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1.
J Patient Saf ; 20(7): e92-e96, 2024 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-39038074

RESUMEN

OBJECTIVES: The aims of the study were to describe inpatient harm events detected via an automatic electronic trigger system (ETS) and to consider their financial consequences. METHODS: Over a 27-month period, inpatient harm events were identified and documented in 1 healthcare system with 37 acute care facilities. Patients who experienced harm (all harm or preventable harm only) were compared with similar patients who did not. Clinical, financial, and demographic data were used to identify labor-adjusted direct variable costs (DVC) and potential differences in length of stay (LOS) associated with all-harm, preventable-harm, and nonharmed cohorts. Age-adjusted Charlson Comorbidity Index, case mix index, diagnosis-related groups, major diagnostic category, sex, age, location, diagnosis, adverse event category and subcategory, preventability, and harm severity were used to compare cohorts. Total harm events reported via the ETS and the health system's voluntary event reporting system were compared. RESULTS: Nearly 93,000 encounters for all-harm (n = 25,665) and nonharmed cohorts (n = 67,217) were compared by random sampling of diagnosis-related group-matched all-harm and nonharmed groups to ensure similar clinical conditions, as measured by Charlson Comorbidity Index and case mix index. Sampling (2 groups, n = 100 and n = 200) showed that increased LOS was associated with harm; yet other clinical comparators were similar across groups. the preventable-harm subcohort had longer LOS (10.7 versus 5.9 days) and higher DVC ($13,442 versus $8024) than the nonharmed cohort. Identification of harm events was nearly 6-fold higher with the ETS than with the voluntary event reporting system. CONCLUSIONS: Patients with preventable harm had increased LOS that was associated with higher DVC per preventable-harm encounter in a large US healthcare system.

2.
Organometallics ; 43(11): 1208-1212, 2024 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-38873573

RESUMEN

Ir-catalyzed C-H borylations of fluorinated and cyanated arenes with high meta-to-F/CN are described. Use of a dipyridyl hydrazone framework as the ancillary ligand and pinacolborane (HBpin) as the functionalizing reagent generates catalysts that are significantly more active and selective than 4,4'-di-tert-butyl-2,2'-bipyridine (dtbpy) for both electron-deficient and electron-rich substrates. Investigation of the ligand framework resulted in the observation of formal N-borylation of the hydrazone by HBpin, as evidenced by NMR spectroscopy and X-ray crystallography. Subsequent stoichiometric reactions of this adduct with an iridium precatalyst revealed the formation of an unusual IrI hydrazido. Isolation and use of this hydrazido reproduce the selectivity of in situ generated catalysts, suggesting that it leads to formation of the active species.

3.
Trials ; 23(1): 122, 2022 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-35130937

RESUMEN

BACKGROUND: Abused and neglected children are at increased risk of health problems throughout life, but negative effects may be ameliorated by nurturing family care. It is not known whether it is better to place these children permanently with substitute (foster or adoptive) families or to attempt to reform their birth families. Previously, we conducted a feasibility randomised controlled trial (RCT) of the New Orleans Intervention Model (NIM) for children aged 0-60 months coming into foster care in Glasgow. NIM is delivered by a multidisciplinary health and social care team and offers families, whose child has been taken into foster care, a structured assessment of family relationships followed by a trial of treatment aiming to improve family functioning. A recommendation is then made for the child to return home or for adoption. In the feasibility RCT, families were willing to be randomised to NIM or optimised social work services as usual and equipoise was maintained. Here we present the protocol of a substantive RCT of NIM including a new London site. METHODS: The study is a multi-site, pragmatic, single-blind, parallel group, cluster randomised controlled superiority trial with an allocation ratio of 1:1. We plan to recruit approximately 390 families across the sites, including those recruited in our feasibility RCT. They will be randomly allocated to NIM or optimised services as usual and followed up to 2.5 years post-randomisation. The principal outcome measure will be child mental health, and secondary outcomes will be child quality of life, the time taken for the child to be placed in permanent care (rehabilitation home or adoption) and the quality of the relationship with the primary caregiver. DISCUSSION: The study is novel in that infant mental health professionals rarely have a role in judicial decisions about children's care placements, and RCTs are rare in the judicial context. The trial will allow us to determine whether NIM is clinically and cost-effective in the UK and findings may have important implications for the use of mental health assessment and treatment as part of the decision-making about children in the care system.


