975 resultados para Posttranslational Modifications
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Search of new activity substances starting from chemotherapeutic agents, continously appears in international literature. Perhaps this search has been done more frequently in the field of anti-tumor chemotherapy on account of the unsuccess in saving advanced stage patients. The new point in this matter during the last decade was computer aid in planning more rational drugs. In near future "the accessibility of supercomputers and emergence of computer net systems, willopen new avenues to rational drug design" (Portoghese, P. S. J. Med. Chem. 1989, 32, 1). Unknown pharmacological active compounds synthetized by plants can be found even without this eletronic devices, as tradicional medicine has pointed out in many contries, and give rise to a new drug. These compounds used as found in nature or after chemical modifications have produced successful experimental medicaments as FAA, "flavone acetic acid" with good results as inibitors of slow growing animal tumors currently in preclinical evaluation for human treatment. In this lecture some international contributions in the field of chemical modified compounds as antineoplasic drugs will be examined, particularly those done by Brazilian researches.
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Le don de sang représente un acte solidaire. Il est le plus souvent bénévole et, selon les pays et les circonstances, non rémunéré. Les éléments de la réflexion éthique sont, entre autres, l'augmentation des besoins, les critères d'exclusion de plus en plus nombreux, l'exigence sécuritaire et les modifications des structures de nos sociétés. Compte tenu de cela, les acteurs de la chaîne transfusionnelle doivent s'interroger sur certains paramètres : la valeur du don, le sens du bénévolat, l'opportunité de rémunérer l'acte de livrer une partie de soi, non plus comme un don et comme une expression d'altruisme et de solidarité, mais comme une prestation commerciale définie par des règles économiques. Blood donation is an act of solidarity. Most often, this act is done on a volunteer basis and, depending on countries and circumstances, is not remunerated. The increase in need, the always-greater number of deferral criteria, the safety issues and the changes in the structures of our societies are among the many subjects for ethical debates. Taking these into account, the actors of the transfusion must analyze certain parameters: the value of a donation, the meaning of volunteering, the appropriateness of remunerating the act of giving a part of one's self, no longer as a donation or an expression of altruism and solidarity, but as a commercial act regimented by economic laws.
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Le retard de croissance intra-utérin (RCIU) est défini par une taille et un poids inférieurs au P10 pour l'âge gestationnel. Il est caractérisé, entre autre par une altération de la croissance foetale aboutissant à une résistance à l'hormone de croissance (HC). Bien que la majorité des sujets présente un certain rattrapage en taille, certains développent un retard de croissance ultérieur permanent. L'idée est donc née de traiter ces sujets par haute dose d'HC biosynthétique. La question des risques d'un tel traitement s'est posée en raison de l'effet diabétogène de l'HC et des modifications qu'elle peut induire sur la masse maigre, la masse grasse et la densité osseuse. Le but de l'étude a été d'évaluer l'impact sur la croissance et sur le volet métabolique. Dix enfants prépubères ayant présenté un RCIU sans croissance de rattrapage spontanée ont été traités par HC recombinante à des doses supra physiologiques (53-67 g/kg/jour). La taille, le poids, la taille assise ont été mesurés et des dosages d'IGF1, IGFBP3, glycémie et insuline ont été faits sur une base semestrielle alors qu'une densitométrie osseuse a été faite annuellement sur une période de 3 ans. Le gain en taille a été spectaculaire (+ 1.78 DS), correspondant à plus de 10 cm (p < 0.001). Sous traitement, l'insulinémie et le HOMA ont augmenté sans que ces augmentations soient significatives. La tolérance glucidique est restée dans la norme au prix d'une augmentation de la sécrétion d'insuline. La masse grasse a diminué alors que la masse maigre et la densité osseuse ont augmenté de façon significative. Ces résultats correspondent aux travaux d'autres groupes. Il reste à démontrer que l'hyperinsulinisme transitoire induit par l'HC n'ait pas d'effet néfaste à long terme et en particulier sur le risque de développer ou aggraver un syndrome métabolique à l'âge adulte.
