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2.
MedEdPORTAL ; 17: 11130, 2021 04 26.
Artículo en Inglés | MEDLINE | ID: mdl-33928186

RESUMEN

Introduction: Medical students' professional development includes their role as educators. Despite greater opportunities to join medical education curriculum development, medical students' engagement in these activities remains limited. A recent national study on student leadership in curricular change revealed a formal lack of leadership and training in medical education as significant barriers. Medical students' unawareness of how to disseminate curricula as educational scholarship and its value to their careers also restricts the fullness of their formation as educators. Methods: We designed a 3-hour, interactive, project-focused conference workshop for medical students without prior knowledge in curriculum development. Of participants, 64 worked in 10 groups creating medical curricula using Kern's six-step approach in student-facilitated breakout sessions. Completed group projects were presented, including brief action plans for transforming their work into scholarship. The workshop was evaluated using a mixed-methods approach. Results: Of survey respondents, 44 mostly medical students, faculty, and administrators from different institutions rated the workshop as a very positive experience, and the pacing of the breakout groups as effective. A notable increase in self-reported mastery, as measured by learning objectives aligned with Kern's six-step model, was recorded from student respondents as compared to faculty. A sense of readiness to participate in curricular decisions either at the home institution or in individual career paths was evident from narrative comments. Discussion: Our workshop provided medical students with a foundation in curriculum development and educational scholarship. Session design provided flexibility in the pace of breakout sessions and allowed in-depth discussion of educational topics.


Asunto(s)
Educación Médica , Estudiantes de Medicina , Curriculum , Becas , Humanos , Liderazgo
3.
Med Sci Educ ; 30(1): 609-615, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-34457712

RESUMEN

Although peer evaluations are essential to team-based learning, they can be problematic. Team activity debriefings (TAD) are advantageous because they focus on the team's problem-solving strategies and teamwork skills. Students (N = 100) who used both tools reported that TADs were more helpful in developing team cohesion, helping students understand the characteristics of well-functioning teams, and helping students work better as a team. Peer evaluations were more helpful in evaluating and improving their own contributions to the team. Using both tools may be the best way to foster teamwork skills and hold students accountable for making positive contributions to the team.

4.
Front Immunol ; 11: 595950, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33643285

RESUMEN

In recent years, the success of immunotherapy targeting immunoregulatory receptors (immune checkpoints) in cancer have generated enthusiastic support to target these receptors in a wide range of other immune related diseases. While the overwhelming focus has been on blockade of these inhibitory pathways to augment immunity, agonistic triggering via these receptors offers the promise of dampening pathogenic inflammatory responses. V-domain Ig suppressor of T cell activation (VISTA) has emerged as an immunoregulatory receptor with constitutive expression on both the T cell and myeloid compartments, and whose agonistic targeting has proven a unique avenue relative to other checkpoint pathways to suppress pathologies mediated by the innate arm of the immune system. VISTA agonistic targeting profoundly changes the phenotype of human monocytes towards an anti-inflammatory cell state, as highlighted by striking suppression of the canonical markers CD14 and Fcγr3a (CD16), and the almost complete suppression of both the interferon I (IFN-I) and antigen presentation pathways. The insights from these very recent studies highlight the impact of VISTA agonistic targeting of myeloid cells, and its potential therapeutic implications in the settings of hyperinflammatory responses such as cytokine storms, driven by dysregulated immune responses to viral infections (with a focus on COVID-19) and autoimmune diseases. Collectively, these findings suggest that the VISTA pathway plays a conserved, non-redundant role in myeloid cell function.