Asunto(s)
Maltrato a los Niños , Cuidados en el Hogar de Adopción , Niño , Preescolar , Análisis Costo-Beneficio , Humanos , Lactante , Recién Nacido , Nueva Orleans , Calidad de Vida
4.
J Patient Saf ; 18(2): e407-e413, 2022 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-33797462

RESUMEN

OBJECTIVES: There is considerable evidence that providing patients with access to their health information is beneficial, but there is limited evidence regarding the effect of providing real-time patient safety-related information on health outcomes. The aim of this study was to evaluate the association between use of an electronic patient safety dashboard (Safety Advisor) and health outcomes. METHODS: The Safety Advisor was implemented in 6 adult medicine units at one hospital in the United States. Study participants were asked to use the Safety Advisor, which provides real-time patient safety-related information through a Web-based portal. The primary outcome was the association between the application usage and health outcomes (readmission rate and mortality rate) per 3 different usage groups, and the secondary outcome was the association of Patient Activation Measure (PAM) scores with use. RESULTS: One hundred eighty-one participants were included for the data analysis. Approximately 90% of users accessed the application during the first 4 days of enrollment: 51.6% of users only accessed it on 1 day, whereas 5.8% used it more than 3 days. Patients who used the application more had lower 30-day readmission rates (P = 0.01) compared with the lower-usage group. The PAM scores for users of Safety Advisor (71.8) were higher than the nonpatient portal users (60.8, P < 0.0001). CONCLUSIONS: We found an association between the use of Safety Advisor and health outcomes. Differences in PAM scores between groups were statistically significant. A larger-scale randomized control trial is warranted to evaluate the impact on patient outcomes among a high-risk patient population.


Asunto(s)
Hospitales , Readmisión del Paciente , Adulto , Electrónica , Humanos , Reproducibilidad de los Resultados , Estados Unidos
5.
Molecules ; 25(7)2020 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-32290238

RESUMEN

Borylated aryl alkynes have been synthesized via one-pot iridium catalyzed C-H borylation (CHB)/Sonogashira cross-coupling of aryl bromides. Direct borylation of aryl alkynes encountered problems related to the reactivity of the alkyne under CHB conditions. However, tolerance of aryl bromides to CHB made possible a subsequent Sonogashira cross-coupling to access the desired borylated aryl alkynes.


Asunto(s)
Alquinos/química , Carbono/química , Hidrógeno/química , Iridio/química , Catálisis , Técnicas de Química Sintética , Acoplamiento Oxidativo
6.
J Am Chem Soc ; 141(39): 15483-15487, 2019 10 02.
Artículo en Inglés | MEDLINE | ID: mdl-31525037

RESUMEN

Para C-H borylations (CHB) of tetraalkylammonium sulfates and sulfamates have been achieved using bipyridine-ligated Ir boryl catalysts. Selectivities can be modulated by both the length of the alkyl groups in the tetraalkylammonium cations and the substituents on the bipyridine ligands. Ion pairing, where the alkyl groups of the cation shield the meta C-H bonds in the counteranions, is proposed to account for para selectivity. The 4,4'-dimethoxy-2,2'-bipyridine ligand gave superior selectivities.


Asunto(s)
Compuestos de Anilina/química , Alcohol Bencilo/química , Iridio/química , Fenoles/química , Catálisis , Modelos Moleculares , Estructura Molecular , Electricidad Estática
7.
Org Lett ; 21(16): 6388-6392, 2019 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-31393137

RESUMEN

By modifying ligand steric and electronic profiles it is possible to C-H borylate ortho or meta to substituents in aromatic and heteroaromatic compounds, where steric differences between accessible C-H sites are small. Dramatic effects on selectivities between reactions using B2pin2 or 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (HBpin) are described for the first time. Judicious ligand and borane combinations give highly regioselective C-H borylations on substrates where typical borylation protocols afford poor selectivities.

