Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 339
Filtrar
1.
Acad Med ; 90(2): 185-90, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25354070

RESUMEN

PROBLEM: Many health care organizations seek physicians to lead quality improvement (QI) efforts, yet struggle to find individuals with the necessary expertise. Although most residency programs incorporate QI and patient safety principles into their curricula, few provide a specialized training program for residents exploring careers as physician leaders in quality. APPROACH: Recognizing this training void, the authors designed and implemented the Healthcare Leadership in Quality (HLQ) track for residents at the University of Pennsylvania Health System in 2010. This longitudinal, two-year graduate medical education (GME) track aligns with the quality goals of the University of Pennsylvania Health System and includes a core curriculum, integration into an interprofessional health care leadership team that is accountable for quality and safety outcomes on a hospital unit, a capstone QI project, and mentorship. OUTCOMES: Early evaluation has demonstrated the feasibility and efficacy of the track diverse graduate medical education training programs. Using Yardley and Dornan's interpretation of the Kirkpatrick framework, the authors have demonstrated the track's impact on four levels of educational and organizational outcomes. NEXT STEPS: Building on their early experiences, the authors are integrating project and time management skills into the core curriculum, and they are focusing more effort on faculty development in QI mentorship. Additionally, the authors plan to follow HLQ track graduates to determine whether they seek leadership roles in quality and safety and to assess the influence of the program on their careers.


Asunto(s)
Educación de Postgrado en Medicina/organización & administración , Internado y Residencia/organización & administración , Desarrollo de Programa , Mejoramiento de la Calidad , Curriculum , Humanos , Liderazgo , Mentores , Pennsylvania , Rol del Médico
2.
Jt Comm J Qual Patient Saf ; 39(9): 387-95, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24147350

RESUMEN

BACKGROUND: Despite the importance of reducing inpatient mortality, little has been reported about establishing a hospitalwide, systematic process to review and address inpatient deaths. In 2006 the University of Pennsylvania Health System's Mortality Review Committee was established and charged with reducing inpatient mortality as measured by the mortality index--observed/expected mortality. METHODS: Between 2006 and 2012, through interdisciplinary meetings and analysis of administrative data and chart reviews, the Mortality Review Committee identified a number of opportunities for improvement in the quality of patient care. Several programmatic interventions, such as those aimed at improving sepsis and delirium recognition and management, were initiated through the committee. RESULTS: During the committee's first six years of activity, the University HealthSystem Consortium (UHC) mortality index decreased from 1.08 to 0.53, with observed mortality decreasing from 2.45% to 1.62%. Interventions aimed at improving sepsis management implemented between 2007 and 2008 were associated with increases in severe sepsis survival from 40% to 56% and septic shock survival from 42% to 54%. The mortality index for sepsis decreased from 2.45 to 0.88. Efforts aimed at improving delirium management implemented between 2008 and 2009 were associated with an increase in the proportion of patients receiving a "timely" intervention from 18% to 57% and with a twofold increase in the percentage of patients discharged to home. DISCUSSION: The establishment of a mortality review committee was associated with a significant reduction in the mortality index. Keys to success include interdisciplinary membership, partnerships with local providers, and a multipronged approach to identifying important clinical opportunities and to implementing effective interventions.


Asunto(s)
Comités Consultivos/organización & administración , Mortalidad Hospitalaria/tendencias , Hospitales de Enseñanza/organización & administración , Mejoramiento de la Calidad/organización & administración , Accidentes por Caídas/mortalidad , Cuidadores , Comunicación , Delirio/mortalidad , Cuidados Paliativos al Final de la Vida , Humanos , Sistemas de Información/organización & administración , Satisfacción del Paciente , Pennsylvania , Indicadores de Calidad de la Atención de Salud , Sepsis/mortalidad
6.
Am J Infect Control ; 34(3): 142-9, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16630978

RESUMEN

BACKGROUND: The Centers for Disease Control and Prevention (CDC) systematically reviewed published studies for the Healthcare Infection Control Practices Advisory Committee (HICPAC) in preparation for guidance to states on mandatory public reporting systems for health care-associated infections (HAI) in hospitals. The HICPAC asked whether public reporting systems are effective in improving health care performance, by measured improvements in clinical processes or patients' health status as the intended outcomes, including but not limited to reduced HAI events; and whether new evidence of effectiveness of private reporting policies to reduce HAI had been published since the 1970s landmark Study on the Efficacy of Nosocomial Infection Control study. METHODS: Public reporting systems are information provided to the public about the quality of health services. Of 450 published papers reviewed using specific inclusion and exclusion criteria, 10 studies qualified for detailed, protocol-based abstractions. RESULTS: Findings indicate that the evidence for effectiveness for public reporting systems to improve health care performance is inconclusive. No studies have investigated reduction of HAI as an outcome of public reporting. CONCLUSION: Rigorous evaluation of mandatory public reporting systems for HAI is recommended to ensure that stakeholders' needs are identified and met.


