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1.
Sci Adv ; 8(49): eadd2191, 2022 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-36490335

RESUMEN

SARS-CoV-2, a human coronavirus, is the causative agent of the COVID-19 pandemic. Its genome is translated into two large polyproteins subsequently cleaved by viral papain-like protease and main protease (Mpro). Polyprotein processing is essential yet incompletely understood. We studied Mpro-mediated processing of the nsp7-11 polyprotein, whose mature products include cofactors of the viral replicase, and identified the order of cleavages. Integrative modeling based on mass spectrometry (including hydrogen-deuterium exchange and cross-linking) and x-ray scattering yielded a nsp7-11 structural ensemble, demonstrating shared secondary structural elements with individual nsps. The pattern of cross-links and HDX footprint of the C145A Mpro and nsp7-11 complex demonstrate preferential binding of the enzyme active site to the polyprotein junction sites and additional transient contacts to help orient the enzyme on its substrate for cleavage. Last, proteolysis assays were used to characterize the effect of inhibitors/binders on Mpro processing/inhibition using the nsp7-11 polyprotein as substrate.

2.
BMJ Open ; 12(8): e061369, 2022 08 25.
Artículo en Inglés | MEDLINE | ID: mdl-36008061

RESUMEN

OBJECTIVE: To explore the causes and levels of moral distress experienced by clinicians caring for the low-income patients of safety net practices in the USA during the COVID-19 pandemic. DESIGN: Cross-sectional survey in late 2020, employing quantitative and qualitative analyses. SETTING: Safety net practices in 20 US states. PARTICIPANTS: 2073 survey respondents (45.8% response rate) in primary care, dental and behavioural health disciplines working in safety net practices and participating in state and national education loan repayment programmes. MEASURES: Ordinally scaled degree of moral distress experienced during the pandemic, and open-ended response descriptions of issues that caused most moral distress. RESULTS: Weighted to reflect all surveyed clinicians, 28.4% reported no moral distress related to work during the pandemic, 44.8% reported 'mild' or 'uncomfortable' levels and 26.8% characterised their moral distress as 'distressing', 'intense' or 'worst possible'. The most frequently described types of morally distressing issues encountered were patients not being able to receive the best or needed care, and patients and staff risking infection in the office. Abuse of clinic staff, suffering of patients, suffering of staff and inequities for patients were also morally distressing, as were politics, inequities and injustices within the community. Clinicians who reported instances of inequities for patients and communities and the abuse of staff were more likely to report higher levels of moral distress. CONCLUSIONS: During the pandemic's first 9 months, moral distress was common among these clinicians working in US safety net practices. But for only one-quarter was this significantly distressing. As reported for hospital-based clinicians during the pandemic, this study's clinicians in safety net practices were often morally distressed by being unable to provide optimal care to patients. New to the literature is clinicians' moral distress from witnessing inequities and other injustices for their patients and communities.


Asunto(s)
COVID-19 , COVID-19/epidemiología , Estudios Transversales , Humanos , Principios Morales , Pandemias , Encuestas y Cuestionarios
3.
Sci Adv ; 8(27): eabn9874, 2022 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-35857464

RESUMEN

Key proteins of retroviruses and other RNA viruses are translated and subsequently processed from polyprotein precursors by the viral protease (PR). Processing of the HIV Gag-Pol polyprotein yields the HIV structural proteins and enzymes. Structures of the mature enzymes PR, reverse transcriptase (RT), and integrase (IN) aided understanding of catalysis and design of antiretrovirals, but knowledge of the Pol precursor architecture and function before PR cleavage is limited. We developed a system to produce stable HIV-1 Pol and determined its cryo-electron microscopy structure. RT in Pol has a similar arrangement to the mature RT heterodimer, and its dimerization may draw together two PR monomers to activate proteolytic processing. HIV-1 thus may leverage the dimerization interfaces in Pol to regulate assembly and maturation of polyprotein precursors.

