Analysis of ART effects and drug resistance in adult HIV/AIDS patients in Meigu County, Liangshan Prefecture, China.

BACKGROUND OBJECTIVE: This study aimed to understand the basic situation of adults with human immunodeficiency virus (HIV) receiving antiretroviral therapy (ART) in Meigu County, Liangshan Yi Autonomous Prefecture. The information of patients who had been on ART for more than 6 months, the effect of ART, the possible reasons for ART failure, knowledge of drug resistance among patients with ART failure and the possible reasons for the emergence of drug resistance were analyzed. METHODS: A total of 2753 people living with HIV (PLWH) were collected for HIV-1 RNA virus nucleic acid testing. Plasma specimens with HIV-1 RNA ≥ 1000 copies/mL were sent to the laboratory for nucleic acid extraction, PCR, electrophoresis and sequencing, and the sequencing results were submitted to the HIV drug resistance database of Stanford University for subtyping to determine the drug resistance mutation sites and drug sensitivity levels. RESULTS: A total of 2753 patients were enrolled in this study. Antiviral therapy failed in 288 patients and was successfully amplified in 245, of which 111 had resistance genes. The resistance rate to failure of viral suppression was 45.3% (111/245). The highest rates of resistance to NNRTIs were found for efavirenz (EFV) and nevirapine (NVP) (42.9%), and the highest rates of resistance to NRTIs were found for 3TC and emtricitabine (FTC) (15.9%). The most common NNRTI resistance mutation site was K103N (20.8%), followed by V179D (9.4%) and V106M (7.8%); the most common NRTI resistance mutation site was M184V/I/MV (14.3%), followed by K65R (6.9%); three PI-associated resistance mutation sites were identified. The subtype of the resistant strain was CRF07-BC in almost all patients (98.9%). CONCLUSIONS: Compared with the previous low ART efficacy in the county, this study showed that the overall virological failure (VF) resistance rate in the county is still low, dominated by resistance to EFV, NVP, 3TC, FTC, and didanosine (DDI). Due to economic constraints, the core regimen is still 3TC + TDF, but before initiating ART, testing for HIV-1 subtypes and resistance should be conducted to avoid resistance that can lead to VF, especially for patients with high risk factors for resistance as shown by epidemiologic investigations.

PREVALENCE OF DIDANOSINE-RELATED RETINAL TOXICITY AT AN URBAN ACADEMIC CENTER AS DIAGNOSED WITH ULTRA-WIDEFIELD IMAGING.

PURPOSE: Antiretroviral therapy has revolutionized HIV treatment with didanosine (DDI) as a pioneering drug. However, DDI has been associated with retinal toxicity, characterized by peripheral chorioretinal degeneration with macular sparing. Despite its clinical recognition, the prevalence and risk factors for didanosine-induced retinopathy are not well described. METHODS: This retrospective case series analyzed 127 DDI-treated patients at Weill Cornell Medicine Department of Ophthalmology. Inclusion criteria included at least 6 months of DDI use and available ultra-widefield imaging. Patients were categorized as affected or unaffected based on retinal imaging assessed by two reviewers. The affected group was further divided into "probable" or "possible" retinopathy. Patient demographics, DDI usage characteristics, and imaging findings were analyzed with statistical comparisons drawn between affected and unaffected cohorts. RESULTS: Of the 127 patients, 9 (7%) showed signs of didanosine-induced retinal toxicity. On average, the affected group was older compared with the unaffected group (65.1 vs. 56.5 years, P = 0.025), with lower BMI (23.2 vs. 27.4, P = 0.04), and older at the start of the treatment (51.6 vs. 40.8 years, P = 0.026). Mild phenotypes with peripheral pigmentary changes were also identified using ultra-widefield imaging. CONCLUSION: This pioneering academic study highlighted a notable prevalence of DDI-induced retinal toxicity. Statistical analysis demonstrated age, BMI, and age at treatment initiation as potential risk factors. Ultra-widefield autofluorescence emerged as a valuable tool in detecting and delineating findings. Follow-up studies are needed to determine the necessity of regular screening for individuals on or with a history of didanosine use.

