Polymorphisms of HIV-2 integrase and selection of resistance to raltegravir

<p>Abstract</p> <p>Background</p> <p>Human Immunodeficiency Virus type 2 is naturally resistant to some antiretroviral drugs, restricting therapeutic options for patients infected with HIV-2. Regimens including integrase inhibitors (INI) seem to be effective, but little data on HIV-2 integrase (IN) polymorphisms and resistance pathways are available.</p> <p>Materials and methods</p> <p>The <it>integrase </it>coding sequence from 45 HIV-2-infected, INI-naïve, patients was sequenced and aligned against the ROD (group A) or EHO (group B) reference strains and polymorphic or conserved positions were analyzed.</p> <p>To select for raltegravir (RAL)-resistant variants <it>in vitro</it>, the ROD strain was cultured under increasing sub-optimal RAL concentrations for successive rounds. The phenotype of the selected variants was assessed using an MTT assay.</p> <p>Results</p> <p>We describe <it>integrase </it>gene polymorphisms in HIV-2 clinical isolates from 45 patients. Sixty-seven percent of the integrase residues were conserved. The HHCC Zinc coordination motif, the catalytic triad DDE motif, and AA involved in IN-DNA binding and correct positioning were highly conserved and unchanged with respect to HIV-1 whereas the connecting residues of the N-terminal domain, the dimer interface and C-terminal LEDGF binding domain were highly conserved but differed from HIV-1. The N155 H INI resistance-associated mutation (RAM) was detected in the virus population from one ARV-treated, INI-naïve patient, and the 72I and 201I polymorphisms were detected in samples from 36 and 38 patients respectively. No other known INI RAM was detected.</p> <p>Under RAL selective pressure <it>in vitro</it>, a ROD variant carrying the Q91R+I175M mutations was selected. The Q91R and I175M mutations emerged simultaneously and conferred phenotypic resistance (13-fold increase in IC₅₀). The Q91R+I175M combination was absent from all clinical isolates. Three-dimensional modeling indicated that residue 91 lies on the enzyme surface, at the entry of a pocket containing the DDE catalytic triad and that adding a positive charge (Gln to Arg) might compromise IN-RAL affinity.</p> <p>Conclusions</p> <p>HIV-2 polymorphisms from 45 INI-naïve patients are described. Conserved regions as well as frequencies of HIV-2 IN polymorphisms were comparable to HIV-1. Two new mutations (Q91R and I175M) that conferred high resistance to RAL were selected <it>in vitro</it>, which might affect therapeutic outcome.</p

Whole-Body Magnetic Resonance Imaging in Rheumatic and Systemic Diseases: From Emerging to Validated Indications.

Whole-body magnetic resonance (MR) imaging techniques and protocols have been evolving continuously for the last 20 years, resulting in a powerful and mature tool for the detection, staging, and treatment monitoring of many oncologic and musculoskeletal disorders. The unique contrast resolution of MR imaging makes this imaging modality highly sensitive to pathologic alterations in bones, muscles, entheses, joints, and soft tissues, enabling this method to be expanded to the whole musculoskeletal system. Whole-body MR imaging is now used in numerous rheumatic, bone, and muscle disorders, and a full range of developing applications for this method have been emerging

Whole Body MRI: Non-oncological Musculoskeletal Applications

Purpose of the Review Whole-body MRI is an emerging imaging technique on continuous evolution, used in many oncologic indications and introduced more recently in rheumatologic and systemic disorders. In this article, we review the recent musculoskeletal applications of this technique outside the field of cancer. Recent Findings Whole-body MRI, with its high sensitivity to bone marrow and soft-tissue alterations, and ability of extensive body coverage, is progressively regarded as an effective and powerful imaging tool for the detection, staging, and monitoring under treatment of many rheumatic diseases and systemic pathologies affecting the musculoskeletal system. Disease specific imaging protocols have been designed. Summary Whole-body MRI is an appealing, non-irradiating tool emerging in musculoskeletal imaging. It is becoming the imaging of choice in several non-oncologic indications, and its application field is on continuous expansion

Whole-body MRI to assess bone involvement in prostate cancer and multiple myeloma: comparison of the diagnostic accuracies of the T1, short tau inversion recovery (STIR), and high b-values diffusion-weighted imaging (DWI) sequences.