4.
Public Health Rep ; 137(1): 149-162, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34694922

RESUMEN

OBJECTIVES: The impact of the COVID-19 pandemic has been particularly harsh for low-income and racial and ethnic minority communities. It is not known how the pandemic has affected clinicians who provide care to these communities through safety-net practices, including clinicians participating in the National Health Service Corps (NHSC). METHODS: In late 2020, we surveyed clinicians who were serving in the NHSC as of July 1, 2020, in 20 states. Clinicians reported on work and job changes and their current well-being, among other measures. Analyses adjusted for differences in subgroup response rates and clustering of clinicians within practices. RESULTS: Of 4263 surveyed clinicians, 1890 (44.3%) responded. Work for most NHSC clinicians was affected by the pandemic, including 64.5% whose office visit numbers fell by half and 62.5% for whom most visits occurred virtually. Fewer experienced changes in their jobs; for example, only 14.9% had been furloughed. Three-quarters (76.6%) of these NHSC clinicians scored in at-risk levels for their well-being. Compared with primary care and behavioral health clinicians, dental clinicians much more often had been furloughed and had their practices close temporarily. CONCLUSIONS: The pandemic has disrupted the work, jobs, and mental health of NHSC clinicians in ways similar to its reported effects on outpatient clinicians generally. Because clinicians' mental health worsens after a pandemic, which leads to patient disengagement and job turnover, national programs and policies should help safety-net practices build cultures that support and give greater priority to clinicians' work, job, and mental health needs now and before the next pandemic.


Asunto(s)
Actitud del Personal de Salud , COVID-19/epidemiología , Área sin Atención Médica , Salud Mental , Proveedores de Redes de Seguridad/organización & administración , Adulto , Femenino , Estado de Salud , Humanos , Satisfacción en el Trabajo , Masculino , Persona de Mediana Edad , Salud Laboral , Pandemias , SARS-CoV-2 , Estrés Psicológico/epidemiología , Estados Unidos/epidemiología
5.
Viruses ; 13(8)2021 07 29.
Artículo en Inglés | MEDLINE | ID: mdl-34452360

RESUMEN

In most cases, proteolytic processing of the retroviral Pol portion of the Gag-Pol polyprotein precursor produces protease (PR), reverse transcriptase (RT), and integrase (IN). However, foamy viruses (FVs) express Pol separately from Gag and, when Pol is processed, only the IN domain is released. Here, we report a 2.9 Å resolution crystal structure of the mature PR-RT from prototype FV (PFV) that can carry out both proteolytic processing and reverse transcription but is in a configuration not competent for proteolytic or polymerase activity. PFV PR-RT is monomeric and the architecture of PFV PR is similar to one of the subunits of HIV-1 PR, which is a dimer. There is a C-terminal extension of PFV PR (101-145) that consists of two helices which are adjacent to the base of the RT palm subdomain, and anchors PR to RT. The polymerase domain of PFV RT consists of fingers, palm, thumb, and connection subdomains whose spatial arrangements are similar to the p51 subunit of HIV-1 RT. The RNase H and polymerase domains of PFV RT are connected by flexible linkers. Significant spatial and conformational (sub)domain rearrangements are therefore required for nucleic acid binding. The structure of PFV PR-RT provides insights into the conformational maturation of retroviral Pol polyproteins.


Asunto(s)
Péptido Hidrolasas/química , Poliproteínas/química , ADN Polimerasa Dirigida por ARN/química , Spumavirus/química , Cristalización , Péptido Hidrolasas/metabolismo , Poliproteínas/metabolismo , ADN Polimerasa Dirigida por ARN/metabolismo , Transcripción Reversa
6.
J Am Soc Mass Spectrom ; 32(7): 1618-1630, 2021 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-34121407

