1,935 research outputs found
HIV Self-testing and the Missing Linkage
Rochelle Walensky and Ingrid Bassett discuss new research in <I>PLoS Medicine</I> that assessed the feasibility of home-based oral HIV self-testing in Malawi, and suggest that linkage to care must be demonstrated before the success of oral self-testing can be determined
Dithio- and Diselenophosphinate Thorium(IV) and Uranium(IV) complexes:molecular and electronic structure, spectroscopy, and transmetalation reactivity
We report a comparison of the molecular and electronic structures of dithio- and diselenophosphinate, (E2PR2)1– (E = S, Se; R = iPr, tBu), with thorium(IV) and uranium(IV) complexes. For the thorium dithiophosphinate complexes, reaction of ThCl4(DME)2 with 4 equiv of KS2PR2 (R = iPr, tBu) produced the homoleptic complexes, Th(S2PiPr2)4 (1S-Th-iPr) and Th(S2PtBu2)4 (2S-Th-tBu). The diselenophosphinate complexes were synthesized in a similar manner using KSe2PR2 to produce Th(Se2PiPr2)4 (1Se-Th-iPr) and Th(Se2PtBu2)4 (2Se-Th-tBu). U(S2PiPr2)4, 1S-U-iPr, could be made directly from UCl4 and 4 equiv of KS2PiPr2. With (Se2PiPr2)1–, using UCl4 and 3 or 4 equiv of KSe2PiPr2 yielded the monochloride product U(Se2PiPr2)3Cl (3Se-UiPr-Cl), but using UI4(1,4-dioxane)2 produced the homoleptic U(Se2PiPr2)4 (1Se-U-iPr). Similarly, the reaction of UCl4 with 4 equiv of KS2PtBu2 yielded U(S2PtBu2)4 (2S-U-tBu), whereas the reaction with KSe2PtBu2 resulted in the formation of U(Se2PtBu2)3Cl (4Se-UtBu-Cl). Using UI4(1,4-dioxane)2 and 4 equiv of KSe2PtBu2 with UCl4 in acetonitrile yielded U(Se2PtBu2)4 (2Se-U-tBu). Transmetalation reactions were investigated with complex 2Se-U-tBu and various CuX (X = Br, I) salts to yield U(Se2PtBu2)3X (6Se-UtBu-Br and 7Se-UtBu-I) and 0.25 equiv of [Cu(Se2PtBu2)]4 (8Se-Cu-tBu). Additionally, 2Se-U-tBu underwent transmetalation reactions with Hg2F2 and ZnCl2 to yield U(Se2PtBu2)3F (6) and U(Se2PtBu2)3Cl (4Se-UtBu-Cl), respectively. The molecular structures were analyzed using 1H, 13C, 31P, and 77Se NMR and IR spectroscopy and structurally characterized using X-ray crystallography. Using the QTAIM approach, the electronic structure of all homoleptic complexes was probed, showing slightly more covalent bonding character in actinide–selenium bonds over actinide–sulfur bonds
Di- and Trinuclear Mixed-Valence Copper Amidinate Complexes from Reduction of Iodine
Molecular examples of mixed-valence copper complexes through chemical oxidation are rare but invoked in the mechanism of substrate activation, especially oxygen, in copper-containing enzymes. To examine the cooperative chemistry between two metals in close proximity to each other we began studying the reactivity of a dinuclear Cu(I) amidinate complex. The reaction of [(2,6-Me2C6H3N)2C(H)]2Cu2, 1, with I2 in tetrahydrofuran (THF), CH3CN, and toluene affords three new mixed-valence copper complexes [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I3)(THF)2, 2, [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I) (NCMe)2, 3, and [(2,6-Me2C6H3N)2C(H)]3Cu3(μ3-I)2, 4, respectively. The first two compounds were characterized by UV-vis and electron paramagnetic resonance spectroscopies, and their molecular structure was determined by X-ray crystallography. Both di- and trinuclear mixed-valence intermediates were characterized for the reaction of compound 1 to compound 4, and the molecular structure of 4 was determined by X-ray crystallography. The electronic structure of each of these complexes was also investigated using density functional theory
The Evolving Landscape of the Economics of HIV Treatment and Prevention
Bohdan Nosyk and Julio Montaner argue that the cost-effectiveness of HAART roll out has been significantly underestimated because economic analyses haven't yet taken into account the beneficial impact of HAART on HIV transmission
Characterization of a core fragment of the rhesus monkey TRIM5α protein
