifications of the intrinsic fluorescence of the carrier. To further study these changes by a fluorometric approach, the three tryptophanyl residues (Trp87, Trp126, and Trp235) of the Saccharomyces cerevisiae Anc2p were individually mutated to their tyrosine counterparts. The resulting mutated genes (two-Trp, one-Trp or Trp-less variants) were integrated at the ANC2 locus. A prerequisite for such studies is that all the engineered carrier molecules are still able to catalyze ADP/ATP exchange. The cellular characteristics of the strains expressing the mutated Anc2p and the biochemical properties of the variant Anc2p in mitochondria were examined. Although Trp87 is absolutely conserved in all 30 available Ancp sequences, none of the tryptophanyl residues is essential to the carrier protein folding and the transport activity. The mutated and wild-type Anc2p were expressed to the same level, as evidenced by both ligand binding and immunochemical analyses. When isolated in the presence of detergent, all the variant Anc2p preparations contained ergosterol in similar amounts (9 mol/mol of 35 kDa Anc2p) but no specific interaction was revealed. Our results show that the tryptophanmutated Anc2p are suitable for fluorescence studies, which are reported in the accompanying paper by Roux et al. [(1996) Biochemistry 35, 16125-16131].

Conformational changes of the yeast mitochondrial adenosine diphosphate/adenosine triphosphate carrier studied through its intrinsic fluorescence. 2. Assignment of tryptophanyl residues of the carrier to the responses to specific ligands.

Tryptophanyl substitution of the Saccharomyces cerevisiae adenine nucleotide carrier (Anc2p isoform) was not deleterious for the transport activity or the folding of the carrier [preceding paper by Le Saux et al. (1996) Biochemistry 35, 16116-16124]. Conformational changes of the isolated wild-type and Trp-substituted Anc2p variants, induced upon binding of specific substrates [adenosine triphosphate (ATP) or diphosphate (ADP)] or inhibitors [carboxyatractyloside (CATR) or bongkrekic acid (BA)], were studied by measurement of intrinsic fluorescence. Titration of CATR and BA binding sites ended in the same number of sites, namely, 6-7 nmol/mg of wild-type and variant Anc2p. Isolated Anc2p in detergent presented similar emission spectra, suggesting that all tryptophanyl residues were in environments of similar hydrophobicity. Trp87 and Trp126 contributed largely and to a similar extent to the fluorescence enhancement observed in response to ATP binding, while Trp235 contributed negatively and to a small extent to the fluorescence change. Both Trp126 and Trp235, and to a lower extent Trp87, participate in the CATR-induced fluorescence decrease of Anc2p. Responses to BA binding were observed only in the presence of ATP; they consisted of a further fluorescence increase of the Anc2p.ATP complex, which was mainly due to Trp87 and Trp126, Trp235 being much less responsive. The different fluorescence responses of the three Trp residues of Anc2 variants to ATP, CATR, and BA are in agreement with distinct binding sites for these ligands and distinct conformations of the carrier protein recognizing specifically CATR or BA. A mechanistic model is proposed to interpret the transitions between the different conformational states of Anc2p.

Fluorometric titration of the mitochondrial ADP/ATP carrier protein in muscle homogenate with atractyloside derivatives.

We describe here the chemical synthesis of the novel methylanthraniloyl (Mant-) derivative of atractyloside (ATR), which is a specific inhibitor of the mitochondrial ADP/ATP carrier. The spectral properties of Mant-ATR and naphthoyl-ATR (N-ATR) are analyzed. Both derivatives bind to the membrane-bound ADP/ATP carrier at the same sites as ATR and carboxyatractyloside (CATR). When Mant-ATR and N-ATR are displaced by CATR, their fluorescence emissions are decreased and increased, respectively. These fluorescence changes allow the titration of the CATR binding sites and therefore the quantitation of the amount of ADP/ATP carrier protein in a biological preparation. The validity of the fluorometric titration was tested with beef heart mitochondria and confirmed by binding assays using radioactive ATR. The fluorometric method was applied to rabbit skeletal muscle homogenate and the results of titration were confirmed by binding assays of radioactive ATR. The reliability of the fluorometric method was assessed by comparing the amounts of CATR binding sites and the content of heme aa3 in muscle homogenates and in isolated mitochondria from the same homogenates. Because of its high sensitivity, the fluorometric titration of the ADP/ATP carrier requires small amounts of tissue. Mant-ATR and N-ATR can therefore be considered as convenient, reliable, and sensitive probes to quantify the amount of ADP/ATP carrier and detect a putative carrier protein deficiency in biopsy samples from human patients suffering from myopathies with no clear identified etiology.

Skull base tumor volume and surgical margins: a pilot study.

The relationship between preoperative assessment of tumor volume and oncologic adequacy of surgical margins was studied retrospectively. Our hypothesis was that the risk of inadequate, or positive, margins would rise with increasing tumor volume and that this would adversely affect survival. We anticipated that limitations of surgical approaches used until 1988 would be reflected in an increasing proportion of positive margins with increasing tumor volume. We conducted a pilot study of 25 patients with malignant tumors of the anterolateral cranial base operated on at the University of Pittsburgh Center for Cranial Base Surgery between 1987 and 1988. Preoperative computed tomography assessment of tumor volume was performed in all patients, and correlation between tumor volume, surgical margins, and survival was examined. Follow-up interval averaged 31.7 months. Twelve histologic tumor types were represented, with squamous cell carcinoma the most common (eight patients [32%]). Tumor volume ranged from 0.9 to 390 cc, with a median of 48 cc. Based on a median split of tumor volumes, patients were classified as high volume (more than 48 cc) or low volume (less than 48 cc). Of patients in the high volume group, 92% were found to have positive surgical margins, whereas only 50% of patients in the low volume group had positive margins. Analysis of the effect of tumor volume and surgical margins on survival was limited by sample size constraints, but both high-tumor volume and positive margins tended to reduce patient survival (0.07 < p 0.10).

Lipid peroxidation inhibitor attenuates noise-induced temporary threshold shifts.

The purpose of this study was to investigate the protective effects of U74389F (Upjohn Co. Kalamazoo, MI), a 21-aminosteroid/lipid peroxidation inhibitor, and a member of the lazaroid drug class, on temporary threshold shifts in animals exposed to prolonged noise stimulation. Animals treated with U74389F and exposed to noise showed attenuated cochlear action potential threshold (CAP) shifts and cochlear microphonic (CM) when compared to non-drug treated noise-exposed subjects. These data suggest that inhibition of FOR induced lipid peroxidation is an important mechanism in noise-induced asymptotic temporary threshold shifts.