Asunto(s)
Infección Hospitalaria/epidemiología , Recolección de Datos/métodos , Notificación Obligatoria , Calidad de la Atención de Salud/normas , Infección Hospitalaria/prevención & control , Infección Hospitalaria/terapia , Humanos , Calidad de la Atención de Salud/organización & administración , Estados Unidos
8.
Tuberculosis (Edinb) ; 83(1-3): 91-7, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12758196

RESUMEN

Much of the early structural definition of the cell wall of Mycobacterium spp. was initiated in the 1960s and 1970s. There was a long period of inactivity, but more recent developments in NMR and mass spectral analysis and definition of the M. tuberculosis genome have resulted in a thorough understanding, not only of the structure of the mycobacterial cell wall and its lipids but also the basic genetics and biosynthesis. Our understanding nowadays of cell-wall architecture amounts to a massive "core" comprised of peptidoglycan covalently attached via a linker unit (L-Rha-D-GlcNAc-P) to a linear galactofuran, in turn attached to several strands of a highly branched arabinofuran, in turn attached to mycolic acids. The mycolic acids are oriented perpendicular to the plane of the membrane and provide a truly special lipid barrier responsible for many of the physiological and disease-inducing aspects of M. tuberculosis. Intercalated within this lipid environment are the lipids that have intrigued researchers for over five decades: the phthiocerol dimycocerosate, cord factor/dimycolyltrehalose, the sulfolipids, the phosphatidylinositol mannosides, etc. Knowledge of their roles in "signaling" events, in pathogenesis, and in the immune response is now emerging, sometimes piecemeal and sometimes in an organized fashion. Some of the more intriguing observations are those demonstrating that mycolic acids are recognized by CD1-restricted T-cells, that antigen 85, one of the most powerful protective antigens of M. tuberculosis, is a mycolyltransferase, and that lipoarabinomannan (LAM), when "capped" with short mannose oligosaccharides, is involved in phagocytosis of M. tuberculosis. Definition of the genome of M. tuberculosis has greatly aided efforts to define the biosynthetic pathways for all of these exotic molecules: the mycolic acids, the mycocerosates, phthiocerol, LAM, and the polyprenyl phosphates. For example, we know that synthesis of the entire core is initiated on a decaprenyl-P with synthesis of the linker unit, and then there is concomitant extension of the galactan and arabinan chains while this intermediate is transported through the cytoplasmic membrane. The final steps in these events, the attachment of mycolic acids and ligation to peptidoglycan, await definition and will prove to be excellent targets for a new generation of anti-tuberculosis drugs.


Asunto(s)
Mycobacterium tuberculosis/ultraestructura , Pared Celular/fisiología , Pared Celular/ultraestructura , Galactanos/biosíntesis , Lípidos de la Membrana/fisiología , Mycobacterium tuberculosis/metabolismo , Peptidoglicano/biosíntesis
9.
Br J Gen Pract ; 52(476): 208-9, 2002 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-12030663

RESUMEN

The impact of randomised controlled trials on subsequent practice has only occasionally been assessed. Doing so is particularly necessary when unusual and possibly controversial treatments are being used. The aim of this study was to assess the practical implications of the results of the placebo-controlled primary prevention thrombosis prevention trial, in which the active treatment regimens were combined warfarin and aspirin, warfarin alone, and aspirin alone. Both active agents were given in low doses. Decisions on post-trial management were sought about men who continued with randomly-allocated treatment until the trial ended. The results of the trial appeared to have influenced decisions about future management. While aspirin was clearly the most frequent choice, a regimen involving warfarin was also used for a substantial proportion of men. Prior experience of acceptability, effectiveness, and safety probably played a significant part in decisions to continue with or switch to a warfarin-containing regimen. The findings may provide a measure of reassurance about the value of oral anticoagulation in other settings, particularly atrial fibrillation where, despite the results of trials showing major reductions in stroke, anticoagulation is underused.