Asunto(s)
Antígenos B7/agonistas , COVID-19/patología , Síndrome de Liberación de Citoquinas/prevención & control , Células Mieloides/inmunología , Animales , Presentación de Antígeno/inmunología , Antígenos B7/antagonistas & inhibidores , Antígenos B7/inmunología , Linfocitos T CD4-Positivos/inmunología , Síndrome de Liberación de Citoquinas/inmunología , Síndrome de Liberación de Citoquinas/patología , Proteínas Ligadas a GPI/antagonistas & inhibidores , Humanos , Inmunoterapia , Interferón Tipo I/antagonistas & inhibidores , Receptores de Lipopolisacáridos/antagonistas & inhibidores , Activación de Linfocitos/inmunología , Ratones , Receptores de IgG/antagonistas & inhibidores , SARS-CoV-2/inmunología
5.
Arthritis Res Ther ; 19(1): 270, 2017 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-29216931

RESUMEN

BACKGROUND: In addition to activated T cells, the immune checkpoint inhibitor "V domain-containing Ig suppressor of T-cell activation" (VISTA) is expressed by myeloid cell types, including macrophages and neutrophils. The importance of VISTA expression by myeloid cells to antibody-induced arthritis and its potential for relevance in human disease was evaluated. METHODS: VISTA was immunolocalized in normal and arthritic human synovial tissue sections and synovial tissue lysates were subjected to western blot analysis. The collagen antibody-induced arthritis model (CAIA) was performed with DBA/1 J mice treated with antibodies against VISTA and with VISTA-deficient mice (V-KO). Total mRNA from arthritic joints, spleens, and cultured macrophages was analyzed with NanoString arrays. Cytokines secreted by splenic inflammatory macrophages were determined. In-vitro chemotaxis and signal transduction assays were performed with cultured macrophages. RESULTS: VISTA protein was localized to synovial membrane cells, neutrophils, and scattered cells in lymphocyte-rich foci and was detected by western blot analysis in normal synovium and synovium from rheumatoid arthritis patients. Deficiency of VISTA or treatment of mice with anti-VISTA monoclonal antibodies attenuated CAIA. Joint damage and MMP-3 expression were significantly reduced in V-KO mice. Surface expression of C5a receptor was reduced on monocytes, neutrophils, and cultured macrophages from V-KO. Upon Fc receptor engagement in vitro, gene expression by V-KO macrophages was altered profoundly compared to WT, including a significant induction of IL-1 receptor antagonist (IL1rn). CONCLUSIONS: VISTA expression supports immune-complex inflammation in CAIA and VISTA is expressed in human synovium. VISTA supports optimal responses to C5a and modulates macrophage responses to immune complexes.


Asunto(s)
Artritis Reumatoide/inmunología , Antígenos B7/inmunología , Regulación de la Expresión Génica/inmunología , Macrófagos/inmunología , Animales , Complejo Antígeno-Anticuerpo/inmunología , Artritis Experimental/inmunología , Antígenos B7/deficiencia , Humanos , Proteínas de la Membrana/deficiencia , Proteínas de la Membrana/inmunología , Ratones , Ratones Endogámicos DBA , Ratones Noqueados , Membrana Sinovial/inmunología
6.
Arthritis Rheumatol ; 69(4): 814-825, 2017 04.
Artículo en Inglés | MEDLINE | ID: mdl-27992697

RESUMEN

OBJECTIVE: The targeting of negative checkpoint regulators as a means of augmenting antitumor immune responses is now an increasingly used and remarkably effective approach to the treatment of several human malignancies. The negative checkpoint regulator VISTA (V-domain Ig-containing suppressor of T cell activation; also known as programmed death 1 homolog or as death domain 1α) suppresses T cell responses and regulates myeloid activities. We proposed that exploitation of the VISTA pathway is a novel strategy for the treatment of human autoimmune disease, and therefore we undertook this study to determine the impact of VISTA genetic deficiency on lupus development in a lupus-prone mouse strain. METHODS: To evaluate whether genetic deficiency of VISTA affects the development of lupus, we interbred VISTA-deficient mice with Sle1.Sle3 mice, a well-characterized model of systemic lupus erythematosus (SLE). RESULTS: We demonstrated that the development of proteinuria and glomerulonephritis in these mice, designated Sle1.Sle3 VISTA-/- mice, was greatly accelerated and more severe compared to that in Sle1.Sle3 and C57BL/6 VISTA-/- mice. Analysis of cells from Sle1.Sle3 VISTA-/- mice showed enhanced activation of splenic CD4+ T cells and myeloid cell populations. No increase in titers of autoantibodies was seen in Sle1.Sle3 VISTA-/- mice. Most striking was a significant increase in proinflammatory cytokines, chemokines, and interferon (IFN)-regulated genes associated with SLE, such as IFNα, IFNγ, tumor necrosis factor, interleukin-10, and CXCL10, in Sle1.Sle3 VISTA-/- mice. CONCLUSION: This study demonstrates for the first time that loss of VISTA in murine SLE exacerbates disease due to enhanced myeloid and T cell activation and cytokine production, including a robust IFNα signature, and supports a strategy of enhancement of the immunosuppressive activity of VISTA for the treatment of human lupus.