8.
Proc Natl Acad Sci U S A ; 116(8): 2849-2853, 2019 02 19.
Artículo en Inglés | MEDLINE | ID: mdl-30655346

RESUMEN

We report that ruthenium polypyridyl complexes can catalyze ammonia oxidation to dinitrogen at room temperature and ambient pressure. During bulk electrolysis experiments, gas chromatography and mass spectrometry analysis of the headspace in the electrochemical cell showed that dinitrogen and dihydrogen are generated from ammonia with high faradaic efficiencies. A proposed mechanism where a hydrazine complex is the initial N-N bonded intermediate is supported by chemical and electrochemical experiments. This is a well-defined system for homogeneous electrocatalytic ammonia oxidation. It establishes a platform for answering mechanistic questions relevant to using ammonia to store and distribute renewable energy.


Asunto(s)
Amoníaco/química , Complejos de Coordinación/química , Energía Renovable , Rutenio/química , Catálisis , Electrólisis , Cromatografía de Gases y Espectrometría de Masas , Nitrógeno/química , Oxidación-Reducción
9.
Jt Comm J Qual Patient Saf ; 43(4): 155-165, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-28325203

RESUMEN

BACKGROUND: From 2009 through 2012, the Adventist Health System Patient Safety Organization (AHS PSO) used the Global Trigger Tool method for harm identification and demonstrated harm reduction. Although the awareness of harm demonstrated opportunities for improvement across the system, leaders determined that the human and fiscal resources required to continue with a retrospective manual harm identification process were unsustainable. In addition, there was growing concern that the identification of harm after the patient's discharge did not allow for intervention during the hospital stay. Therefore, the AHS PSO decided to seek an alternative method for patient harm identification. METHODS: The AHS PSO and another PSO jointly developed a novel automated all-cause harm trigger identification system that allowed for real-time bedside intervention, real-time trend analysis affecting patient safety, and continued learning about harm measurement. A sociotechnical approach of people, process, and technology was used at two pilot hospitals sharing the same electronic health record platform. Automated positive harm triggers and work-flow models were developed and evaluated. RESULTS: Combined data from the two hospitals in a period of 11 consecutive months indicated (1) a total of 2,696 harms (combined hospital-acquired and outside-acquired); (2) that hypoglycemia (blood glucose ≤ 40 mg/dL) was the most frequently identified harm; (3) 256 harms related to the Patient Safety Indicator 90 (PSI 90) Composite descriptions versus 77 harms reported to regulatory harm reduction programs; and (4) that almost one third (32%) of total harms were classified as outside-acquired. CONCLUSION: The automated harm trigger system revealed not only more harm but a broader scope of harm and led to a deeper understanding of patient safety vulnerabilities.


Asunto(s)
Alarmas Clínicas , Enfermedad Iatrogénica , Errores Médicos/estadística & datos numéricos , Seguridad del Paciente , Algoritmos , Hospitales , Humanos , Sistemas de Registros Médicos Computarizados , Proyectos Piloto
10.
PLoS One ; 11(6): e0155932, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27249673

RESUMEN

In the Arctic Ocean's southern Beaufort Sea (SB), the length of the sea ice melt season (i.e., period between the onset of sea ice break-up in summer and freeze-up in fall) has increased substantially since the late 1990s. Historically, polar bears (Ursus maritimus) of the SB have mostly remained on the sea ice year-round (except for those that came ashore to den), but recent changes in the extent and phenology of sea ice habitat have coincided with evidence that use of terrestrial habitat is increasing. We characterized the spatial behavior of polar bears spending summer and fall on land along Alaska's north coast to better understand the nexus between rapid environmental change and increased use of terrestrial habitat. We found that the percentage of radiocollared adult females from the SB subpopulation coming ashore has tripled over 15 years. Moreover, we detected trends of earlier arrival on shore, increased length of stay, and later departure back to sea ice, all of which were related to declines in the availability of sea ice habitat over the continental shelf and changes to sea ice phenology. Since the late 1990s, the mean duration of the open-water season in the SB increased by 36 days, and the mean length of stay on shore increased by 31 days. While on shore, the distribution of polar bears was influenced by the availability of scavenge subsidies in the form of subsistence-harvested bowhead whale (Balaena mysticetus) remains aggregated at sites along the coast. The declining spatio-temporal availability of sea ice habitat and increased availability of human-provisioned resources are likely to result in increased use of land. Increased residency on land is cause for concern given that, while there, bears may be exposed to a greater array of risk factors including those associated with increased human activities.