Asunto(s)
Anticoagulantes/uso terapéutico , Aspirina/uso terapéutico , Inhibidores de Agregación Plaquetaria/uso terapéutico , Trombosis/prevención & control , Warfarina/uso terapéutico , Método Doble Ciego , Medicina Familiar y Comunitaria , Femenino , Estudios de Seguimiento , Humanos , Masculino
10.
Tuberculosis (Edinb) ; 82(6): 293-300, 2002.
Artículo en Inglés | MEDLINE | ID: mdl-12623272

RESUMEN

SETTING: Members of the Mycobacterium avium complex (MAC) are responsible for mycobacterial disease in children, the aged and in immunocompromised individuals. The complex consists of different species, serovars and morphologic forms that vary in virulence. One isolate of the MAC is currently being sequenced (MAC 104) and was chosen based on its derivation from an AIDS patient and the fact that it could be genetically manipulated. OBJECTIVE: MAC 104 was therefore analyzed for virulence, colony morphotype and expression of the glycopeptidolipid (GPL) responsible for serotying differences and the rough to smooth morphological switch. RESULTS: The isolate was found to be virulent in the murine model of low-dose aerosol infection in that it could colonize the lung, proliferate within the tissue and disseminate to other organs. MAC 104 expressed a variety of colony morphotypes, the most prevalent of which were smooth opaque, smooth transparent and rough. All three morphotypes could persist in the lung; however, the transparent and rough morphotypes grew more rapidlyinvivo. The rough morphotype was unusual in that it expressed an atypical form of the GPL usually absent from rough morphotypes. CONCLUSION: This characterization complements the genome data and confirms that MAC 104 behaves similarly to other MAC isolates.


Asunto(s)
Antígenos Bacterianos/análisis , Antígenos de Superficie/análisis , Mycobacterium avium/patogenicidad , Animales , Técnicas de Tipificación Bacteriana , Cromatografía de Gases , Enfermedades Pulmonares/microbiología , Espectrometría de Masas , Ratones , Ratones Endogámicos C57BL , Infección por Mycobacterium avium-intracellulare/microbiología , Fenotipo
11.
J Biol Chem ; 276(50): 47029-37, 2001 Dec 14.
Artículo en Inglés | MEDLINE | ID: mdl-11600501

RESUMEN

Mycolic acids are vital components of the Mycobacterium tuberculosis cell wall, and enzymes involved in their formation represent attractive targets for the discovery of novel anti-tuberculosis agents. Biosynthesis of the fatty acyl chains of mycolic acids involves two fatty acid synthetic systems, the multifunctional polypeptide fatty acid synthase I (FASI), which performs de novo fatty acid synthesis, and the dissociated FASII system, which consists of monofunctional enzymes, and acyl carrier protein (ACP) and elongates FASI products to long chain mycolic acid precursors. In this study, we present the initial characterization of purified KasA and KasB, two beta-ketoacyl-ACP synthase (KAS) enzymes of the M. tuberculosis FASII system. KasA and KasB were expressed in E. coli and purified by affinity chromatography. Both enzymes showed activity typical of bacterial KASs, condensing an acyl-ACP with malonyl-ACP. Consistent with the proposed role of FASII in mycolic acid synthesis, analysis of various acyl-ACP substrates indicated KasA and KasB had higher specificity for long chain acyl-ACPs containing at least 16 carbons. Activity of KasA and KasB increased with use of M. tuberculosis AcpM, suggesting that structural differences between AcpM and E. coli ACP may affect their recognition by the enzymes. Both enzymes were sensitive to KAS inhibitors cerulenin and thiolactomycin. These results represent important steps in characterizing KasA and KasB as targets for antimycobacterial drug discovery.