RESUMEN

Coronavirus (CoV) nonstructural proteins (nsps) assemble to form the replication-transcription complex (RTC) responsible for viral RNA synthesis. nsp7 and nsp8 are important cofactors of the RTC, as they interact and regulate the activity of RNA-dependent RNA polymerase and other nsps. To date, no structure of the full-length SARS-CoV-2 nsp7:nsp8 complex has been published. The current understanding of this complex is based on structures from truncated constructs, with missing electron densities, or from related CoV species where SARS-CoV-2 nsp7 and nsp8 share upward of 90% sequence identity. Despite available structures solved using crystallography and cryo-EM representing detailed static snapshots of the nsp7:nsp8 complex, it is evident that the complex has a high degree of structural plasticity. However, relatively little is known about the conformational dynamics of the individual proteins and how they complex to interact with other nsps. Here, the solution-based structural proteomic techniques, hydrogen-deuterium exchange mass spectrometry (HDX-MS) and cross-linking mass spectrometry (XL-MS), illuminate the dynamics of SARS-CoV-2 full-length nsp7 and nsp8 proteins and the nsp7:nsp8 protein complex. Results presented from the two techniques are complementary and validate the interaction surfaces identified from the published three-dimensional heterotetrameric crystal structure of the SARS-CoV-2 truncated nsp7:nsp8 complex. Furthermore, mapping of XL-MS data onto higher-order complexes suggests that SARS-CoV-2 nsp7 and nsp8 do not assemble into a hexadecameric structure as implied by the SARS-CoV full-length nsp7:nsp8 crystal structure. Instead, our results suggest that the nsp7:nsp8 heterotetramer can dissociate into a stable dimeric unit that might bind to nsp12 in the RTC without significantly altering nsp7-nsp8 interactions.


Asunto(s)
ARN Polimerasa Dependiente de ARN de Coronavirus/química , Proteómica/métodos , Proteínas no Estructurales Virales/química , COVID-19/virología , ARN Polimerasa Dependiente de ARN de Coronavirus/genética , ARN Polimerasa Dependiente de ARN de Coronavirus/metabolismo , Humanos , Espectrometría de Masas de Intercambio de Hidrógeno-Deuterio , Modelos Moleculares , Conformación Proteica , SARS-CoV-2/química , Proteínas no Estructurales Virales/genética , Proteínas no Estructurales Virales/metabolismo
7.
bioRxiv ; 2021 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-33688660

RESUMEN

Coronavirus (CoV) non-structural proteins (nsps) assemble to form the replication-transcription complex (RTC) responsible for viral RNA synthesis. nsp7 and nsp8 are important cofactors of the RTC, as they interact and regulate the activity of RNA-dependent RNA polymerase (RdRp) and other nsps. To date, no structure of full-length SARS-CoV-2 nsp7:nsp8 complex has been published. Current understanding of this complex is based on structures from truncated constructs or with missing electron densities and complexes from related CoV species with which SARS-CoV-2 nsp7 and nsp8 share upwards of 90% sequence identity. Despite available structures being solved using crystallography and cryo-EM representing detailed snapshots of the nsp7:nsp8 complex, it is evident that the complex has a high degree of structural plasticity. However, relatively little is known about the conformational dynamics of the complex and how it assembles to interact with other nsps. Here, the solution-based structural proteomic techniques, hydrogen-deuterium exchange mass spectrometry (HDX-MS) and crosslinking mass spectrometry (XL-MS), illuminate the structural dynamics of the SARS-CoV-2 full-length nsp7:nsp8 complex. The results presented from the two techniques are complementary and validate the interaction surfaces identified from the published three-dimensional heterotetrameric crystal structure of SARS-CoV-2 truncated nsp7:nsp8 complex. Furthermore, mapping of XL-MS data onto higher order complexes suggests that SARS-CoV-2 nsp7 and nsp8 do not assemble into a hexadecameric structure as implied by the SARS-CoV full-length nsp7:nsp8 crystal structure. Instead our results suggest that the nsp7:nsp8 heterotetramer can dissociate into a stable dimeric unit that might bind to nsp12 in the RTC without altering nsp7-nsp8 interactions.