Asunto(s)
Biología Marina , Conducta Predatoria , Ursidae/fisiología , Animales , Regiones Árticas , Cambio Climático , Cubierta de Hielo
11.
J Org Chem ; 80(16): 8341-53, 2015 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-26226056

RESUMEN

Ir-catalyzed deborylation can be used to selectively deuterate aromatic and heteroaromatic substrates. Combined with the selectivities of Ir-catalyzed C-H borylations, uniquely labeled compounds can be prepared. In addition, diborylation/deborylation reactions provide monoborylated regioisomers that complement those prepared by C-H borylation. Comparisons between Ir-catalyzed deborylations and Pd-catalyzed deborylations of diborylated indoles described by Movassaghi are made. The Ir-catalyzed process is more effective for deborylating aromatics and is generally more effective in the monodeborylation of diborylated thiophenes. These processes can be applied to complex molecules such as clopidogrel.


Asunto(s)
Compuestos de Boro/química , Ácidos Borónicos/síntesis química , Deuterio/química , Indoles/química , Ácidos Borónicos/química , Catálisis , Ésteres , Estructura Molecular
12.
Biochem Pharmacol ; 79(9): 1272-80, 2010 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-20067776

RESUMEN

Nuclear factor-kappa B (NF-kappaB) is a transcription factor that plays a critical role across many cellular processes including embryonic and neuronal development, cell proliferation, apoptosis, and immune responses to infection and inflammation. Dysregulation of NF-kappaB signaling is associated with inflammatory diseases and certain cancers. Constitutive activation of NF-kappaB signaling has been found in some types of tumors including breast, colon, prostate, skin and lymphoid, hence therapeutic blockade of NF-kappaB signaling in cancer cells provides an attractive strategy for the development of anticancer drugs. To identify small molecule inhibitors of NF-kappaB signaling, we screened approximately 2800 clinically approved drugs and bioactive compounds from the NIH Chemical Genomics Center Pharmaceutical Collection (NPC) in a NF-kappaB mediated beta-lactamase reporter gene assay. Each compound was tested at fifteen different concentrations in a quantitative high throughput screening format. We identified nineteen drugs that inhibited NF-kappaB signaling, with potencies as low as 20 nM. Many of these drugs, including emetine, fluorosalan, sunitinib malate, bithionol, narasin, tribromsalan, and lestaurtinib, inhibited NF-kappaB signaling via inhibition of IkappaBalpha phosphorylation. Others, such as ectinascidin 743, chromomycin A3 and bortezomib utilized other mechanisms. Furthermore, many of these drugs induced caspase 3/7 activity and had an inhibitory effect on cervical cancer cell growth. Our results indicate that many currently approved pharmaceuticals have previously unappreciated effects on NF-kappaB signaling, which may contribute to anticancer therapeutic effects. Comprehensive profiling of approved drugs provides insight into their molecular mechanisms, thus providing a basis for drug repurposing.


Asunto(s)
Antineoplásicos/farmacología , Ensayos de Selección de Medicamentos Antitumorales , FN-kappa B/antagonistas & inhibidores , Línea Celular , Relación Dosis-Respuesta a Droga , Genes Reporteros , Ensayos Analíticos de Alto Rendimiento , Humanos , Quinasa I-kappa B/metabolismo , L-Lactato Deshidrogenasa/metabolismo , Estructura Molecular , FN-kappa B/fisiología , Transducción de Señal
13.
Mol Cancer ; 8: 117, 2009 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-20003191