Asunto(s)
3-Oxoacil-(Proteína Transportadora de Acil) Sintasa/química , 3-Oxoacil-(Proteína Transportadora de Acil) Sintasa/aislamiento & purificación , Acetiltransferasas , Proteínas Bacterianas , Complejos Multienzimáticos , Mycobacterium tuberculosis/enzimología , 3-Oxoacil-(Proteína Transportadora de Acil) Sintasa/genética , Antibacterianos/farmacología , Antifúngicos/farmacología , Carbono/metabolismo , Cerulenina/farmacología , Cromatografía de Afinidad , Relación Dosis-Respuesta a Droga , Electroforesis en Gel de Poliacrilamida , Inhibidores Enzimáticos/farmacología , Escherichia coli/metabolismo , Acido Graso Sintasa Tipo II , Ácidos Grasos/biosíntesis , Eliminación de Gen , Concentración 50 Inhibidora , Cinética , Modelos Químicos , Ácidos Micólicos/metabolismo , Filogenia , Unión Proteica , Especificidad por Sustrato , Tiofenos/farmacología , Factores de Tiempo
12.
J Biol Chem ; 276(52): 48854-62, 2001 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-11677227

RESUMEN

The emb genes are conserved among different mycobacteria. In Mycobacterium smegmatis and Mycobacterium tuberculosis, they belong to an operon comprising three genes, embC, embA, and embB. The EmbB protein has been proposed to be the target of ethambutol, a drug which is known to inhibit the synthesis of the arabinan portion of the mycobacterial cell wall arabinogalactan (AG). To further define the role of EmbB protein in arabinan biosynthesis, embA, -B, and -C genes were inactivated individually by homologous recombination in M. smegmatis. All three mutants were viable, and among the three, the slowest growing embB(-) mutant encountered profound morphological changes and exhibited a higher sensitivity to hydrophobic drugs and detergents, presumably due to an increase in cell wall permeability. Furthermore, chemical analyses showed that there was a diminution in the arabinose content of arabinogalactan from the embA(-) and embB(-) mutants. Specifically, in comparison with the wild-type strain, the crucial terminal hexaarabinofuranosyl motif, which is a template for mycolylation, was altered in both embA(-) and embB(-) mutants. Detailed nuclear magnetic resonance studies coupled with enzyme digestion, chromatography, and mass spectrometry analyses revealed that the disaccharide beta-d-Ara(f)-(1-->2)-alpha-d-Ara(f) extension from the 3-position of the 3,5-linked alpha-d-Ara(f) residue is markedly diminished. As a consequence, a linear terminal beta-d-Ara(f)-(1-->2)-alpha-d-Ara(f)-(1-->5)-alpha-d-Ara(f)-(1-->5)-alpha-d-Ara(f) is formed, a motif which is a recognized, nonreducing terminal feature of lipoarabinomannan but not of normal AG. Upon complementation with the embB and embA wild-type genes, the phenotype of the mutants reverted to wild-type, in that normal AG was resynthesized. Our results clearly show that both EmbA and EmbB proteins are involved in the formation of the proper terminal hexaarabinofuranoside motif in AG, thus paving the way for future studies to identify the complete array of arabinosyltransferases involved in the synthesis of mycobacterial cell wall arabinan.


Asunto(s)
Galactanos/biosíntesis , Mycobacterium smegmatis/metabolismo , Pentosiltransferasa/metabolismo , Polisacáridos Bacterianos/biosíntesis , Pared Celular/química , Pared Celular/metabolismo , Galactanos/química , Espectrometría de Masas , Mutagénesis , Mycobacterium smegmatis/genética , Mycobacterium smegmatis/ultraestructura , Resonancia Magnética Nuclear Biomolecular , Pentosiltransferasa/genética , Polisacáridos Bacterianos/química
13.
J Clin Microbiol ; 39(11): 4210-2, 2001 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11682564

RESUMEN

A healthy 23-year-old man with fever and a tender mass in his right anterior neck was found to have a branchial cleft cyst infected with Bordetella bronchiseptica. Initial testing suggested a Brucella species, but further laboratory testing identified the organism definitively. B. bronchiseptica infection in healthy adults is an unusual event.


Asunto(s)
Infecciones por Bordetella/microbiología , Bordetella bronchiseptica/aislamiento & purificación , Branquioma/microbiología , Neoplasias de Cabeza y Cuello/microbiología , Inmunocompetencia , Adulto , Humanos , Masculino
14.
Glycobiology ; 11(9): 107R-118R, 2001 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11555614