Synthesis, in silico and in vitro anti-cancer studies of phosphorylated derivatives of didanosine targeting MDA-MB-231 breast cancer cell lines.

A series of new phosphorylated derivatives of didanosine were designed, synthesized and evaluated their anticancer effects on human breast cancer cells. Their binding affinities were evaluated against aromatase enzyme and the molecular docking studies demonstrated that 9a, 9h and 9i exhibited high binding interactions than the parent molecule (ddI) and other derivatives; evaluated the aromatase enzyme inhibition. The cell viability, cell proliferation, lactate dehydrogenase showed potential anti-proliferative in dose dependent manner, these results were well correlated with hoesch stain and DNA fragmentation on MDA-MB-231 breast cancer cell lines. Cytotoxicity results disclosed that tryptophan amino acid ester substituted derivative 9i showed potential cell death against MDA-MB-231 cancer cell lines. Furthermore, compound 9i has great potential significance for further investigations (in vivo).

Insulin resistance in people living with HIV is associated with exposure to thymidine analogues and/or didanosine and prior immunodeficiency.

BACKGROUND: As people living with HIV (PLWH) are growing older, there is increased incidence of metabolic diseases, including type 2 diabetes mellitus, for which insulin resistance is a key determinant. In this study, we aimed to investigate risk factors associated with insulin resistance in PLWH. METHODS: We included well-treated PLWH without hepatitis co-infection, and with available fasting serum insulin and plasma glucose (n = 643) from the Copenhagen Comorbidity in HIV Infection Study. Insulin resistance was calculated using the homeostasis model assessment of insulin resistance (HOMA-IR). We investigated the association between risk factors and high HOMA-IR in a logistic regression model adjusted for age, sex, abdominal obesity, smoking status, and origin. When including use of thymidine analogues and/or didanosine in the model, we also adjusted for time with HIV. RESULTS: Median (IQR) age of PLWH was 52 years (46-61), and 87% (n = 557) were male. Median (IQR) HOMA-IR was 1.86 (1.23-3.14) mmol/L × mU/L. Risk factors significantly associated with high HOMA-IR included older age, BMI ≥ 25, abdominal obesity, waist circumference, use of thymidine analogues and/or didanosine, time with HIV, and CD4+ nadir < 200 cells/µL. CONCLUSIONS: Insulin resistance in PLWH is associated with both use of thymidine analogues and/or didanosine and prior immunodeficiency suggesting that increased attention on blood glucose in these patients could be beneficial.

Sustainable Protocol for the Synthesis of 2',3'-Dideoxynucleoside and 2',3'-Didehydro-2',3'-dideoxynucleoside Derivatives.

An improved protocol for the transformation of ribonucleosides into 2',3'-dideoxynucleoside and 2',3'-didehydro-2',3'-dideoxynucleoside derivatives, including the anti-HIV drugs stavudine (d4T), zalcitabine (ddC) and didanosine (ddI), was established. The process involves radical deoxygenation of xanthate using environmentally friendly and low-cost reagents. Bromoethane or 3-bromopropanenitrile was the alkylating agent of choice to prepare the ribonucleoside 2',3'-bisxanthates. In the subsequent radical deoxygenation reaction, tris(trimethylsilyl)silane and 1,1'-azobis(cyclohexanecarbonitrile) were used to replace hazardous Bu3SnH and AIBN, respectively. In addition, TBAF was substituted for camphorsulfonic acid in the deprotection step of the 5'-O-silyl ether group, and an enzyme (adenosine deaminase) was used to transform 2',3'-dideoxyadenosine into 2',3'-dideoxyinosine (ddI) in excellent yield.

A Rare Case of Didanosine-Induced Mid-Peripheral Chorioretinal Atrophy Identified Incidentally 11 Years after the Drug Cessation.