<p>Abstract</p> <p>Background</p> <p>Like all tripartite motif (TRIM) proteins, the retroviral restriction factor TRIM5α consists of RING, B-box 2 and coiled-coil domains, with a C-terminal B30.2(SPRY) domain. Although structures have been determined for some individual TRIM domains, the structure of an intact TRIM protein is unknown.</p> <p>Results</p> <p>Here, we express and characterize a protease-resistant 29-kD core fragment containing the B-box 2, coiled coil and adjacent linker (L2) region of TRIM5α. This BCCL2 protein formed dimers and higher-order oligomers in solution. Approximately 40% of the BCCL2 secondary structure consisted of alpha helices. Partial loss of alpha-helical content and dissociation of dimers occurred at 42°C, with the residual alpha helices remaining stable up to 80°C.</p> <p>Conclusions</p> <p>These results indicate that the B-box 2, coiled-coil and linker 2 regions of TRIM5α form a core dimerization motif that exhibits a high level of alpha-helical content.</p
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Reduction of CO2 and CS2 with Uranium(III) Metallocene Aryloxides
The reactivity of two metallocene aryloxide U(III) complexes, [(C5Me5)2U(O-Ar)], Ar = 4-tBuC6H4, 1; Ar = 2,6-tBu2-4-CH3C6H2(BHT), 3, with CO2and CS2has been investigated. The reaction of 1 with CO2produces a bridging oxo complex, [{(C5Me5)2(4-tBuC6H4-O)U}2(μ2-O)], 4, while 3 with CO2results in reductive disproportionation to form the bridging carbonate species, [{(C5Me5)2(BHT)U}2(μ2-κ2:η1-CO3)], 5. The difference in reactivity can be attributed to the steric properties of the ligand because the reaction of 3 with an oxo-delivering agent yields a U(V) terminal oxo complex, [(C5Me5)2(BHT)U═O], 6. Reduction of CS2to form a bridging (CS2)2-ligand, [{(C5Me5)2(tBuC6H4-O)U}2(μ2-CS2)], 7, is observed with 1, while the reaction of 3 with CS2also produces a bridging (CS2)2-reduced ligand complex, followed by C-H bond activation of a methyl group from one (C5Me5)1-ring, [(C5Me5)2(BHT)U{μ2-C(H)S2}U(C5Me4CH2)(C5Me5)(BHT)], 8. All compounds are characterized by NMR and IR spectroscopy, and their solid-state structures are determined by X-ray crystallography
The "ART" of Linkage: Pre-Treatment Loss to Care after HIV Diagnosis at Two PEPFAR Sites in Durban, South Africa
BACKGROUND. Although loss to follow-up after antiretroviral therapy (ART) initiation is increasingly recognized, little is known about pre-treatment losses to care (PTLC) after an initial positive HIV test. Our objective was to determine PTLC in newly identified HIV-infected individuals in South Africa. METHODOLOGY/PRINCIPAL FINDINGS. We assembled the South African Test, Identify and Link (STIAL) Cohort of persons presenting for HIV testing at two sites offering HIV and CD4 count testing and HIV care in Durban, South Africa. We defined PTLC as failure to have a CD4 count within 8 weeks of HIV diagnosis. We performed multivariate analysis to identify factors associated with PTLC. From November 2006 to May 2007, of 712 persons who underwent HIV testing and received their test result, 454 (64%) were HIV-positive. Of those, 206 (45%) had PTLC. Infected patients were significantly more likely to have PTLC if they lived =10 kilometers from the testing center (RR=1.37; 95% CI: 1.11-1.71), had a history of tuberculosis treatment (RR=1.26; 95% CI: 1.00-1.58), or were referred for testing by a health care provider rather than self-referred (RR=1.61; 95% CI: 1.22-2.13). Patients with one, two or three of these risks for PTLC were 1.88, 2.50 and 3.84 times more likely to have PTLC compared to those with no risk factors. CONCLUSIONS/SIGNIFICANCE. Nearly half of HIV-infected persons at two high prevalence sites in Durban, South Africa, failed to have CD4 counts following HIV diagnosis. These high rates of pre-treatment loss to care highlight the urgent need to improve rates of linkage to HIV care after an initial positive HIV test.US National Institute of Allergy and Infectious Diseases (R01 AI058736, K24 AI062476, K23 AI068458); the Harvard University Center for AIDS Research (P30 AI42851); National Institutes of Health (K24 AR 02123); the Doris Duke Charitable Foundation (Clinical Scientist Development Award); the Harvard University Program on AID
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Natural history of colonization with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE): a systematic review