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Coiled bodies (CBs) are structural constituents observed in nuclei of most eukaryotic cells. They usually occur in the nucleoplasm as well as in contact with the nucleolar surface. In this work we studied the hepatocyte nuclei of hibernating dormice in order to investigate possible modifications of CBs along the seasonal cycle. CBs were abundant during hibernation and rapidly disappeared upon arousal from hibernation. Moreover, CBs were frequently found to be integrated into the nucleolar body. Immunocytochemical analyses showed that CBs contain nucleoplasmic as well as nucleolar RNA-processing factors, suggesting an "ambiguous" role for this organelle in the nuclear functions.
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Issue addressed: Cutaneous melanoma is a significant health problem in New Zealand. Excessive sun exposure in early life increases subsequent risk. This study investigated parental opinions, understanding and practices concerning the sun protection of young children. The study aimed to identify areas where improvements in sun protection may be most needed. Methods: Parents were recruited through licensed childcare centres and kindergartens in Dunedin to take part in semi-structured focus groups. Feedback was obtained from participants in response to summary reports based on audiotapes. Results: Parents noted increased social acceptability of sun protective behaviours and child sunburn was now unacceptable. Past media campaigns were well recalled. The 'time to burn' used in media weather reports was easier to understand than the Ultra Violet Index (UVI), about which more information was wanted. Protective messages were expected to be straightforward, consistent and readily and regularly available. Local radio may provide the most timely, relevant information. There was a perceived lack of authoritative information about sunscreens and sunglasses and a shortage of acceptable protective clothing. Fuller information on sunscreen containers and greater use of UV Protection Factor (UPF) ratings for clothing and Eye Protection Factor (EPF) for sunglasses would assist. The use of shade and rescheduling of activities were scarcely mentioned. Conclusions: Parents were aware of the need for child sun protection but lacked confidence about how best to achieve this. Future health promotion programs should emphasise how optimal protection can be achieved more than why sun protection is needed. Programs should include a repertoire of strategies targeted towards individuals through the education of children and caregivers. They should also aim at achieving modifications in physical and social environments, including appropriate product design and promotion. So what?: The development of a balanced, comprehensive program with environmental components that reinforce protective behaviours has the potential to sustain sun protection among the largest number of children in the longer term.
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BACKGROUND: The Nuclear Factor I (NFI) family of DNA binding proteins (also called CCAAT box transcription factors or CTF) is involved in both DNA replication and gene expression regulation. Using chromatin immuno-precipitation and high throughput sequencing (ChIP-Seq), we performed a genome-wide mapping of NFI DNA binding sites in primary mouse embryonic fibroblasts. RESULTS: We found that in vivo and in vitro NFI DNA binding specificities are indistinguishable, as in vivo ChIP-Seq NFI binding sites matched predictions based on previously established position weight matrix models of its in vitro binding specificity. Combining ChIP-Seq with mRNA profiling data, we found that NFI preferentially associates with highly expressed genes that it up-regulates, while binding sites were under-represented at expressed but unregulated genes. Genomic binding also correlated with markers of transcribed genes such as histone modifications H3K4me3 and H3K36me3, even outside of annotated transcribed loci, implying NFI in the control of the deposition of these modifications. Positional correlation between + and - strand ChIP-Seq tags revealed that, in contrast to other transcription factors, NFI associates with a nucleosomal length of cleavage-resistant DNA, suggesting an interaction with positioned nucleosomes. In addition, NFI binding prominently occurred at boundaries displaying discontinuities in histone modifications specific of expressed and silent chromatin, such as loci submitted to parental allele-specific imprinted expression. CONCLUSIONS: Our data thus suggest that NFI nucleosomal interaction may contribute to the partitioning of distinct chromatin domains and to epigenetic gene expression regulation.NFI ChIP-Seq and input control DNA data were deposited at Gene Expression Omnibus (GEO) repository under accession number GSE15844. Gene expression microarray data for mouse embryonic fibroblasts are on GEO accession number GSE15871.