PURPOSE: To compare the diagnostic accuracy of whole-body T1, short tau inversion recovery (STIR), high b-value diffusion-weighted imaging (DWI), and sequence combinations to detect bone involvement in prostate cancer (PCa) and multiple myeloma (MM) patients. MATERIALS AND METHODS: We included 50 consecutive patients with PCa at high risk for metastasis and 47 consecutive patients with a histologically confirmed diagnosis of MM who received whole-body MRI at two institutions from January to December 2015. Coronal T1, STIR, and reconstructed coronal high b-values DWI were obtained for all patients. Two musculoskeletal radiologists read individual sequences, pairs of sequences (T1-DWI, T1-STIR, and STIR-DWI), and all combined (T1-STIR-DWI) to detect bone involvement. Receiver operating characteristic curve analysis was used to assess diagnostic performance according to a "best valuable comparator" combining baseline and 6-month imaging and clinical and biological data. Interobserver agreement was calculated. RESULTS: Interobserver agreement for individual and combined MRI sequences was very good in the PCa group and ranged from good to very good in the MM group (0.76-1.00). In PCa patients, T1-DWI, T1-STIR, and T1-STIR-DWI showed the highest performance (sensitivity = 100% [95% CI = 90.5-100%], specificity = 100% [75.3-100%]). In MM patients, the highest performance was achieved by T1-STIR-DWI (sensitivity = 100% [88.4-100%], specificity = 94.1% [71.3-100%]). T1-STIR-DWI significantly outperformed all sequences (p < 0.05) except T1-DWI (p = 0.49). CONCLUSION: In PCa patients, a combination of either T1-DWI or T1-STIR sequences is not inferior to a combination of three sequences to detect bone metastases. In MM, T1-STIR-DWI and T1-DWI had the highest diagnostic performance for detecting bone involvement. KEY POINTS: • The sequences used in Whole Body MRI studies to detect bone involvement in prostate cancer and myeloma were evaluated. • In prostate cancer, any pairwise combinations of T1, STIR, and DWI have high diagnostic value. • In myeloma, the combinations T1-STIR-DWI or T1-DWI sequences should be used

Pattern of metastatic deposit in recurrent prostate cancer: a whole-body MRI-based assessment of lesion distribution and effect of primary treatment.

It is generally accepted that when metastases develop in a patient with biochemical recurrence of prostate cancer (PCa), they follow a centrifuge pattern of seeding from the pelvis and that most patients enter the disease as oligometastatic. In this study, we used whole-body magnetic resonance imaging (WB-MRI) to assess the anatomical distribution of oligo- and polymetastatic disease and the impact of the initial treatment on this distribution in patients. WB-MRI examinations of patients with a rising prostate-specific antigen (PSA) after radical treatment by surgery or/and radiotherapy were analyzed for disease recurrence. The patients were separated into three groups, based on the primary treatment: patients treated by radical prostatectomy without radiotherapy and with/without lymph node dissection (RP), patients treated only by radiotherapy or hormono-radiotherapy (RT) and patients treated with radical prostatectomy and adjuvant or salvage radiotherapy (RP + RT). Patients with ≤ 5 bone or/and node metastases were considered oligometastatic. Regional distributions of bone and lymph nodes metastases were reported using anatomical diagrams. Univariate and multivariable logistic regressions were performed to identify prognostic factors of relapse. The primary treatment (RP, RT, RP + RT), Gleason score, PSA at relapse, time between first diagnosis and recurrence did not influence the metastatic status (oligo vs. polymetastatic). Oligometastatic patients showed different distribution of bone metastases compared to the polymetastatic ones and the distribution of the oligometastatic disease was not influenced by the primary treatment. In this WB-MRI-based study, there was no evidence that the primary treatment influenced the metastatic status of the patient or the distribution of the oligometastatic disease

MRI versus F-FDG-PET/CT for detecting bone marrow involvement in multiple myeloma: diagnostic performance and clinical relevance.

PURPOSE: To compare the diagnostic performance of MRI and 18F-FDG-PET/CT in detecting bone marrow involvement (BMI) in patients with multiple myeloma (MM). MATERIALS AND METHODS: This retrospective study was approved by our Institutional Review Board. Two radiologists and two nuclear medicine specialists independently and blindly reviewed 84 pairs of MRI and PET/CT scans obtained in 73 MM patients. Readers assessed the presence and patterns of BMI. The best valuable comparator (BVC) for BMI was established by a panel review of all baseline and follow-up imaging, and biological and pathological information. Intra- and inter-reader agreement and correlation between MRI and PET/CT were assessed using the prevalence-adjusted bias-adjusted kappa (k) coefficient. Diagnostic performance of MRI and PET/CT in detecting BMI was evaluated from ROC characteristics. Association between imaging and biological, pathological, and clinical findings was assessed using Wilcoxon rank-sum and chi-square tests. RESULTS: Intra- and inter-reader agreement was very good for MRI (k = 0.90 [0.81; 1.00] and 0.88 [0.78; 0.98]). Intra- and inter-reader agreement was good for PET/CT (k = 0.80 [0.69; 0.91] and 0.71 [0.56; 0.86]). The sensitivity of MRI to detect BMI (97% [90%; 100%]) was significantly superior to that of PET/CT (76% [64%; 85%]) (p < 0.001). The specificity of MRI (86% [57%; 98%]) was lower than that of PET/CT (93% [66%; 100%]), without reaching statistical significance (p = 0.32). There was a strong correlation between decisions regarding patient management and PET/CT findings (p < 0.001). CONCLUSION: MRI is significantly more sensitive than PET/CT to detect BMI in MM. Patient management is more strongly correlated with PET/CT findings. KEY POINTS: • MRI and PET/CT have very close diagnostic value for the detection of bone marrow involvement in multiple myeloma. • MRI has a significantly higher sensitivity and better reproducibility. • PET/CT findings appear to have a higher impact on clinical decisions