Objective: This article aims to describe a unique case of didanosine-induced retinal degeneration that was discovered 11 years after the drug withdrawal. Case report: The patient is a 42-year-old woman with a medical history of HIV and hepatitis C virus since 2004. She has been prescribed antiretroviral therapy since then. For the first seven years (2004-2011), the patient was prescribed a combination therapy consisting of didanosine, efavirenz, and lamivudine. The protocol was changed to atripla (efavirenz, emtricitabine, and tenofovir) from 2011 to 2021. Recently (October 2021-January 2021), the patient was prescribed eviplera (rilpivirin, emtricitabine, and tenofovir). In addition, her past medical history revealed Gougerot-Sjogren syndrome and rheumatoid arthritis. She was prescribed hydroxychloroquine (HCQ) (2009-2021) at a dose of 400 mg daily. She had no vision complaint. Results: During her routine HCQ screening at the eye clinic, University Hospital Bretonneau, Tours, France, the widefield colour fundus photograph showed well-defined symmetric mid-peripheral areas of chorioretinal atrophy sparing the posterior pole of both eyes. Furthermore, the widefield fundus autofluorescence illustrated mid-peripheral round well-demarcation hypoautofluorescent areas of chorioretinal atrophy of both eyes. Conversely, the macular optical coherence tomography (OCT) was normal. Many of her drugs are known to be associated with retinopathy such as HCQ, tenofovir, efavirenz, and didanosine. Because our data corroborate peripheral retinal damage rather than posterior pole damage, this case report is compatible with didanosine-induced retinopathy rather than HCQ, efavirenz, or tenofovir retinal toxicity. Conclusions: All HIV patients who are presently or were previously on didanosine therapy should have their fundus examined utilising widefield fundus autofluorescence and photography.

Increased Prevalence of Liver Fibrosis in People Living With Human Immunodeficiency Virus Without Viral Hepatitis Compared to Population Controls.

BACKGROUND: Liver fibrosis is associated with poor liver-related outcomes and mortality. People with human immunodeficiency virus (PWH) may be at increased risk. We aimed to estimate the prevalence and factors associated with liver fibrosis in PWH compared to population controls. METHODS: This was a cross-sectional cohort study comparing 342 PWH with 2190 population controls aged 50-70 years.Transient elastography was performed and elevated liver stiffness measurement (LSM) defined as 7.6 kPa as a proxy for significant liver fibrosis. Adjusted odds ratios (aORs) and 95% confidence intervals (95% CIs) were computed by logistic regression. RESULTS: The prevalence of elevated LSM was higher in PWH than in uninfected controls (12% vs 7%; P < .01). Human immunodeficiency virus (HIV) infection was independently associated with elevated LSM. In multivariate analysis, elevated LSM was associated with HIV (aOR, 1.84 [95% CI, 1.17-2.88]; P < .01); higher age (per decade: aOR, 3.34 [95% CI, 1.81-6.18]; P < .01); alanine aminotransferase (ALT) (per 10 IU/L: aOR, 1.25 [95% CI, 1.05-1.49]; P < .01); body mass index (BMI) (per 1 kg/m2: aOR, 1.17 [95% CI, 1.05-1.29]; P < .01), and previous exposure to didanosine (per year: aOR, 2.26 [95% CI, 1.01-5.06]; P = .04). CONCLUSIONS: The prevalence of elevated LSM was higher in PWH compared to population controls. Higher age, BMI, ALT, previous exposure to didanosine, and positive HIV status were independently associated with higher odds of elevated LSM.

Pericardial Adipose Tissue Volume Is Independently Associated With Human Immunodeficiency Virus Status and Prior Use of Stavudine, Didanosine, or Indinavir.