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Pond-breeding amphibians are affected by site-specific factors and regional and landscape-scale patterns of land use. Recent anthropogenic landscape modifications (drainage, agriculture intensification, larger road networks, and increased traffic) affect species by reducing the suitable habitat area and fragmenting remaining populations. Using a robust concentric approach based on permutation tests, we evaluated the impact of recent landscape changes on the presence of the endangered European tree frog (Hyla arborea.) in wetlands. We analyzed the frequency of 1 traffic and 14 land-use indices at 20 circular ranges (from 100-m up to 2-km radii) around 76 ponds identified in western Switzerland. Urban areas and road surfaces had a strong adverse effect on tree frog presence even at relatively great distances (from 100 m up to 1 km). When traffic measurements were considered instead of road surfaces, the effect increased, suggesting a negative impact due to a vehicle-induced effect. Altogether, our results indicate that urbanization and traffic must be taken into account when pond creation is an option in conservation management plans, as is the case for the European tree frog in western Switzerland. We conclude that our easy-to-use and robust concentric method of analysis can successfully assist managers in identifying potential sites for pond creation, where probability of the presence of tree frogs is maximized.
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Biological invasions and land-use changes are two major causes of the global modifications of biodiversity. Habitat suitability models are the tools of choice to predict potential distributions of invasive species. Although land-use is a key driver of alien species invasions, it is often assumed that land-use is constant in time. Here we combine historical and present day information, to evaluate whether land-use changes could explain the dynamic of invasion of the American bullfrog Rana catesbeiana (=Lithobathes catesbeianus) in Northern Italy, from the 1950s to present-day. We used maxent to build habitat suitability models, on the basis of past (1960s, 1980s) and present-day data on land-uses and species distribution. For example, we used models built using the 1960s data to predict distribution in the 1980s, and so on. Furthermore, we used land-use scenarios to project suitability in the future. Habitat suitability models predicted well the spread of bullfrogs in the subsequent temporal step. Models considering land-use changes predicted invasion dynamics better than models assuming constant land-use over the last 50 years. Scenarios of future land-use suggest that suitability will remain similar in the next years. Habitat suitability models can help to understand and predict the dynamics of invasions; however, land-use is not constant in time: land-use modifications can strongly affect invasions; furthermore, both land management and the suitability of a given land-use class may vary in time. An integration of land-use changes in studies of biological invasions can help to improve management strategies.
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This observational study analyzed imatinib pharmacokinetics and response in 2478 chronic myeloid leukemia (CML) patients. Data were obtained through centralized therapeutic drug monitoring (TDM) at median treatment duration of ≥2 years. First, individual initial trough concentrations under 400mg/day imatinib starting dose were estimated. Second, their correlation (C^min(400mg)) with reported treatment response was verified. Low imatinib levels were predicted in young male patients and those receiving P-gp/CYP3A4 inducers. These patients had also lower response rates (7% lower 18-months MMR in male, 17% lower 1-year CCyR in young patients, Kaplan-Meier estimates). Time-point independent multivariate regression confirmed a correlation of individual C^min(400mg) with response and adverse events. Possibly due to confounding factors (e.g. dose modifications, patient selection bias), the relationship seemed however flatter than previously reported from prospective controlled studies. Nonetheless, these observational results strongly suggest that a subgroup of patients could benefit from early dosage optimization assisted by TDM, because of lower imatinib concentrations and lower response rates.
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BACKGROUND/AIMS: Ligand activation of the mineralocorticoid receptor (MR) induces several post-translational modifications (PTMs). Among the different PTMs, MR is known to be dynamically ubiquitylated with impact on its stability and transcriptional activity. Previously, we have shown that MR is monoubiquitylated at the basal state and that aldosterone stimulation induces monoubiquitylation removal prompting polyubiquitin-dependent destabilization of the receptor and proteasomal degradation. This study investigated the role of the aldosterone induced ubiquitin-specific protease USP2-45 on the ubiquitylation state of MR. METHODS: Renal epithelial cells M1 were co-transfected with MR with or without wild-type or inactive USP2-45. The association of MR with USP2-45 or TSG101 as well as MR ubiquitylation state were determined by immunoprecipitation and immunoblotting. MR transcriptional activity was assessed via a luciferase reporter gene. RESULTS: We show that USP2-45 is able to bind MR and, similarly to aldosterone, induce MR monoubiquitylation removal, disruption of MR/TSG101 association and destabilization of MR at protein level. CONCLUSION: This study provides a novel role for USP2-45 by playing a pivotal role in the regulation of the ubiquitylation state of MR and reveals the existence of a negative feedback loop for limiting the aldosterone induced response.