RESUMEN

BACKGROUND: Hypoxia-inducible factor-1 (HIF-1) is the major hypoxia-regulated transcription factor that regulates cellular responses to low oxygen environments. HIF-1 is composed of two subunits: hypoxia-inducible HIF-1alpha and constitutively-expressed HIF-1beta. During hypoxic conditions, HIF-1alpha heterodimerizes with HIF-1beta and translocates to the nucleus where the HIF-1 complex binds to the hypoxia-response element (HRE) and activates expression of target genes implicated in cell growth and survival. HIF-1alpha protein expression is elevated in many solid tumors, including those of the cervix and brain, where cells that are the greatest distance from blood vessels, and therefore the most hypoxic, express the highest levels of HIF-1alpha. Therapeutic blockade of the HIF-1 signaling pathway in cancer cells therefore provides an attractive strategy for development of anticancer drugs. To identify small molecule inhibitors of the HIF-1 pathway, we have developed a cell-based reporter gene assay and screened a large compound library by using a quantitative high-throughput screening (qHTS) approach. RESULTS: The assay is based upon a beta-lactamase reporter under the control of a HRE. We have screened approximate 73,000 compounds by qHTS, with each compound tested over a range of seven to fifteen concentrations. After qHTS we have rapidly identified three novel structural series of HIF-1 pathway Inhibitors. Selected compounds in these series were also confirmed as inhibitors in a HRE beta-lactamase reporter gene assay induced by low oxygen and in a VEGF secretion assay. Three of the four selected compounds tested showed significant inhibition of hypoxia-induced HIF-1alpha accumulation by western blot analysis. CONCLUSION: The use of beta-lactamase reporter gene assays, in combination with qHTS, enabled the rapid identification and prioritization of inhibitors specific to the hypoxia induced signaling pathway.


Asunto(s)
Factor 1 Inducible por Hipoxia/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos , Línea Celular Tumoral , Genes Reporteros , Humanos , Factor 1 Inducible por Hipoxia/metabolismo , Oxígeno/metabolismo , Interferencia de ARN , beta-Lactamasas/genética
14.
Infect Immun ; 76(9): 4332-44, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18591232

RESUMEN

The serine repeat antigen (SERA) proteins of the malaria parasites Plasmodium spp. contain a putative enzyme domain similar to that of papain family cysteine proteases. In Plasmodium falciparum parasites, more than half of the SERA family proteins, including the most abundantly expressed form, SERA5, have a cysteine-to-serine substitution within the putative catalytic triad of the active site. Although SERA5 is required for blood-stage parasite survival, the occurrence of a noncanonical catalytic triad casts doubt on the importance of the enzyme domain in this function. We used phage display to identify a small (14-residue) disulfide-bonded cyclic peptide (SBP1) that targets the enzyme domain of SERA5. Biochemical characterization of the interaction shows that it is dependent on the conformation of both the peptide and protein. Addition of this peptide to parasite cultures compromised development of late-stage parasites compared to that of control parasites or those incubated with equivalent amounts of the carboxymethylated peptide. This effect was similar in two different strains of P. falciparum as well as in a transgenic strain where the gene encoding the related serine-type parasitophorous vacuole protein SERA4 was deleted. In compromised parasites, the SBP1 peptide crosses both the erythrocyte and parasitophorous vacuole membranes and accumulates within the parasitophorous vacuole. In addition, both SBP1 and SERA5 were identified in the parasite cytosol, indicating that the plasma membrane of the parasite was compromised as a result of SBP1 treatment. These data implicate an important role for SERA5 in the regulation of the intraerythrocytic development of late-stage parasites and as a target for drug development.


Asunto(s)
Antígenos de Protozoos/metabolismo , Antimaláricos/farmacología , Cisteína Endopeptidasas/metabolismo , Péptidos Cíclicos/farmacología , Plasmodium falciparum/efectos de los fármacos , Animales , Citosol/química , Biblioteca de Péptidos , Plasmodium falciparum/crecimiento & desarrollo , Unión Proteica , Vacuolas/química , Vacuolas/parasitología
15.
Infect Immun ; 75(12): 5565-74, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-17893128