RESUMEN

The compositional complexity of the mycobacterial cell envelope differentiates Mycobacterium species from most other prokaryotes. Historically, research in this area has focused on the elucidation of the structure of the mycobacterial cell envelope with the result that the structures of the mycolic acid-arabinogalactan-peptidoglycan complex from M. tuberculosis are fairly well understood. However, the current impetus for studying M. tuberculosis and other pathogenic mycobacteria is the need to identify targets for the development of new drugs. Therefore, emphasis has been shifting to the study of cell envelope biosynthesis and the identification of enzymes that are essential to the viability of M. tuberculosis. The publication of the complete M. tuberculosis genome in 1998 has greatly aided these studies. To date, thirteen enzymes involved in the synthesis of the arabinogalactan-peptidoglycan complex of M. tuberculosis have been identified and at least partially characterized. Eleven of these enzymes were reported subsequent to the publication of the M. tuberculosis genome, a clear indication of the rapid evolution of knowledge stimulated by the sequencing of the genome. In this article we review the current understanding of M. tuberculosis arabinogalactan-peptidoglycan structure and biosynthesis.


Asunto(s)
Galactanos/biosíntesis , Mycobacterium tuberculosis/metabolismo , Peptidoglicano/biosíntesis , Conformación de Carbohidratos , Peptidoglicano/química
15.
Genome Biol ; 2(8): REVIEWS1023, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11532219

RESUMEN

Comparison of the recently sequenced genome of the leprosy-causing pathogen Mycobacterium leprae with other mycobacterial genomes reveals a drastic gene reduction and decay in M. leprae affecting many metabolic areas, exemplified by the retention of a minimal set of genes required for cell-wall biosynthesis.


Asunto(s)
Genes Bacterianos/genética , Genoma Bacteriano , Mycobacterium leprae/genética , Mycobacterium leprae/metabolismo , Membrana Celular/química , Membrana Celular/metabolismo , Pared Celular/química , Pared Celular/metabolismo , Evolución Molecular , Genómica , Mycobacterium leprae/citología , Mycobacterium leprae/enzimología
16.
J Immunol ; 167(4): 2187-92, 2001 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-11490004

RESUMEN

Pathogenic mycobacteria are able to survive and proliferate in phagosomes within host macrophages (Mphi). This capability has been attributed in part to their cell wall, which consists of various unique lipids. Some of these are important in the host-pathogen interaction, such as resistance against microbicidal effector mechanisms and modulation of host cell functions, and/or are presented as Ags to T cells. Here we show that two lipids are released from the mycobacterial cell wall within the phagosome of infected Mphi and transported out of this compartment into intracellular vesicles. One of these lipids was identified as lysocardiolipin. Lysocardiolipin was generated through cleavage of mycobacterial cardiolipin by a Ca2+-independent phospholipase A2 present in Mphi lysosomes. This result indicates that lysosomal host cell enzymes can interact with released mycobacterial lipids to generate new products with a different intracellular distribution. This represents a novel pathway for the modification of bacterial lipid Ags.


Asunto(s)
Cardiolipinas/metabolismo , Lisosomas/enzimología , Macrófagos/enzimología , Macrófagos/microbiología , Mycobacterium bovis/metabolismo , Fagosomas/metabolismo , Fosfolipasas A/metabolismo , Animales , Transporte Biológico Activo , Calcio/fisiología , Células Cultivadas , Medios de Cultivo/metabolismo , Fosfolipasas A2 Grupo VI , Hidrólisis , Metabolismo de los Lípidos , Lisosomas/metabolismo , Macrófagos/metabolismo , Ratones , Mycobacterium bovis/crecimiento & desarrollo , Fosfolipasas A2
18.
Tuberculosis (Edinb) ; 81(3): 249-53, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11466037

RESUMEN

The objective was to apply the purified 38kDa protein antigen of Mycobacterium tuberculosis in ELISA to estimate the IgG, IgA and IgM antibody levels in sera and circulating immune complexes of tuberculosis patients. Sera from smear and culture positive tuberculosis patients were positive for anti 38kDa IgG, IgA and IgM antibodies, with a sensitivity of 61%, 30% and 10%, respectively, and with a specificity of 100% for IgG. The sensitivity of the test improved to a level of 68% for IgG+IgA and of 71.4% for IgG+IgA+IgM without significantly compromising the specificity (IgG of 100%, IgG+IgA of 96%, IgG+IgA+IgM of 90%). Among the smear, culture-negative but X-ray-positive cases, 60% were serum positive for IgG antibody, while in smear-negative but culture-positive cases, 54% were positive for IgG antibody. Measurement of 38kDa antibodies showed a greater than 95% sensitivity in smear and culture-positive, and smear-negative and culture-positive patients, through a combination of assays for serum IgG and circulating immune complex antibodies, while the specificity was 100%.