Shortening the acquisition time of whole-body MRI: 3D T1 gradient echo Dixon vs fast spin echo for metastatic screening in prostate cancer.

To compare 3D T1-weighted fast spin echo (FSE) and 3D T1-weighted gradient echo (GE) mDixon as morphologic sequences to complement diffusion-weighted imaging (DWI) for the metastatic screening in prostate cancer (PCa) patients. Thirty PCa patients at high risk of metastases prospectively underwent both a 3D T1 FSE (14 min) and a rapid 3D T1 GE (1 min 20 s) sequences within a WB-MRI protocol. Two readers assessed the diagnostic performance of the FSE/Fat/in-phase (IP)/IP+Fat sequences in detecting bone and node metastases. The reference standard was established by a panel of four physicians on the basis of all baseline and follow-up imaging, biological and clinical information. The reproducibility of readings, predictive accuracy (Acc) from ROC curves analysis, and contrast-to-reference ratio (CRR) in lesions were assessed for each sequence. In bone and lymph nodes (per-region analysis), reproducibility was at least good for all sequences/readers, except for nodes in the common iliac/inguinal regions. In bone (per-organ analysis), Acc of FSE was superior to that of mDixon (difference + 4%, p < 0.0083). In nodes (per-organ analysis), Acc of Fat was superior to that of other sequences (difference + 4% to + 6% depending on reader, p < 0.0083). In the per-patient analysis, Acc of FSE was superior to that of mDixon (difference + 4% to + 6% depending on sequence, p < 0.0083). Fat images had higher CRR compared with FSE in the thoracic spine, the bony pelvis and lymph node metastases (p < 0.025). 3D T1 GE may replace 3D T1 FSE to complement DWI in WB-MRI for metastatic screening in PCa. It demonstrates an Acc ranging from + 4% to + 6% (nodes) to - 4% to - 6% (bone and patient staging) compared with FSE and considerably reduces the examination time, offering the perspective of acquiring WB-MRI examinations in less than 20 min. • The replacement of 3D T1 FSE by the 3D T1 GE mDixon as morphologic sequence to complement DWI drastically reduces the acquisition time of WB-MRI studies. • The 3D T1 GE mDixon sequence offers similar reproducibility of image readings compared with that of the 3D T1 FSE. • Differences in diagnostic accuracy are limited (+ 4%/+ 6% in favor of mDixon to detect node metastases; + 4%/+ 6% in favor of FSE to detect bone metastases/metastatic disease in a patient)

Magnetic resonance imaging (MRI) of the knee: Identification of difficult-to-diagnose meniscal lesions.

This article characterizes common meniscal pathologies, reviews magnetic resonance imaging (MRI) diagnostic criteria for meniscal tears, and identifies difficult-to-detect tears and fragments and the best MRI sequences and practices for recognizing these lesions. These difficult-to-diagnose meniscal lesions that radiologists should consider include tears, meniscocapsular separation lesions, and displaced meniscal fragments. Meniscus tears are either vertical, which are generally associated with traumatic injury, horizontal, which are associated with degenerative injury, or combinations of both. MRI has a high sensitivity for tears but not for fragments; MRI performance is also better for medial than lateral meniscal lesions. Fragment detection can be improved by recognizing signs secondary to migration, especially signs of epiphyseal irritation and mechanical impingement. Radial and peripheral tears, as well as those close to the posterior horn insertion, have been traditionally difficult to detect, but improvements in arthroscopic knowledge, identification of common lesion patterns, and selection of the proper MRI sequence and plane for each lesion type mean that, when properly used, MRI is an invaluable tool in detecting all types of meniscal tears