BACKGROUND: Increased pericardial adipose tissue is associated with higher risk of cardiovascular disease. We aimed to determine whether human immunodeficiency virus (HIV) status was independently associated with larger pericardial adipose tissue volume and to explore possible HIV-specific risk factors. METHODS: Persons with HIV (PWH) were recruited from the Copenhagen Comorbidity in HIV Infection (COCOMO) Study and matched 1:1 on age and sex to uninfected controls. Pericardial adipose tissue volume was measured using cardiac computed tomography. RESULTS: A total of 587 PWH and 587 controls were included. Median age was 52 years, and 88% were male. Human immunodeficiency virus status was independently associated with 17 mL (95% confidence interval [CI], 10-23; P < .001) larger pericardial adipose tissue volume. Larger pericardial adipose tissue volume was associated with low CD4+ nadir and prior use of stavudine, didanosine, and indinavir. Among PWH without thymidine analogue or didanosine exposure, time since initiating combination antiretroviral treatment (per 5-year use) was associated with l6 mL (95% CI, -6 to -25; P = .002) lower pericardial adipose tissue volume. CONCLUSIONS: Human immunodeficiency virus status was independently associated with larger pericardial adipose tissue volume. Severe immunodeficiency, stavudine, didanosine, and indinavir were associated with larger pericardial adipose tissue volume. Persons with HIV with prior exposure to these drugs may constitute a distinct cardiovascular risk population.

Mass spectrometric investigations into the brain delivery of abacavir, stavudine and didanosine in a rodent model.

HIV replication in the brain is unopposed due to reduced antiretroviral drug penetration into the central nervous system (CNS). Prevalence of HIV-associated neurocognitive disorder (HAND) has increased severely in patients living with HIV despite current treatments. The aims of this study were to evaluate the brain bio-distribution of alternative nucleoside reverse transcriptase inhibitors, abacavir, stavudine and didanosine in the CNS and to determine their localization patterns in the brain.Sprague-Dawley rats received 50 mg kg-1 single i.p dose of each drug. Mass spectrometric techniques were then used to investigate the pharmacokinetics and localization patterns of these drugs in the brain using LC-MS/MS and mass spectrometric imaging (MSI), respectively.Abacavir, stavudine and didanosine reached the Brain Cmax with concentration of 831.2, 1300 and 43.37 ngmL-1, respectively. Based on MSI analysis Abacavir and Stavudine were located in brain regions that are strongly implicated in the progression of HAND.Abacavir and Stavudine penetrated into CNS, reaching a Cmax that was above the IC50 for HIV (457.6 and 112.0 ngmL-1, respectively), however, it was noted ddI showed poor entry within the brain, therefore, it is recommended that this drug cannot be considered for treating CNS-HIV.

Evaluation of a Library of FDA-Approved Drugs for Their Ability To Potentiate Antibiotics against Multidrug-Resistant Gram-Negative Pathogens.

The Prestwick library was screened for antibacterial activity or "antibiotic resistance breaker" (ARB) potential against four species of Gram-negative pathogens. Discounting known antibacterials, the screen identified very few ARB hits, which were strain/drug specific. These ARB hits included antimetabolites (zidovudine, floxuridine, didanosine, and gemcitabine), anthracyclines (daunorubicin, mitoxantrone, and epirubicin), and psychoactive drugs (gabapentin, fluspirilene, and oxethazaine). These findings suggest that there are few approved drugs that could be directly repositioned as adjunct antibacterials, and these will need robust testing to validate efficacy.

Metabolic events in HIV-infected patients using abacavir are associated with erythrocyte inosine triphosphatase activity.

Objectives: Abacavir use has been associated with an increased risk of cardiovascular disease (CVD) and metabolic events in HIV-infected patients, although this finding was not consistently found. It is unclear whether abacavir only increases this risk in subpopulations of HIV-infected patients. It may be hypothesized that inosine 5'-triphosphate pyrophosphohydrolase (ITPase), an enzyme involved in the metabolism of purine analogues used in HIV treatment, plays a role in the risk of CVD and metabolic events in HIV-infected patients. Methods: ITPase activity and ITPA genotype were determined in 393 HIV-infected patients. ITPase activity <4 mmol IMP/mmol Hb/h was considered decreased. ITPA polymorphisms tested were: c.94C>A (rs1127354) and c.124 + 21A>C (rs7270101). ORs were determined using generalized estimating equation models for developing CVD in patients who had ever been exposed to abacavir, tenofovir or didanosine and for developing metabolic events in patients currently using these drugs. Results: In patients using abacavir, metabolic events were associated with ITPase activity. No association was demonstrated for tenofovir or didanosine. The OR for metabolic events was 3.11 in patients using abacavir with normal ITPase activity (95% CI 1.34-7.21; P = 0.008) compared with patients with decreased ITPase activity [adjusted for age, BMI, cumulative duration of combination ART (cART) use and the use of PI and NNRTI]. CVD was not associated with ITPase activity or ITPA genotype. Conclusions: This study shows, for the first time, that ITPase activity is associated with the occurrence of metabolic events in patients using abacavir. Further studies are needed to confirm this association and to elucidate the possible mechanism.