Asunto(s)
Anticuerpos Antibacterianos/inmunología , Especificidad de Anticuerpos , Antígenos Bacterianos/inmunología , Lipoproteínas/inmunología , Mycobacterium tuberculosis/inmunología , Tuberculosis Pulmonar/inmunología , Western Blotting , Electroforesis en Gel Bidimensional , Ensayo de Inmunoadsorción Enzimática , Humanos , Inmunoglobulina A/inmunología , Inmunoglobulina G/inmunología , Inmunoglobulina M/inmunología , Sensibilidad y Especificidad
19.
Biochim Biophys Acta ; 1532(1-2): 67-78, 2001 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-11420175

RESUMEN

Mycolic acids are generated in Mycobacterium tuberculosis as a result of the interaction of two fatty acid biosynthetic systems: the multifunctional polypeptide, FASI, in which the acyl carrier protein (ACP) domain forms an integral part of the polypeptide, and the dissociated FASII system, which is composed of monofunctional enzymes and a discrete ACP (AcpM). In order to characterize enzymes of the FASII system, large amounts of AcpM are required to generate substrates such as holo-AcpM, malonyl-AcpM and acyl-AcpM. The M. tuberculosis acpM gene was overexpressed in Escherichia coli and AcpM purified, yielding approximately 15-20 mg/l of culture. Analysis of AcpM by mass spectrometry, N-terminal sequencing, amino acid analysis, and gas chromatography indicated the presence of three species, apo-, holo-, and acyl-AcpM, the former comprising up to 65% of the total pool. The apo-AcpM was purified away from the in vivo generated holo- and acyl-forms, which were inseparable and heterogeneous with respect to acyl chain lengths. Once purified, we were able to convert apo-AcpM into holo- and acyl-forms. These procedures provide the means for the preparation of the large quantities of AcpM and derivatives needed for characterization of the purified enzymes of the mycobacterial FASII system.


Asunto(s)
Proteínas Bacterianas , Proteínas Portadoras/genética , Mycobacterium tuberculosis/química , Secuencia de Aminoácidos , Secuencia de Bases , Ligasas de Carbono-Azufre/metabolismo , Proteínas Portadoras/química , Proteínas Portadoras/aislamiento & purificación , Proteínas Portadoras/metabolismo , Cromatografía de Gases , Cartilla de ADN , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Espectrometría de Masas , Datos de Secuencia Molecular , Mycobacterium tuberculosis/enzimología , Homología de Secuencia de Aminoácido , Especificidad por Sustrato
20.
Bioorg Med Chem ; 9(4): 815-24, 2001 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-11354664

RESUMEN

A series of synthetic mannosides was screened in a cell-free system for their ability to act as acceptor substrates for mycobacterial mannosyltransferases. Evaluation of these compounds demonstrated the incorporation of [14C]Man from GDP-[14C]Man into a radiolabeled organic-soluble fraction and analysis by thin layer chromatography and autoradiography revealed the formation of two radiolabeled products. Each synthetic acceptor was capable of accepting one or two mannose residues, resulting in a major and a minor mannosylated product. Both products from each acceptor were isolated and their mass was confirmed by fast-atom bombardment-mass spectrometry (FABMS). Characterization of each mannosylated product by exo-glycosidase digestion. acetolysis and linkage analysis by gas chromatography mass spectrometry of partially per-O-methylated alditols, revealed only alpha1-6-linked products. In addition. the antibiotic amphomycin selectively inhibited the formation of mannosylated products suggesting polyprenolmonophosphate-mannose (C15 50-P-Man) was the immediate mannose donor in all mannosylation reactions observed. The ability of synthetic disaccharides to act as acceptor substrates in this system, is most likely due to the action of a mycobacterial polyprenol-P-Man:mannan alpha1-6 mannosyltransferase involved in the biosynthesis of linear alpha1-6-linked lipomannan.


Asunto(s)
Manósidos/química , Manosiltransferasas/metabolismo , Mycobacterium smegmatis/enzimología , Secuencia de Carbohidratos , Cromatografía de Gases y Espectrometría de Masas , Manósidos/síntesis química , Datos de Secuencia Molecular , Espectrometría de Masa Bombardeada por Átomos Veloces
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...