904 research outputs found

    Cross-reactivity between HLA-A2-restricted FLU-M1:58–66 and HIV p17 GAG:77–85 epitopes in HIV-infected and uninfected individuals

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    BACKGROUND: The matrix protein of the influenza A virus and the matrix and capsid proteins of the human immunodeficiency virus (HIV) share striking structural similarities which may have evolutionary and biological significance. These similarities led us to hypothesize the existence of cross-reactivity between HLA-A2-restricted FLU-M1:58–66 and HIV-1 p17 GAG:77–85 epitopes. METHODS: The hypothesis that these two epitopes are cross-reactive was tested by determining the presence and extent of FLU/GAG immune cross-reactivity in lymphocytes from HIV-seropositive and seronegative HLA-A2(+ )donors by cytotoxicity assays and tetramer analyses. Moreover, the molecular basis for FLU/GAG cross-reactivity in HIV-seropositive and seronegative donors was studied by comparing lymphocyte-derived cDNA sequences corresponding to the TCR-β variable regions, in order to determine whether stimulation of lymphocytes with either peptide results in the expansion of identical T-cell clonotypes. RESULTS: Here, we report evidence of cross-reactivity between FLU-M1:58–66 and HIV-1 p17 GAG:77–85 epitopes following in vitro stimulation of PBMC derived from either HIV-seropositive or seronegative HLA-A2(+ )donors as determined by cytotoxicity assays, tetramer analyses, and molecular clonotyping. CONCLUSION: These results suggest that immunity to the matrix protein of the influenza virus may drive a specific immune response to an HLA-A2-restricted HIV gag epitope in HIV-infected and uninfected donors vaccinated against influenza

    Factors predictive of successful retention in care among HIV-infected men in a universal test-and-treat setting in Uganda and Kenya: A mixed methods analysis.

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    BackgroundPrevious research indicates clinical outcomes among HIV-infected men in sub-Saharan Africa are sub-optimal. The SEARCH test and treat trial (NCT01864603) intervention included antiretroviral care delivery designed to address known barriers to HIV-care among men by decreasing clinic visit frequency and providing flexible, patient-centered care with retention support. We sought to understand facilitators and barriers to retention in care in this universal treatment setting through quantitative and qualitative data analysis.MethodsWe used a convergent mixed methods study design to evaluate retention in HIV care among adults (age > = 15) during the first year of the SEARCH (NCT01864603) test and treat trial. Cox proportional hazards regression was used to evaluate predictors of retention in care. Longitudinal qualitative data from n = 190 in-depth interviews with HIV-positive individuals and health care providers were analyzed to identify facilitators and barriers to HIV care engagement.ResultsThere were 1,863 men and 3,820 women who linked to care following baseline testing. Retention in care was 89.7% (95% CI 87.0-91.8%) among men and 89.0% (86.8-90.9%) among women at one year. In both men and women older age was associated with higher rates of retention in care at one year. Additionally, among men higher CD4+ at ART initiation and decreased time between testing and ART initiation was associated with higher rates of retention. Maintaining physical health, a patient-centered treatment environment, supportive partnerships, few negative consequences to disclosure, and the ability to seek care in facilities outside of their community of residence were found to promote retention in care.ConclusionsFeatures of the ART delivery system in the SEARCH intervention and social and structural advantages emerged as facilitators to retention in HIV care among men. Messaging around the health benefits of early ART start, decreasing logistical barriers to HIV care, support of flexible treatment environments, and accelerated linkage to care, are important to men's success in ART treatment programs. Men already benefit from increased social support following disclosure of their HIV-status. Future efforts to shift gender norms towards greater equity are a potential strategy to support high levels of engagement in care for both men and women

    Large deletion mutations involving the first pyrimidine-rich tract of the 5' nontranslated RNA of human hepatitis A virus define two adjacent domains associated with distinct replication phenotypes.