8.
Conserv Biol ; 35(1): 168-178, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-32277780

RESUMEN

During 2021, Parties to the Convention on Biological Diversity (CBD) are expected to meet in Kunming, China, to agree on a new global biodiversity framework aimed at halting and reversing biodiversity loss, encouraging the sustainable use of biodiversity, and ensuring the equitable sharing of its benefits. As the post-2020 global biodiversity framework evolves, parties to the convention are being exposed to a range of perspectives on the conservation and sustainable use of biodiversity, relating to the future framework as a whole or to aspects of it. Area-based conservation measures are one such aspect, and there are diverse perspectives on how new targets might be framed in relation to these measures. These perspectives represent different outlooks on the relationship between human and nonhuman life on Earth. However, in most cases there is a lack of clarity on how they would be implemented in practice, the implications this would have for biodiversity and human well-being, and how they would contribute to achieving the 2050 Vision for Biodiversity of "living in harmony with nature." We sought to clarify these issues by summarizing some of these perspectives in relation to the future of area-based biodiversity conservation. We identified these perspectives through a review of the literature and expert consultation workshops and compiled them into 4 main groups: Aichi+, ambitious area-based conservation perspectives, new conservation, and whole-earth conservation. We found that although the perspectives Aichi+ and whole earth are in some cases at odds with one another, they also have commonalities, and all perspectives have elements that can contribute to developing and implementing the post-2020 global biodiversity framework and achieving the longer term CBD 2050 Vision.


Perspectivas de la Conservación Basada en el Área y su Significado para las Futuras Políticas de Biodiversidad Resumen Durante 2021, se espera que las partes miembro del Convenio sobre la Diversidad Biológica (CBD) se reúnan en Kunming, China, para acordar un nuevo marco de trabajo global para la biodiversidad enfocado en detener y revertir la pérdida de la biodiversidad, promover el uso sustentable de la biodiversidad y asegurar la repartición equitativa de sus beneficios. Conforme evoluciona el marco de trabajo global para la biodiversidad post-2020, las partes miembro del convenio están conociendo una gama de perspectivas de la conservación y el uso sustentable de la biodiversidad, relacionándolas con el futuro marco de trabajo en su totalidad o sólo con algunos aspectos del marco de trabajo. Las medidas de conservación basadas en el área son uno de dichos aspectos y existen diversas perspectivas sobre cómo los nuevos objetivos podrían estar enmarcados en relación a estas medidas. Estas perspectivas representan diferentes puntos de vista sobre la relación entre la vida humana y no humana en la Tierra. Sin embargo, en la mayoría de los casos existe una falta de claridad sobre cómo se implementarían en la práctica, las implicaciones que ésto tendría para la biodiversidad y el bienestar humano y cómo contribuirían para alcanzar la Visión para la Biodiversidad 2050 de "vivir en armonía con la naturaleza". Buscamos aclarar estos temas al resumir algunas de estas perspectivas en relación al futuro de la conservación de la biodiversidad basada en el área. Identificamos estas perspectivas por medio de una revisión de la literatura y talleres de consulta a expertos y las compilamos en cuatro grupos principales: Aichi+, perspectivas ambiciosas de conservación basada en el área, conservación nueva y conservación del mundo entero. Descubrimos que aunque las perspectivas Aichi+ y conservación del mundo entero entran en conflicto en algunos casos, también tienen puntos comunes, y todas las perspectivas tienen elementos que pueden contribuir al desarrollo e implementación del marco de trabajo global para la biodiversidad post-2020 y para alcanzar la Visión CBD 2050 de mayor plazo.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales , China , Humanos , Políticas
9.
J Mol Model ; 26(11): 305, 2020 Oct 17.
Artículo en Inglés | MEDLINE | ID: mdl-33068160

RESUMEN

The mechanisms of LMnO3 (L = O-, Cl, NPH3, CH3, and Cp)-catalyzed oxidation of ethyne has been studied on the singlet and triplet hypersurfaces at the M06/6-311G(d) level of theory. For the first step, the [3 + 2] pathways to the formation of the metalla-2,5-dioxol-3-ene intermediate are kinetically and thermodynamically the most favored pathways in all the complexes studied; it is favored over the [2 + 2] addition pathways to the metallaoxetene intermediate. The formation of the oxirene precursor that could give the oxirene the reported key intermediates in the ozonolysis of alkynes would most likely result from the oxidation of ethyne by MnO3Cl on the triplet potential energy surface (PES). [3 + 2] versus [2 + 1] addition of MnO3Cl with ethyne at the M06/6-311G(d) level of theory.