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Résumé Streptococcus gordonii est une bactérie colonisatrice naturelle de la cavité buccale de l'homme. Bien que normalement commensale, elle peut causer des infections graves, telles que des bactériémies ou des endocardites infectieuses. La pénicilline étant un des traitements privilégiés dans de tels cas, l'augmentation rapide et globale des résistances à cet antibiotique devient inquiétante. L'étude de la physiologie et des bases génétiques de ces résistances chez S. gordonii s'avère donc importante. Les cibles moléculaires privilégiées de la pénicilline G et des β-lactames sont les penicilllin-binding proteins (PBPs). Ces enzymes associées à la membrane ont pour rôle de catalyser les réactions de transpeptidation et de transglycosylation, qui constituent les dernières étapes de la biosynthèse du peptidoglycan (PG). Elles sont définies comme classe A ou B selon leur capacité d'assurer soit les deux réactions, soit uniquement la transpeptidation. Les β-lactames inhibent le domaine transpeptidase de toutes les PBPs, entraînant l'inhibition de la synthèse du PG, l'inhibition de la croissance, et finalement la mort cellulaire. Chez les streptocoques, les PBPs sont aussi les premiers déterminants de la résistance à la pénicilline. De plus, elles sont impliquées dans la morphologie bactérienne, en raison de leur rôle crucial dans la formation du PG. Le but de ce travail était de caractériser les PBPs de S. gordonii et d'étudier leurs fonctions dans la vie végétative de la bactérie ainsi que durant le développement de la résistance à la pénicilline. Premièrement, des mutants auxquels il manque une ou deux PBP(s) ont été construits. Leur étude - au niveau physiologique, biochimique et morphologique - a montré le caractère essentiel ou dispensable de chaque protéine, ainsi que certaines de leurs fonctions potentielles. Deuxièmement, des mutants résistants à la pénicilline ont été générés. Leur caractérisation a montré l'importance des mutations dans les PBPs ainsi que dans d'autres gènes encore inconnus, de même que le rôle crucial des PBPs de classe A dans le développement de la résistance à la pénicilline. Des expériences supplémentaires sur des isolats résistants ont aussi prouvé que la résistance a un coût en terme de fitness, coût que S. gordonii parvient à compenser par des mécanismes d'adaptation. Finalement, les promoteurs des gènes des PBPs ont été déterminés et leur expression a été étudiée grâce au gène de luciférase. Il a ainsi été montré que la résistance à la pénicilline entraîne non seulement des altérations au niveau des protéines, mais aussi au niveau de la régulation des gènes. De plus, la pénicilline génère directement des modifications dans l'expression de PBPs spécifiques. Summary Streptococcus gordonii is a normal inhabitant of the human oral cavity and a pioneer colonizer of teeth. Although usually considered as a commensal, this organism can cause life-threatening infections such as bacteraemia or endocarditis. Since penicillin is one of the preferential treatments for such pathologies, the rapid and general increase of antibiotic resistance in the overall population becomes an issue. Thus, studying the physiologic and genetic bases of such a resistance in S. gordonii is of interest. The primary molecular targets of penicillin G and other β-lactams are the so called penicillin-binding proteins (PBPs). These are membrane-associated proteins that catalyze the last steps in peptidoglycan (PG) biosynthesis, namely transpeptidation and transglycosylation. Depending on their capacity to catalyze either reactions or only transpeptidation, they are considered as class A or class B PBPs, respectively. β-lactam antibiotics inhibit the transpeptidase domain of both of these classes of enzymes, resulting in inhibition of PG assembly, inhibition of bacterial growth, and ultimately leading to cell death. In streptococci, PBPs are also the primary determinants of penicillin-resistance. Moreover, because of their crucial role in PG formation, they are implicated in fundamental aspects of cell morphology. The goal of this work was thus to characterize S. gordonii PBPs and to explore their functions in terms of vegetative life and penicillin-resistance development. First, single and double PBP-inactivated mutants were generated and their effect on the bacterial physiology, cell wall biochemistry and ultrastructural morphology was assessed. This demonstrated the essentiality or dispensability of each protein for bacterial life. Second, penicillin-resistant mutants were generated by cyclic exposure to increasing concentrations of the drug. Characterization of these mutants pointed out the importance of both PBP and non-PBP mutations, as well as the crucial role of the class A PBPs in the development of penicillin-resistance. Further experiments on resistant isolates demonstrated the fitness cost of this resistance, but also the capacity of S. gordonii to adapt and regain the fitness of the wild-type. Finally, the promoters of PBP genes were determined and their expression was monitored using luciferase fusions. This showed that penicillin-resistance, in addition to modifications at the level of the protein, also triggered genetic alterations. Moreover, penicillin itself generated modifications in the expression of specific PBPs.