RESUMEN

Serine repeat antigens (SERAs) are a family of secreted "cysteine-like" proteases of Plasmodium parasites. Several SERAs possess an atypical active-site serine residue in place of the canonical cysteine. The human malaria parasite Plasmodium falciparum possesses six "serine-type" (SERA1 to SERA5 and SERA9) and three "cysteine-type" (SERA6 to SERA8) SERAs. Here, we investigate the importance of the serine-type SERAs to blood-stage parasite development and examine the extent of functional redundancy among this group. We attempted to knock out the four P. falciparum serine-type SERA genes that have not been disrupted previously. SERA1, SERA4, and SERA9 knockout lines were generated, while only SERA5, the most strongly expressed member of the SERA family, remained refractory to genetic deletion. Interestingly, we discovered that while SERA4-null parasites completed the blood-stage cycle normally, they exhibited a twofold increase in the level of SERA5 mRNA. The inability to disrupt SERA5 and the apparent compensatory increase in SERA5 expression in response to the deletion of SERA4 provides evidence for an important blood-stage function for the serine-type SERAs and supports the notion of functional redundancy among this group. Such redundancy is consistent with our phylogenetic analysis, which reveals a monophyletic grouping of the serine-type SERAs across the genus Plasmodium and a predominance of postspeciation expansion. While SERA5 is to some extent further validated as a target for vaccine and drug development, our data suggest that the expression level of other serine-type SERAs is the only barrier to escape from anti-SERA5-specific interventions.


Asunto(s)
Antígenos de Protozoos/inmunología , Vacunas contra la Malaria/inmunología , Plasmodium falciparum/inmunología , Serina Endopeptidasas/inmunología , Animales , Antígenos de Protozoos/genética , Antimaláricos/química , Antimaláricos/farmacología , Apicomplexa/genética , Intercambio Genético , ADN Recombinante/genética , Diseño de Fármacos , Eritrocitos/parasitología , Eliminación de Gen , Humanos , Vacunas contra la Malaria/genética , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/prevención & control , Filogenia , Plasmodium falciparum/enzimología , Plasmodium falciparum/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Serina Endopeptidasas/metabolismo , Inhibidores de Serina Proteinasa/metabolismo , Transfección , Regulación hacia Arriba
16.
EMBO J ; 24(13): 2306-17, 2005 Jul 06.
Artículo en Inglés | MEDLINE | ID: mdl-15961998

RESUMEN

The human malarial parasite Plasmodium falciparum exports proteins to destinations within its host erythrocyte, including cytosol, surface and membranous profiles of parasite origin termed Maurer's clefts. Although several of these exported proteins are determinants of pathology and virulence, the mechanisms and trafficking signals underpinning protein export are largely uncharacterized-particularly for exported transmembrane proteins. Here, we have investigated the signals mediating trafficking of STEVOR, a family of transmembrane proteins located at the Maurer's clefts and believed to play a role in antigenic variation. Our data show that, apart from a signal sequence, a minimum of two addition signals are required. This includes a host cell targeting signal for export to the host erythrocyte and a transmembrane domain for final sorting to Maurer's clefts. Biochemical studies indicate that STEVOR traverses the secretory pathway as an integral membrane protein. Our data suggest general principles for transport of transmembrane proteins to the Maurer's clefts and provide new insights into protein sorting and trafficking processes in P. falciparum.


Asunto(s)
Antígenos de Protozoos/metabolismo , Eritrocitos/metabolismo , Proteínas de la Membrana/metabolismo , Plasmodium falciparum/metabolismo , Secuencia de Aminoácidos , Animales , Antígenos de Protozoos/genética , Membrana Eritrocítica/metabolismo , Membrana Eritrocítica/parasitología , Eritrocitos/parasitología , Proteínas Fluorescentes Verdes/genética , Interacciones Huésped-Parásitos , Humanos , Proteínas de la Membrana/genética , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Señales de Clasificación de Proteína , Transporte de Proteínas , Proteínas Recombinantes de Fusión/metabolismo
17.
J Biol Chem ; 278(48): 48169-77, 2003 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-13679369