10.
Rural Remote Health ; 20(3): 5494, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32646221

RESUMEN

INTRODUCTION: In Eswatini in Southern Africa, rural populations experience unnecessary snakebite-inflicted injuries and deaths. Children are at the highest risk because of their small size and curious nature. This qualitative study explores the current knowledge and attitudes about snakebite, and the perceptions of a musical intervention, titled Iculo ngenyoka ('Snake song' in Zulu), as an educational tool aimed to raise awareness about snakes in the Lubombo region, Eswatini. METHODS: Semi-structured interviews with community members (n=56), parents/guardians/key informant (n=11) and children aged 7-17 years (n=45) were conducted between May and June 2018. Participants were selected from four communities within the Lubombo region. Data were analyzed using a framework analysis approach. RESULTS: The current sources of snake education evolved from information learned in the homesteads, schools, and through personal experiences. The majority of interviewees perceived music as a culturally appropriate, engaging and memorable method to learn about snakes. Iculo ngenyoka was perceived as an effective tool to raise awareness about snakes in the community. CONCLUSION: This study is the first to explore the importance of musical interventions in educating vulnerable communities about snakes. The Iculo ngenyoka song offers a portable medium for communicating messages about snakebite prevention, affirming the value of snakebite awareness and promoting cooperative efforts to address the burden of snakebite envenoming in the region. The results emphasize the demand for education and the potential use of Iculo ngenyoka and similar musical tools to raise awareness about snakebite in Eswatini. Re-translation and other customizations of structured musical education tools for children could be applied broadly if shown to be effective.


Asunto(s)
Protección a la Infancia/estadística & datos numéricos , Educación en Salud/métodos , Música , Población Rural/estadística & datos numéricos , Mordeduras de Serpientes/prevención & control , Adolescente , Adulto , Animales , Niño , Esuatini , Femenino , Humanos , Masculino , Proyectos Piloto , Serpientes
11.
Conserv Biol ; 33(4): 821-831, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-30461056

RESUMEN

Eight conventions make up the biodiversity cluster of multilateral environmental agreements (MEAs) that provide the critical international legal framework for the conservation and sustainable use of nature. However, concerns about the rate of implementation of the conventions at the national level have triggered discussions about the effectiveness of these MEAs in halting the loss of biodiversity. Two main concerns have emerged: lack of capacity and resources and lack of coherence in implementing multiple conventions. We focused on the latter and considered the mechanisms by which international conventions are translated into national policy. Specifically, we examined how the Strategic Plan for Biodiversity 2011-2020 and the associated Aichi Biodiversity Targets have functioned as a unifying grand plan for biodiversity conservation. This strategic plan has been used to coordinate and align targets to promote and enable more effective implementation across all biodiversity-related conventions. Results of a survey of 139 key stakeholders from 88 countries suggests streamlining across ministries and agencies, improved coordination mechanisms with all relevant stakeholders, and better knowledge sharing between conventions could improve cooperation among biodiversity-related conventions. The roadmap for improving synergies among conventions agreed to at the 13th Convention on Biological Diversity's Conference of Parties in 2016 includes actions such as mechanisms to avoid duplication in national reporting and monitoring on conventions and capacity building related to information and knowledge sharing. We suggest the scientific community can actively engage and contribute to the policy process by establishing a science-policy platform to address knowledge gaps; improving data gathering, reporting, and monitoring; developing indicators that adequately support implementation of national plans and strategies; and providing evidence-based recommendations to policy makers. The latter will be particularly important as 2020 approaches and work to develop a new biodiversity agenda for the next decade is beginning.