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SUMMARY : Eukaryotic DNA interacts with the nuclear proteins using non-covalent ionic interactions. Proteins can recognize specific nucleotide sequences based on the sterical interactions with the DNA and these specific protein-DNA interactions are the basis for many nuclear processes, e.g. gene transcription, chromosomal replication, and recombination. New technology termed ChIP-Seq has been recently developed for the analysis of protein-DNA interactions on a whole genome scale and it is based on immunoprecipitation of chromatin and high-throughput DNA sequencing procedure. ChIP-Seq is a novel technique with a great potential to replace older techniques for mapping of protein-DNA interactions. In this thesis, we bring some new insights into the ChIP-Seq data analysis. First, we point out to some common and so far unknown artifacts of the method. Sequence tag distribution in the genome does not follow uniform distribution and we have found extreme hot-spots of tag accumulation over specific loci in the human and mouse genomes. These artifactual sequence tags accumulations will create false peaks in every ChIP-Seq dataset and we propose different filtering methods to reduce the number of false positives. Next, we propose random sampling as a powerful analytical tool in the ChIP-Seq data analysis that could be used to infer biological knowledge from the massive ChIP-Seq datasets. We created unbiased random sampling algorithm and we used this methodology to reveal some of the important biological properties of Nuclear Factor I DNA binding proteins. Finally, by analyzing the ChIP-Seq data in detail, we revealed that Nuclear Factor I transcription factors mainly act as activators of transcription, and that they are associated with specific chromatin modifications that are markers of open chromatin. We speculate that NFI factors only interact with the DNA wrapped around the nucleosome. We also found multiple loci that indicate possible chromatin barrier activity of NFI proteins, which could suggest the use of NFI binding sequences as chromatin insulators in biotechnology applications. RESUME : L'ADN des eucaryotes interagit avec les protéines nucléaires par des interactions noncovalentes ioniques. Les protéines peuvent reconnaître les séquences nucléotidiques spécifiques basées sur l'interaction stérique avec l'ADN, et des interactions spécifiques contrôlent de nombreux processus nucléaire, p.ex. transcription du gène, la réplication chromosomique, et la recombinaison. Une nouvelle technologie appelée ChIP-Seq a été récemment développée pour l'analyse des interactions protéine-ADN à l'échelle du génome entier et cette approche est basée sur l'immuno-précipitation de la chromatine et sur la procédure de séquençage de l'ADN à haut débit. La nouvelle approche ChIP-Seq a donc un fort potentiel pour remplacer les anciennes techniques de cartographie des interactions protéine-ADN. Dans cette thèse, nous apportons de nouvelles perspectives dans l'analyse des données ChIP-Seq. Tout d'abord, nous avons identifié des artefacts très communs associés à cette méthode qui étaient jusqu'à présent insoupçonnés. La distribution des séquences dans le génome ne suit pas une distribution uniforme et nous avons constaté des positions extrêmes d'accumulation de séquence à des régions spécifiques, des génomes humains et de la souris. Ces accumulations des séquences artéfactuelles créera de faux pics dans toutes les données ChIP-Seq, et nous proposons différentes méthodes de filtrage pour réduire le nombre de faux positifs. Ensuite, nous proposons un nouvel échantillonnage aléatoire comme un outil puissant d'analyse des données ChIP-Seq, ce qui pourraient augmenter l'acquisition de connaissances biologiques à partir des données ChIP-Seq. Nous avons créé un algorithme d'échantillonnage aléatoire et nous avons utilisé cette méthode pour révéler certaines des propriétés biologiques importantes de protéines liant à l'ADN nommés Facteur Nucléaire I (NFI). Enfin, en analysant en détail les données de ChIP-Seq pour la famille de facteurs de transcription nommés Facteur Nucléaire I, nous avons révélé que ces protéines agissent principalement comme des activateurs de transcription, et qu'elles sont associées à des modifications de la chromatine spécifiques qui sont des marqueurs de la chromatine ouverte. Nous pensons que lés facteurs NFI interagir uniquement avec l'ADN enroulé autour du nucléosome. Nous avons également constaté plusieurs régions génomiques qui indiquent une éventuelle activité de barrière chromatinienne des protéines NFI, ce qui pourrait suggérer l'utilisation de séquences de liaison NFI comme séquences isolatrices dans des applications de la biotechnologie.