Long-lasting alterations in adipose tissue density and adiponectin production in people living with HIV after thymidine analogues exposure.

BACKGROUND: Thymidine analogues (TA) and didanosine (ddI) are associated with long-lasting adipose tissue redistribution. Adiponectin is a widely used marker of adipocyte activity, and adipose tissue density assessed by CT-scan is associated with adipocyte size and function. We hypothesized that prior exposure to TA and ddI was associated with long-lasting adipose tissue dysfunction in people living with HIV (PLWH). Thus, we tested possible associations between markers of adipose tissue dysfunction (adipose tissue density and adiponectin) and prior exposure to TA and/or ddI, years after treatment discontinuation. METHODS: Eight hundred forty-eight PLWH from the COCOMO study were included and stratified according to prior exposure to TA and/or ddI (with, n = 451; without n = 397). Visceral (VAT) and subcutaneous (SAT) adipose tissue area and density were determined by single slice abdominal CT-scan at lumbar 4th level. Venous blood was collected and analyzed for adiponectin. Multivariable linear and logistic regression analyses were used to test our hypotheses. Multivariable models were adjusted for age, sex, smoking, origin, physical activity, BMI, and adipose tissue area (VAT or SAT area, accordingly to the outcome). RESULTS: prior exposure to TA and/or ddI was associated with excess risk of low VAT (adjusted OR (aOR) 1.74 [1.14; 2.67]) and SAT density (aOR 1.74 [1.18; 2.58]), for a given VAT and SAT area, respectively. No association between VAT and SAT density with time since TA and/or ddI discontinuation was found. 10 HU increase in VAT density was associated with higher adiponectin plasma level and this association was not modified by prior exposure to TA and/or ddI. Prior exposure to TA and/or ddI was associated with 9% lower [- 17;-2] plasma adiponectin levels and with excess risk of low adiponectin (aOR 1.74 [1.10; 2.76]). CONCLUSIONS: We described low adipose tissue density and impaired adiponectin production to be associated with prior exposure to TA and/or ddI even years after treatment discontinuation and independently of adipose tissue area. These findings suggest that prior TA and ddI exposure may have long-lasting detrimental effects on adipose tissue function and, consequently, on cardiometabolic health in PLWH.

Chronic kidney disease and HIV in the era of antiretroviral treatment: findings from a 10-year cohort study in a west African setting.