Mejora en la Colaboración en la Implementación de las Convenciones Mundiales sobre la Biodiversidad Resumen Ocho convenciones son las que forman la agrupación multilateral de acuerdos ambientales (MEAs, en inglés), los cuales proporcionan el marco de trabajo legal importante para la conservación y el uso sustentable de la naturaleza. Sin embargo, la preocupación por la tasa de implementación de estas convenciones a nivel nacional ha disparado discusiones sobre la efectividad de estas MEAs para detener la pérdida de la biodiversidad. Han surgido dos preocupaciones principales: la falta de capacidad y recursos y la falta de coherencia en la implementación de múltiples convenciones. Nos enfocamos en la segunda y consideramos los mecanismos mediante los cuales las convenciones internacionales se transforman en reglamentos y políticas nacionales. En específico, examinamos cómo el Plan Estratégico para la Biodiversidad 2011 - 2020 y los Objetivos de Biodiversidad de Aichi asociados han funcionado como un gran plan unificador para la conservación de la biodiversidad. Este plan estratégico se ha usado para coordinar y alinear los objetivos para promover y habilitar una implementación más efectiva a lo largo de todas las convenciones relacionadas con la biodiversidad. Los resultados de una encuesta entre 139 accionistas clave de 88 países sugieren la optimización en los ministerios y en las agencias, una coordinación mejorada de los mecanismos entre todos los accionistas relevantes, y una mejor partición del conocimiento entre las convenciones podría aumentar la cooperación entre las convenciones relacionadas con la biodiversidad. La hoja de ruta para mejorar las sinergias entre las convenciones, acordada en la Conferencia de Participantes de la 13ra Convención sobre la Diversidad Biológica en 2016, incluye acciones como los mecanismos para evitar la duplicación de reportes y monitoreos nacionales sobre las convenciones y la capacidad de construcción relacionada con la partición de la información y el conocimiento. Sugerimos que la comunidad científica pueda participar activamente y contribuir al proceso de políticas al establecer una plataforma política-científica que resuelva los vacíos en el conocimiento; mejore la recolección, reporte y monitoreo de datos, desarrolle indicadores que respalden adecuadamente a la implementación de planes y estrategias nacionales; y proporcione recomendaciones basadas en evidencia para los políticos. La última acción será de particular importancia conforme se aproxima el 2020 y se inicie la labor por desarrollar una nueva agenda de biodiversidad para la siguiente década.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales
12.
J Anal Methods Chem ; 2018: 2130390, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29854558

RESUMEN

A recently developed semiquantitative thin-layer chromatographic (SQ-TLC) assay has been employed in postmarketing surveillance of antimalarial medicines used in Malawi prior to HPLC assay. Both methods gave analogous results in a significant majority of the samples, with a good correlation (r = 0.9012) for the active pharmaceutical ingredients of the dosage forms assayed. Artemether-containing medicines had the highest percentage (92.67%) of samples with comparable results for both assays. The lowest percentage (66.67%) was observed in artesunate-containing medicines. The SQ-TLC method was validated for specificity, accuracy, precision, linearity, and stability according to the International Conference on Harmonisation guidelines, with the results falling within acceptable limits. For specificity, retention factor values of the test samples and reference standards were comparable, while accuracy and precision of 91.1 ± 5.7% were obtained for all samples. The method was linear in the range 1.0-2.0 µg/spot with a correlation coefficient of r = 0.9783. Stability tests also fell within acceptable limits. In this study, we present the validation of the SQ-TLC method and propose its adoption as a rapid screening tool for field estimation of the quality of antimalarial and other essential medicines in Malawi and other parts of the developing world prior to a more accurate HPLC assay.

13.
Molecules ; 21(10)2016 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-27754464

RESUMEN

Fungal pathogens continue to pose challenges to humans and plants despite efforts to control them. Two coumarins, robustic acid and thonningine-C isolated from Millettia thonningii, show promising activity against the fungus Candida albicans with minimum fungicidal concentration of 1.0 and 0.5 mg/mL, respectively. Molecular modelling against the putative bio-molecular target, lanosterol 14α-demethylase (CYP51), revealed a plausible binding mode for the active compounds, in which the hydroxyl group binds with a methionine backbone carboxylic group blocking access to the iron catalytic site. This binding disrupts the synthesis of several important sterols for the survival of fungi.


Asunto(s)
Antifúngicos/farmacología , Candida albicans/efectos de los fármacos , Cumarinas/farmacología , Millettia/química , Esterol 14-Desmetilasa/química , Antifúngicos/química , Dominio Catalítico/efectos de los fármacos , Cumarinas/química , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Isoflavonas/química , Isoflavonas/farmacología , Pruebas de Sensibilidad Microbiana , Modelos Moleculares , Simulación del Acoplamiento Molecular , Estructura Molecular , Unión Proteica , Esterol 14-Desmetilasa/metabolismo , Relación Estructura-Actividad
14.
IUCrJ ; 3(Pt 1): 51-60, 2016 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-26870381