RESUMEN

Serine repeat antigen 5 (SERA5) is an abundant antigen of the human malaria parasite Plasmodium falciparum and is the most strongly expressed member of the nine-gene SERA family. It appears to be essential for the maintenance of the erythrocytic cycle, unlike a number of other members of this family, and has been implicated in parasite egress and/or erythrocyte invasion. All SERA proteins possess a central domain that has homology to papain except in the case of SERA5 (and some other SERAs), where the active site cysteine has been replaced with a serine. To investigate if this domain retains catalytic activity, we expressed, purified, and refolded a recombinant form of the SERA5 enzyme domain. This protein possessed chymotrypsin-like proteolytic activity as it processed substrates downstream of aromatic residues, and its activity was reversed by the serine protease inhibitor 3,4-diisocoumarin. Although all Plasmodium SERA enzyme domain sequences share considerable homology, phylogenetic studies revealed two distinct clusters across the genus, separated according to whether they possess an active site serine or cysteine. All Plasmodia appear to have at least one member of each group. Consistent with separate biological roles for members of these two clusters, molecular modeling studies revealed that SERA5 and SERA6 enzyme domains have dramatically different surface properties, although both have a characteristic papain-like fold, catalytic cleft, and an appropriately positioned catalytic triad. This study provides impetus for the examination of SERA5 as a target for antimalarial drug design.


Asunto(s)
Antígenos de Protozoos/química , Antígenos de Protozoos/fisiología , Papaína/química , Plasmodium falciparum/metabolismo , Secuencia de Aminoácidos , Animales , Antimaláricos/farmacología , Sitios de Unión , Dominio Catalítico , Cromatografía Líquida de Alta Presión , Cumarinas/farmacología , Cisteína/química , Disulfuros , Electroforesis en Gel de Poliacrilamida , Immunoblotting , Espectrometría de Masas , Modelos Moleculares , Datos de Secuencia Molecular , Filogenia , Conformación Proteica , Pliegue de Proteína , Estructura Terciaria de Proteína , Inhibidores de Serina Proteinasa/farmacología , Factores de Tiempo
18.
J Biol Chem ; 277(49): 47524-32, 2002 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-12228245

RESUMEN

The Plasmodium falciparum serine repeat antigen (SERA) has shown considerable promise as a blood stage vaccine for the control of malaria. A related protein, SERPH, has also been described in P. falciparum. Whereas their biological role remains unknown, both proteins possess papain-like protease domains that may provide attractive targets for therapeutic intervention. Genomic sequencing has recently shown that SERA and SERPH are the fifth and sixth genes, respectively, in a cluster of eight SERA homologues present on chromosome 2. In this paper, the expression and functional relevance of these eight genes and of a ninth SERA homologue found on chromosome 9 were examined in blood stage parasites. Using reverse transcriptase-PCR and microarray approaches, we demonstrate that whereas mRNA to all nine SERA genes is synthesized late in the erythrocytic cycle, it is those genes in the central region of the chromosome 2 cluster that are substantially up-regulated at this time. Using antibodies specific to each SERA, it was apparent that SERA4 to -6, and possibly also SERA9, are synthesized in blood stage parasites. The reactivity of antibodies from malaria-immune individuals with the SERA recombinant proteins suggested that SERA2 and SERA3 are also expressed at least in some parasite populations. To examine whether SERA genes are essential to blood stage growth, each of the eight chromosome 2 SERA genes was targeted for disruption. Whereas genes at the periphery of the cluster were mostly dispensable (SERA2 and -3 and SERA7 and -8), those in the central region (SERA4 to -6) could not be disrupted. The inability to disrupt SERA4, -5, and -6 is consistent with their apparent dominant expression and implies an important role for these genes in maintenance of the erythrocytic cycle.


Asunto(s)
Antígenos de Protozoos/biosíntesis , Antígenos de Protozoos/genética , Eritrocitos/parasitología , Plasmodium falciparum/genética , Plasmodium falciparum/metabolismo , Animales , Southern Blotting , Western Blotting , Cromosomas , ADN/metabolismo , Electroforesis en Gel de Poliacrilamida , Eritrocitos/metabolismo , Femenino , Técnica del Anticuerpo Fluorescente Indirecta , Glutatión Transferasa/metabolismo , Ratones , Ratones Endogámicos BALB C , Microscopía Fluorescente , Modelos Genéticos , Familia de Multigenes , Análisis de Secuencia por Matrices de Oligonucleótidos , Estructura Terciaria de Proteína , Conejos , Proteínas Recombinantes/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Tiempo , Transfección
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