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    The 5' nontranslated RNA (5'NTR) of the HM175 strain of human hepatitis A virus contains several pyrimidine-rich regions, the largest and most 5' of which (pYl) is an almost pure polypyrimidine tract located between nucleotides (nt) 99 and 138, which includes five tandem repeats of the sequence motif (U)UUCC(C). Previous modeling of the RNA secondary structure suggested that this region was likely to be single-stranded, but repetitive RNase Vl cleavage sites within these (U)UUCC(C) motifs indicated that pYl possesses an ordered structure. To assess the role of this domain in replication of the virus, a series of large deletion mutations were created which involved the pYl domain of an infectious cDNA clone. Deletion of 44 nt between nt 96 and 139, including the entire pYl domain, did not reduce the capacity of the virus to replicate in BS-C-1 or FRhK-4 cells, as assessed by the size of replication foci in radioimmunofocus assays or by virus yields under one-step growth conditions. In contrast, viable virus could not be recovered from transfected RNAs in which the deletion was extended in a 5' direction by an additional 3 nt (A93-134), most likely because of the destabilization of a predicted stem-loop structure upstream of pYl. Deletion mutations extending in a 3' fashion to nt 140, 141, or 144 resulted in moderately (A96-140 and A96-141) or strongly (A99-144, A116-144, and A131-144) temperature-sensitive replication phenotypes. Although deletion of the pYl domain did not by itself affect the replication phenotype of virus, the additional deletion of sequence elements within the pYl domain (nt 99 to 130) substantially enhanced the temperature-sensitive phenotype of A131-144 virus. These data suggest that the (U)UUCC(C) motifs within the pYl domain are conserved among wild-type viruses in order to serve a function required during infection in vivo but not in cell culture. In contrast, the single-stranded region located immediately downstream of pYl (nt 140 to 144) is essential for efficient replication in cultured cells at physiological temperature. Viruses with deletion mutations involving nt 140 to 144 and viruses with large pYl deletions but normal replication phenotypes in cell culture may have attenuation properties which could be exploited for vaccine development

    In vitro characterization of an internal ribosomal entry site (IRES) present within the 5' nontranslated region of hepatitis A virus RNA: comparison with the IRES of encephalomyocarditis virus.

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    The lengthy 5' nontranslated region (5'NTR) of hepatitis A virus (HAV) forms a highly ordered secondary structure, which has been suggested to play an important role in controlling viral translation by allowing for translation initiation by internal ribosome entry. To test this hypothesis, synthetic bicistronic RNAs, with all or part of the HAV 5'NTR in the intercistronic space, were translated in rabbit reticulocyte lysates. In the presence of an upstream cistron designed to block ribosomal scanning, the HAV 5'NTR was capable of directing the internal initiation of translation, confirming the presence of an internal ribosome entry site (IRES). Analysis of various deletion mutants demonstrated that the 5' border of the IRES is located between nucleotides 151 and 257, while the 3' border extends to the 3' end of the 5'NTR, between nucleotide 695 and the first initiation codon at 735. Except for a segment between bases 638 and 694, deletion of stem-loop structures between bases 151 and the 3' end of the 5'NTR inhibited or abolished translation. The addition of a 5' cap structure (m7GpppN) to monocistronic or bicistronic transcripts decreased the translation of a reporter gene downstream of the HAV 5'NTR but enhanced translation of the upstream cistron in bicistronic transcripts. This finding indicates that a 5' cap structure is inhibitory to HAV IRES-directed translation initiation and that the cap structure and the HAV IRES probably compete for the same limiting translation factors. The efficiency with which monocistronic constructs containing the HAV 5'NTR directed translation in reticulocyte lysates was compared with results for monocistronic constructs containing the IRES of the more rapidly growing encephalomyocarditis virus (EMCV). These results indicated that the HAV 5'NTR was more than 25-fold less active than the EMCV IRES in producing translation product. HAV 5'NTR-directed translation was inhibited by the presence of a one-fifth molar quantity of RNA containing the EMCV IRES, while a fivefold molar excess of the HAV 5'NTR did not inhibit EMCV IRES-directed translation. The relatively weak activity of the HAV IRES may thus be due to a reduced affinity for cellular translation factors which are present in limiting quantities in rabbit reticulocyte lysate

    Computer Administered Safety Planning for Individuals at Risk for Suicide: Development and Usability Testing