RESUMEN

Through X-ray crystallographic fragment screening, 4-bromopyrazole was discovered to be a 'magic bullet' that is capable of binding at many of the ligand 'hot spots' found in HIV-1 reverse transcriptase (RT). The binding locations can be in pockets that are 'hidden' in the unliganded crystal form, allowing rapid identification of these sites for in silico screening. In addition to hot-spot identification, this ubiquitous yet specific binding provides an avenue for X-ray crystallographic phase determination, which can be a significant bottleneck in the determination of the structures of novel proteins. The anomalous signal from 4-bromopyrazole or 4-iodopyrazole was sufficient to determine the structures of three proteins (HIV-1 RT, influenza A endonuclease and proteinase K) by single-wavelength anomalous dispersion (SAD) from single crystals. Both compounds are inexpensive, readily available, safe and very soluble in DMSO or water, allowing efficient soaking into crystals.

16.
Malar J ; 14: 127, 2015 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-25890029

RESUMEN

BACKGROUND: The growing concern over the extent of anti-malarial medicine resistance in sub-Saharan Africa, driven largely by administration of sub-therapeutic doses derived from falsified and substandard medicines necessitates regular monitoring of the quality of these medicines to avert any potential public health disaster. This study aimed at determining the active pharmaceutical ingredient (API) content of anti-malarial medicines available in Malawi with respect to the manufacturers' label claim and pharmacopoeia specifications. METHODS: Samples of anti-malarial medicines (112) collected from both licensed and unlicensed markets throughout Malawi were subjected to visual inspection of dosage form and packaging, and registration verification with the regulatory body. Basic (colourimetric) tests were employed to establish the presence and identity of the requisite APIs. Semi-quantitative thin layer chromatography (SQ-TLC) was employed as a quick assay for the verification of identity and estimation of the API content while HPLC assays were used to quantify the APIs. The results were compared with pharmacopoeia specifications and manufacturers' label claims. For combination therapies, a sample was considered to have failed if one or more of its component APIs did not meet pharmacopoeia specifications. RESULTS: There was 86.6% registration status and 100% compliance with visual inspection and basic tests confirming the presence of requisite APIs. The identification test was confirmed by the SQ-TLC assay. API quantification by HPLC assay however, showed that 88.4% (99/112) of the samples failed the quality tests due to the presence of either insufficient or excessive API. CONCLUSIONS: The results suggest the existence of substandard anti-malarial medicines in Malawi. The presence of both excessive and insufficient artemisinin-based and non-artemisinin-based API, clearly points to poor adherence to GMP and improper handling during storage or distribution. The country relies heavily on imported anti-malarial medicines so there is an urgent need to carry out regular and thorough post-market surveillance of medicines to ensure better quality health care delivery.


Asunto(s)
Antimaláricos/análisis , Vigilancia de Productos Comercializados , Cromatografía Líquida de Alta Presión , Cromatografía en Capa Delgada , Colorimetría , Malaui
17.
Malar Res Treat ; 2014: 806416, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25400975

RESUMEN

This study, conducted as part of our overall goal of regular pharmacovigilance of antimalarial medicines, reports on the quality of 132 artemisinin-based antimalarial medicines distributed in Ghana and Togo. Three methods were employed in the quality evaluation-basic (colorimetric) tests for establishing the identity of the requisite active pharmaceutical ingredients (APIs), semi-quantitative TLC assay for the identification and estimation of API content, and HPLC assay for a more accurate quantification of API content. From the basic tests, only one sample totally lacked API. The HPLC assay, however, showed that 83.7% of the ACTs and 57.9% of the artemisinin-based monotherapies failed to comply with international pharmacopoeia requirements due to insufficient API content. In most of the ACTs, the artemisinin component was usually the insufficient API. Generally, there was a good correlation between the HPLC and SQ-TLC assays. The overall failure rates for both locally manufactured (77.3%) and imported medicines (77.5%) were comparable. Similarly the unregistered medicines recorded a slightly higher overall failure rate (84.7%) than registered medicines (70.8%). Only two instances of possible cross-border exchange of medicines were observed and there was little difference between the medicine quality of collections from border towns and those from inland parts of both countries.