BACKGROUND: It has been reported that people living with HIV in West Africa exhibited the highest risks for chronic kidney disease (CKD) in the world. Here, we aimed at determining the CKD frequency and changes in kidney function during antiretroviral treatment (ART) in a large cohort of HIV-patients followed in Burkina Faso. METHODS: We included ART-naive adults who initiated ART at the Day Care Unit of the Souro Sanou University Hospital between 01/01/2007 and 12/31/2016. We assessed the estimated glomerular filtration rate (eGFR) by serum creatinine using the Modification of Diet in Renal Disease (MDRD) equation. Following the K/DOQI recommendations, CKD was defined as eGFR < 60 ml/min/1.73m2 at two consecutive measurements at least 3 months apart. The factors associated with eGFR decline or CKD were identified by mixed linear regression and Cox regression, respectively. RESULTS: Three thousand, one hundred and thirty-eight patients (72% women) were followed for a median (IQR) of 4.5(2.2-6.9) years. At baseline, median eGFR (IQR) was 110.7(94.4-128.4) ml/min/1.73m2 and 93 (3%) patients exhibited eGFR < 60 ml/min/1.73m2. The lowest-performing progressions of eGFR during the first year of ART were observed in patients with 40-49 yr. age range (- 8.3[- 11.7;-5.0] ml/min/1.73m2, p < 0.001), age ≥ 50 yr. (- 6.2[- 10.7;-1.8] ml/min/1.73m2, p = 0.006) and high blood pressure (HBP) (- 28.4[- 46.9;-9.9] ml/min/1.73m2, p = 0.003) at ART initiation. Regarding the ART exposure in patients with normal baseline eGFR, zidovudine (AZT) with protease inhibitor (PI) (- 4.7[- 7.7;-1.6] ml/min/1.73m2, p = 0.002), tenofovir (TDF) + PI (- 13.1[- 17.4;-8.7] ml/min/1.73m2, p < 0.001), TDF without PI (- 3.2[- 5.0;-1.4] ml/min/1.73m2, p < 0.001), stavudine (d4T) + PI (- 8.5[- 14.6-2.4] ml/min/1.73m2, p = 0.006) and d4T without PI (- 5.0[- 7.6-2.4] ml/min/1.73m2, p < 0.001) were associated with poorer eGFR progression. The prevalence of CKD was 0.5% and the incidence was 1.9 [1.3; 2.7] cases/1000 person-years. The risk of CKD was higher in patients with HBP (4.3[1.8;9.9], p = 0.001), 40-49 yr. patients (4.2[1.6;11.2], p = 0.004), ≥50 yr. patients (4.5[1.5;14.1], p = 0.009) and patients exposed to abacavir (ABC) or didanosine (ddI) based ART (13.1[4.0;42.9], p < 0.001). CONCLUSIONS: Our findings do not confirm the high risk of CKD reported in previous studies of West Africans with HIV, but support the recommendations for early initiation of ART and close kidney function monitoring in patients with HBP or aged ≥40 yr.

A Lower Baseline CD4/CD8 T-Cell Ratio Is Independently Associated with Immunodiscordant Response to Antiretroviral Therapy in HIV-Infected Subjects.

We explored if baseline CD4/CD8 T-cell ratio is associated with immunodiscordant response to antiretroviral therapy in HIV-infected subjects. Comparing immunodiscordant and immunoconcordant subjects matched by pretreatment CD4 counts, we observed a lower pretreatment CD4/CD8 T-cell ratio in immunodiscordant subjects. Furthermore, pretreatment CD4/CD8 T-cell ratio, but not CD4 counts, correlated with the main immunological alterations observed in immunodiscordants, including increased regulatory T-cell (Treg) frequency and T-cell turnover-related markers. Then, in a larger cohort, only baseline CD4/CD8 T-cell ratio was independently associated with immunodiscordance, after adjusting by the viral CXCR4-tropic HIV variants. Our results suggest that the CD4/CD8 T-cell ratio could be an accurate biomarker of the subjacent immunological damage triggering immunodiscordance.

Structural Insights into HIV Reverse Transcriptase Mutations Q151M and Q151M Complex That Confer Multinucleoside Drug Resistance.

HIV-1 reverse transcriptase (RT) is targeted by multiple drugs. RT mutations that confer resistance to nucleoside RT inhibitors (NRTIs) emerge during clinical use. Q151M and four associated mutations, A62V, V75I, F77L, and F116Y, were detected in patients failing therapies with dideoxynucleosides (didanosine [ddI], zalcitabine [ddC]) and/or zidovudine (AZT). The cluster of the five mutations is referred to as the Q151M complex (Q151Mc), and an RT or virus containing Q151Mc exhibits resistance to multiple NRTIs. To understand the structural basis for Q151M and Q151Mc resistance, we systematically determined the crystal structures of the wild-type RT/double-stranded DNA (dsDNA)/dATP (complex I), wild-type RT/dsDNA/ddATP (complex II), Q151M RT/dsDNA/dATP (complex III), Q151Mc RT/dsDNA/dATP (complex IV), and Q151Mc RT/dsDNA/ddATP (complex V) ternary complexes. The structures revealed that the deoxyribose rings of dATP and ddATP have 3'-endo and 3'-exo conformations, respectively. The single mutation Q151M introduces conformational perturbation at the deoxynucleoside triphosphate (dNTP)-binding pocket, and the mutated pocket may exist in multiple conformations. The compensatory set of mutations in Q151Mc, particularly F116Y, restricts the side chain flexibility of M151 and helps restore the DNA polymerization efficiency of the enzyme. The altered dNTP-binding pocket in Q151Mc RT has the Q151-R72 hydrogen bond removed and has a switched conformation for the key conserved residue R72 compared to that in wild-type RT. On the basis of a modeled structure of hepatitis B virus (HBV) polymerase, the residues R72, Y116, M151, and M184 in Q151Mc HIV-1 RT are conserved in wild-type HBV polymerase as residues R41, Y89, M171, and M204, respectively; functionally, both Q151Mc HIV-1 and wild-type HBV are resistant to dideoxynucleoside analogs.