Background: No published systematic reviews have assessed the natural history of colonization with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE). Time to clearance of colonization has important implications for patient care and infection control policy. Methods: We performed parallel searches in OVID Medline for studies that reported the time to documented clearance of MRSA and VRE colonization in the absence of treatment, published between January 1990 and July 2012. Results: For MRSA, we screened 982 articles, identified 16 eligible studies (13 observational studies and 3 randomized controlled trials), for a total of 1,804 non-duplicated subjects. For VRE, we screened 284 articles, identified 13 eligible studies (12 observational studies and 1 randomized controlled trial), for a total of 1,936 non-duplicated subjects. Studies reported varying definitions of clearance of colonization; no study reported time of initial colonization. Studies varied in the frequency of sampling, assays used for sampling, and follow-up period. The median duration of total follow-up was 38 weeks for MRSA and 25 weeks for VRE. Based on pooled analyses, the model-estimated median time to clearance was 88 weeks after documented colonization for MRSA-colonized patients and 26 weeks for VRE-colonized patients. In a secondary analysis, clearance rates for MRSA and VRE were compared by restricting the duration of follow-up for the MRSA studies to the maximum observed time point for VRE studies (43 weeks). With this restriction, the model-fitted median time to documented clearance for MRSA would occur at 41 weeks after documented colonization, demonstrating the sensitivity of the pooled estimate to length of study follow-up. Conclusions: Few available studies report the natural history of MRSA and VRE colonization. Lack of a consistent definition of clearance, uncertainty regarding the time of initial colonization, variation in frequency of sampling for persistent colonization, assays employed and variation in duration of follow-up are limitations of the existing published literature. The heterogeneity of study characteristics limits interpretation of pooled estimates of time to clearance, however, studies included in this review suggest an increase in documented clearance over time, a result which is sensitive to duration of follow-up
Global Health Training in U.S. Graduate Psychiatric Education
Objective—Global health training opportunities have figured prominently into medical students’ residency program choices across a range of clinical specialties. To date, however, the national scope of global mental health education has not heretofore been systematically assessed. We therefore sought to characterize the distribution of global health training opportunities in U.S. graduate psychiatric education.
Methods—We examined the web pages of all U.S. psychiatry residency training programs, along with search results from a systematic Google query designed to identify global health training opportunities.
Results—Of the 183 accredited U.S. psychiatry residency programs, we identified 17 programs (9.3%) offering 28 global health training opportunities in 64 countries. Ten psychiatry residency programs offered their residents opportunities to participate in one or more elective-based rotations, eight offered research activities, and six offered extended field-based training. Most global health training opportunities occurred within the context of externally administered, institution-wide initiatives generally available to residents from a range of clinical specialties, rather than within internally administered departmental initiatives specifically tailored for psychiatry residents.
Conclusions—There are relatively few global health training opportunities in U.S. graduate psychiatric education. These activities have a clear role in enhancing mastery of Accreditation Council for Graduate Medical Education core competencies, but important challenges related to program funding and evaluation remain
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