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Techniques for cerebral hemispherectomy have progressively evolved towards more disconnection and less excision over the last 50 years. Peri-insular hemispherotomy (PIH), as described by the senior author, has the maximal ratio of disconnection to excision among all procedures for hemispheric epilepsy. In this study, we focus on surgical complications and intraoperative anatomical observations during PIH over the last 10 years. Based on this experience, the procedure has undergone some modifications, which we detail herein.
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In this work we have studied the modifications in the biological properties of Trypanosoma cruzi when the parasite is maintained for a long time in axenic culture. The studies were done with a clone from an avirulent strain (Dm30L) and a non-cloned virulent strain (EP) of T. cruzi. Both parasiteswere maintained, for at least three years, by successive triatomine/mouse alternate passage (control condition), or by serial passage in axenic medium (culture condition), or only in the mouse (mouse condition). The comparison between parasites of culture and control condition showed that metacyclogenesis capacity was reduced in the former and that the resulting metacyclics displayed an attenuatedvirulence. In order to compare the virulence of metacyclics from the urine of the insect vector, Rhodnius prolixus were infected by artificial feeding with parasites of the control or culture condition. After three triatomine/triatomine passages, there was observed an almost identical biological behavior for these parasites, hence indicating that the maintenance of T. cruzi for a long time in axenic culture affects the differentiation capacity and the virulence of the parasite. Additionally, it was demonstrated that it is possible to maintain T. cruzi exclusively through passages in the invertebrate host.
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CONTEXT: New trial data and drug regimens that have become available in the last 2 years warrant an update to guidelines for antiretroviral therapy (ART) in human immunodeficiency virus (HIV)-infected adults in resource-rich settings. OBJECTIVE: To provide current recommendations for the treatment of adult HIV infection with ART and use of laboratory-monitoring tools. Guidelines include when to start therapy and with what drugs, monitoring for response and toxic effects, special considerations in therapy, and managing antiretroviral failure. DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION: Data that had been published or presented in abstract form at scientific conferences in the past 2 years were systematically searched and reviewed by an International Antiviral Society-USA panel. The panel reviewed available evidence and formed recommendations by full panel consensus. DATA SYNTHESIS: Treatment is recommended for all adults with HIV infection; the strength of the recommendation and the quality of the evidence increase with decreasing CD4 cell count and the presence of certain concurrent conditions. Recommended initial regimens include 2 nucleoside reverse transcriptase inhibitors (tenofovir/emtricitabine or abacavir/lamivudine) plus a nonnucleoside reverse transcriptase inhibitor (efavirenz), a ritonavir-boosted protease inhibitor (atazanavir or darunavir), or an integrase strand transfer inhibitor (raltegravir). Alternatives in each class are recommended for patients with or at risk of certain concurrent conditions. CD4 cell count and HIV-1 RNA level should be monitored, as should engagement in care, ART adherence, HIV drug resistance, and quality-of-care indicators. Reasons for regimen switching include virologic, immunologic, or clinical failure and drug toxicity or intolerance. Confirmed treatment failure should be addressed promptly and multiple factors considered. CONCLUSION: New recommendations for HIV patient care include offering ART to all patients regardless of CD4 cell count, changes in therapeutic options, and modifications in the timing and choice of ART in the setting of opportunistic illnesses such as cryptococcal disease and tuberculosis.