An association between K65R and HIV-1 subtype C viruses in patients treated with multiple NRTIs.

Objectives: HIV-1 subtype C might have a greater propensity to develop K65R mutations in patients with virological failure compared with other subtypes. However, the strong association between viral subtype and confounding factors such as exposure groups and ethnicity affects the calculation of this propensity. We exploited the diversity of viral subtypes within the UK to undertake a direct comparative analysis. Patients and methods: We analysed only sequences with major IAS-defined mutations from patients with virological failure. Prevalence of K65R was related to subtype and exposure to the NRTIs that primarily select for this mutation (tenofovir, abacavir, didanosine and stavudine). A multivariate logistic regression model quantified the effect of subtype on the prevalence of K65R, adjusting for previous and current exposure to all four specified drugs. Results: Subtype B patients ( n = 3410) were mostly MSM (78%) and those with subtype C ( n = 810) were mostly heterosexual (82%). K65R was detected in 7.8% of subtype B patients compared with 14.2% of subtype C patients. The subtype difference in K65R prevalence was observed irrespective of NRTI exposure and K65R was frequently selected by abacavir, didanosine and stavudine in patients with no previous exposure to tenofovir. Multivariate logistic regression confirmed that K65R was significantly more common in subtype C viruses (adjusted OR = 2.02, 95% CI = 1.55-2.62, P < 0.001). Conclusions: Patients with subtype C HIV-1 have approximately double the frequency of K65R in our database compared with other subtypes. The exact clinical implications of this finding need to be further elucidated.

[Non-cirrhotic portal hypertension due to didanosina. A rare case]. / Hipertensión portal no cirrótica por didanosina. Un caso infrecuente.

Liver involvement is usually seen in patients infected with the human immunodeficiency virus (HIV), especially in patients coinfected with hepatitis B or C, in alcohol abuse, etc. However, there is a group of patients who develop liver involvement and portal hypertension of unspecified cause. Non-cirrhotic portal hypertension (NCPH) is a liver disorder recently described, but potentially serious. It has been reported in HIV-infected patients with highly active antiretroviral therapy (HAART), specifically didanosine (DDI). The pathophysiology involves the infectious agent (HIV) and its treatment (HAART), since both generate a pre-hepatic portal venulopathy. Similarly, HIV infection produces a prothrombotic state by protein S deficiency leading to the obliteration of small hepatic venules. It has been postulated that DDI as a cofactor in the pathogenesis of NCPH. All this leads that many of the liver biopsies show nodular regenerative hyperplasia. We present the case of a HIV-infected patient who was treated with a longstanding DDI. She developed upper gastrointestinal bleeding (UGB) and ascites due to NCPH, whose diagnosis was confirmed by biopsy. However, there is no similar study in our country.

The purine analogues abacavir and didanosine increase acetaminophen-induced hepatotoxicity by enhancing mitochondrial dysfunction.