18.
Acta Crystallogr Sect E Struct Rep Online ; 66(Pt 8): o2168, 2010 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-21588449

RESUMEN

In the asymmetric unit of the title compound, 2C(7)H(9)ClN(+)·C(9)H(6)O(4) (2-)·2H(2)O, there are two crystallographically independent cations, one dianion and two water mol-ecules. The dihedral angle between the two carboxyl-ate groups of the dianion is 78.1 (2)°. In the crystal, the components are held together by N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds, forming a layer parallel to the bc plane, with the hydro-philic and hydro-phobic groups located in the inner and outer regions of the layers, respectively.

19.
Acta Crystallogr Sect E Struct Rep Online ; 64(Pt 4): o713, 2008 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-21202104

RESUMEN

The title compound, C(20)H(16)O(5), {systematic name: 5-hydr-oxy-7-(4-hydroxy-phen-yl)-2,2-dimethyl-2H,6H-benzo[1,2-b:5,4-b']dipyran-6-one}, was obtained by demethyl-ation of the biologically active related compound, 4-O-methyl-alpinum-iso-flavone. The mol-ecular structure of the title compound is characterized by a fused tricyclic system that contains an approximately planar benzopyrone ring fragment. The six membered pyran ring adopts a half-chair conformation. Both ring systems show an out-of-plane twist. The dihedral angle between the mean plane of the benzopyrone system and the benzene ring is 54.29 (3)°. The mol-ecules are linked by O-H⋯O hydrogen bonds, forming a mol-ecular tape running along the b axis.

20.
Neurotoxicol Teratol ; 28(6): 673-80, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17046199

RESUMEN

Domoic acid (DA) is a marine biotoxin, produced by the diatom Pseudo-nitzchia spp., which has been shown to cause cognitive impairment in adults who are exposed via contaminated seafood. The neurobehavioral consequences of developmental exposure are much less well understood. In a previous study, we showed that a single prenatal exposure to DA in rats at mid-gestation caused neurobehavioral changes that persist into adulthood including increased susceptibility to the benchmark amnestic drug scopolamine. In the current study, we examined the lasting neurobehavioral consequences of DA exposure on the first day of postnatal life, a time in rats marking the completion of the major phase of neuroproliferation and corresponding to week 24 of human gestation. The effects of DA exposure at doses from 0.025-0.1 mg/kg (s.c.) twice per day on each of postnatal days 1 and 2 were compared with vehicle-treated controls and rats treated by the same protocol with 1 mg/kg of kainic acid. Following kainic acid exposure, a sex-selective effect was seen with females but not males showing a significant slowing of response latency in the radial-arm maze. The high DA dose of 0.1 mg/kg was quite toxic causing lethality in all of the offspring exposed and this group was excluded from further analysis. When the offspring in the 0.05 mg/kg DA dose group were tested, significant hypoactivity in the Figure-8 maze was observed during adolescence. No significant DA effects were seen in response latency or choice accuracy on the radial-arm maze during either acquisition or with challenge of the amnestic drug scopolamine. Early postnatal DA exposure in the rat can be lethal and sublethal exposure can cause neurobehavioral effects manifest in modest hypoactivity during the adolescent period. However, the sublethal persistent neurobehavioral toxicity appears to be less pervasive than reported effects following DA administered mid-gestation.


Asunto(s)
Conducta Animal/efectos de los fármacos , Ácido Kaínico/análogos & derivados , Fármacos Neuromusculares Despolarizantes/toxicidad , Animales , Proliferación Celular/efectos de los fármacos , Cerebelo/citología , Cerebelo/efectos de los fármacos , Interpretación Estadística de Datos , Giro Dentado/citología , Giro Dentado/efectos de los fármacos , Agonistas de Aminoácidos Excitadores/toxicidad , Femenino , Ácido Kaínico/toxicidad , Aprendizaje por Laberinto/efectos de los fármacos , Memoria/efectos de los fármacos , Actividad Motora/efectos de los fármacos , Antagonistas Muscarínicos/toxicidad , Neuronas/efectos de los fármacos , Estimulación Luminosa , Embarazo , Ratas , Ratas Sprague-Dawley , Escopolamina/toxicidad
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