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    BACKGROUND: Safety planning is a brief intervention that has become an accepted practice in many clinical settings to help prevent suicide. Even though it is quick compared to other approaches, it frequently requires 20 min or more to complete, which can impede adoption. A self-administered, Web-based safety planning application could potentially reduce clinician time, help promote standardization and quality, and provide enhanced ability to share the created plan. OBJECTIVE: The aim of this study was to design, build, and test the usability of a Web-based, self-administered safety planning application. METHODS: We employed a user-centered software design strategy led by a multidisciplinary team. The application was tested for usability with a target sample of suicidal patients. Detailed observations, structured usability ratings, and Think Aloud procedures were used. Suicidal ideation intensity and perceived ability to cope were assessed pre-post engagement with the Web application. RESULTS: A total of 30 participants were enrolled. Usability ratings were generally strong, and all patients successfully built a safety plan. However, the completeness of the safety plan varied. The mean number of steps completed was 5.5 (SD 0.9) out of 6, with 90% (27/30) of participants completing at least 5 steps and 67% (20/30) completing all 6 steps. Some safety planning steps were viewed as inapplicable to some individuals. Some confusion in instructions led to modifications to improve understandability of each step. Ratings of suicide intensity after completion of the application were significantly lower than preratings, pre: mean 5.11 (SD 2.9) versus post: mean 4.46 (SD 3.0), t27=2.49, P=.02. Ratings of ability to cope with suicidal thoughts after completion of the application were higher than preratings, with the difference approaching statistical significance, pre: mean 5.93 (SD 2.9), post: mean 6.64 (SD 2.4), t27=-2.03, P=.05. CONCLUSIONS: We have taken the first step toward identifying the components needed to maximize usability of a self-administered, Web-based safety planning application. Results support initial consideration of the application as an adjunct to clinical contact. This allows for the clinician or other personnel to provide clarification, when needed, to help the patient build the plan, and to help review and revise the draft

    MatchPoint:Spontaneous Spatial Coupling of Body Movement for Touchless Pointing

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    Pointing is a fundamental interaction technique where user movement is translated to spatial input on a display. Conventionally, this is based on a rigid configuration of a display coupled with a pointing device that determines the types of movement that can be sensed, and the specific ways users can affect pointer input. Spontaneous spatial coupling is a novel input technique that instead allows any body movement, or movement of tangible objects, to be appropriated for touchless pointing on an ad hoc basis. Pointer acquisition is facilitated by the display presenting graphical objects in motion, to which users can synchronise to define a temporary spatial coupling with the body part or tangible object they used in the process. The technique can be deployed using minimal hardware, as demonstrated by MatchPoint, a generic computer vision-based implementation of the technique that requires only a webcam. We explore the design space of spontaneous spatial coupling, demonstrate the versatility of the technique with application examples, and evaluate MatchPoint performance using a multi-directional pointing task

    U-Pb and Hf Isotopic Evidence for an Arctic Origin of Terranes in Northwestern Washington

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    New field, U-Pb, and Lu-Hf zircon data constrain the geologic history, age, and origin of the Yellow Aster Complex (YAC) in northwestern Washington, providing insight into the tectonic history of this and related Paleozoic arc terranes of the western North American Cordillera. Mapping shows that the oldest YAC rocks consist of quartzofeldspathic paragneiss (meta-arkose) and quartzose calc-silicate paragneiss (metacalcareous siltstone) in gradational contact. Paragneisses are cut by syn-tectonic and post-tectonic intrusions and faulted against granitic orthogneiss. U-Pb zircon results show that (1) maximum depositional ages of paragneisses are Silurian to Early Devonian (432– 390 Ma); (2) detrital zircons from quartzose calc-silicate paragneisses show a broad age peak from 1900 to 1000 Ma, while quartzofeldspathic paragneisses contain several distinct Precambrian age peaks, including at 2.0–1.8 Ga and 2.5–2.4 Ga; (3) paragneisses contain early Paleozoic grains with peaks ca. 420–400 and ca. 460–440 Ma; (4) pre-tectonic orthogneiss and syn-tectonic and post-tectonic dikes range from ca. 410–406 Ma; and (5) intrusive rocks contain apparently xenocrystic ca. 480–440 Ma grains. Lu-Hf isotope data show that nearly all Paleozoic zircons have negative εHf(t) values, and zircons in the meta-arkose samples are more negative than those in the calc-silicate. Zircons in several meta-arkose samples yield εHf(t) values of –40 to –57, rare in the North American Cordillera, and requires the involvement of Mesoarchean to Eoarchean crustal components. The most likely source region with crust as old as Eoarchean and early Paleozoic magmatism is the Greenland Caledonides, which implies derivation from the Arctic margin of northeastern Laurentia or Baltica. The chemistry and petrology of the igneous rocks suggest that the terrane was in a continental arc setting before, during, and after deposition of the sedimentary rocks. The data constrain deformation, metamorphism, and magmatism in the YAC to a brief period in the Early Devonian, from ca. 410 to 400 Ma. Age and Hf patterns of the YAC are similar to elements of the Yukon-Tanana and Alexander terranes. Our study shows that the complex history of metamorphosed terranes requires analysis of multiple isotopic and petrologic proxies, and U-Pb analysis of both igneous (n = 50) and detrital (n = 400) zircons to confirm or refute terrane and provenance correlations
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