BACKGROUND: NRTIs are essential components of HIV therapy with well-documented, long-term mitochondrial toxicity in hepatic cells, but whose acute effects on mitochondria are unclear. As acetaminophen-induced hepatotoxicity also involves mitochondrial interference, we hypothesized that it would be exacerbated in the context of ART. METHODS: We evaluated the acute effects of clinically relevant concentrations of the most widely used NRTIs, alone or combined with acetaminophen, on mitochondrial function and cellular viability. RESULTS: The purine analogues abacavir and didanosine produced an immediate and concentration-dependent inhibition of oxygen consumption and complex I and III activity. This inhibition was accompanied by an undermining of mitochondrial function, with increased production of reactive oxygen species and reduction of mitochondrial membrane potential and intracellular ATP levels. However, this interference did not compromise cell survival. Co-administration with concentrations of acetaminophen below those considered hepatotoxic exacerbated the deleterious effects of both compounds on mitochondrial function and compromised cellular viability, showing a clear correlation with diminished glutathione levels. CONCLUSIONS: The simultaneous presence of purine analogues and low concentrations of acetaminophen significantly potentiates mitochondrial dysfunction, increasing the risk of liver injury. This new mechanism is relevant given the liver's susceptibility to mitochondrial dysfunction-related toxicity and the tendency of the HIV infection to increase oxidative stress.

Prevalence of drug resistance mutations in HAART patients infected with HIV-1 CRF06_cpx in Estonia.

HIV-1 drug resistance mutations (DRMs) and substitutions were assessed after the failure of the first line non-nucleoside reverse transcriptase inhibitors (NNRTIs) + 2 nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) treatment regimens (efavirenz [EFV] + lamivudine[3TC] + zidovudine [ZDV] vs. EFV + 3TC + ddI) among the HIV-1 CRF06_cpx infected subjects in Estonia. HIV-1 genomic RNA was sequenced; DRMs and amino acid substitutions were compared in 44 treatment naïve and 45 first-line NNRTI + 2 NRTI treatment failed patients consisting of EFV + 3TC + ZDV (n = 17) and EFV + 3TC + didanosine[ddI] (n = 21) therapy failed sub-populations. At least one DRM was found in 78% of treatment experienced patients. The most common NRTI mutations were M184V (80%), L74V (31%), L74I (17%), K219E (9%), and M184I (9%), NNRTI mutations were K103N (83%), P225H (14%), L100I (11%), and Y188L (11%), reflecting generally the similar pattern of DRMs to that seen in treatment failed subtype B viruses. Sub-population analysis revealed that EFV + 3TC + ddI failed patients had more DRMs compared to EFV + 3TC + ZDV failed patients, especially the ddI DRM L74IV and several additional NNRTI DRMs. Additionally, CRF06_cpx specific mutation E179V and substitutions R32K, K122E, and V200AE were also detected in treatment experienced population. After the failure of the first-line EFV + 3TC + ddI therapy HIV-1 CRF06_cpx viruses develop additional NRTI and NNRTI mutations compared to EFV + 3TC + ZDV regimen. Therefore the usage of EFV + 3TC + ddI in this subtype decreases the options for next regimens containing abacavir, and NNRTI class agents.

Bioretrosynthetic construction of a didanosine biosynthetic pathway.

Concatenation of engineered biocatalysts into multistep pathways markedly increases their utility, but the development of generalizable assembly methods remains a major challenge. Herein we evaluate 'bioretrosynthesis', which is an application of the retrograde evolution hypothesis, for biosynthetic pathway construction. To test bioretrosynthesis, we engineered a pathway for synthesis of the antiretroviral nucleoside analog didanosine (2',3'-dideoxyinosine). Applying both directed evolution- and structure-based approaches, we began pathway construction with a retro-extension from an engineered purine nucleoside phosphorylase and evolved 1,5-phosphopentomutase to accept the substrate 2,3-dideoxyribose 5-phosphate with a 700-fold change in substrate selectivity and threefold increased turnover in cell lysate. A subsequent retrograde pathway extension, via ribokinase engineering, resulted in a didanosine pathway with a 9,500-fold change in nucleoside production selectivity and 50-fold increase in didanosine production. Unexpectedly, the result of this bioretrosynthetic step was not a retro-extension from phosphopentomutase but rather the discovery of a fortuitous pathway-shortening bypass via the engineered ribokinase.