Asunto(s)
Nefritis Lúpica/etiología , Proteínas de la Membrana/deficiencia , Animales , Femenino , Proteínas de la Membrana/genética , Ratones
7.
Rheum Dis Clin North Am ; 42(1): 1-14, vii, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26611547

RESUMEN

Philip Hench, Edward Kendall, and Tadeus Reichstein received the Nobel Prize in medicine and physiology in 1950 for their "investigations of the hormones of the adrenal cortex." Hench and Kendall took compound E from the laboratory to the clinic to the Nobel Prize in a span of 2 years. This article examines the paths that led to the day when the first rheumatoid arthritis patient received cortisone, and from there to the 1950 Nobel Prize ceremony. The aftermath of this achievement is also discussed. Although there have been significant advances in corticosteroid preparations and use since 1950, the side effects remain daunting.


Asunto(s)
Antiinflamatorios/historia , Cortisona/historia , Descubrimiento de Drogas/historia , Corticoesteroides/historia , Antiinflamatorios/uso terapéutico , Artritis Reumatoide/tratamiento farmacológico , Cortisona/uso terapéutico , Historia del Siglo XX , Premio Nobel , Segunda Guerra Mundial
8.
Arthritis Res Ther ; 16(5): 469, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25606596

RESUMEN

Immune checkpoint regulators are critical modulators of the immune system, allowing the initiation of a productive immune response and preventing the onset of autoimmunity. Co-inhibitory and co-stimulatory immune checkpoint receptors are required for full T-cell activation and effector functions such as the production of cytokines. In autoimmune rheumatic diseases, impaired tolerance leads to the development of diseases such as rheumatoid arthritis, systemic lupus erythematosus, and Sjogren's syndrome. Targeting the pathways of the inhibitory immune checkpoint molecules CD152 (cytotoxic T lymphocyte antigen-4) and CD279 (programmed death-1) in cancer shows robust anti-tumor responses and tumor regression. This observation suggests that, in autoimmune diseases, the converse strategy of engaging these molecules may alleviate inflammation owing to the success of abatacept (CD152-Ig) in rheumatoid arthritis patients. We review the preclinical and clinical developments in targeting immune checkpoint regulators in rheumatic disease.


Asunto(s)
Receptores Coestimuladores e Inhibidores de Linfocitos T/inmunología , Inflamación/inmunología , Enfermedades Reumáticas/inmunología , Transducción de Señal/inmunología , Antirreumáticos/inmunología , Antirreumáticos/uso terapéutico , Humanos , Inflamación/tratamiento farmacológico , Activación de Linfocitos/efectos de los fármacos , Activación de Linfocitos/inmunología , Modelos Inmunológicos , Receptores de Antígenos de Linfocitos T/inmunología , Receptores de Antígenos de Linfocitos T/metabolismo , Enfermedades Reumáticas/tratamiento farmacológico , Transducción de Señal/efectos de los fármacos , Linfocitos T/efectos de los fármacos , Linfocitos T/inmunología , Linfocitos T/metabolismo
9.
Artículo en Inglés | MEDLINE | ID: mdl-22919622

RESUMEN

Polynucleotide phosphorylase (PNPase), encoded by the pnp gene, is known to degrade mRNA, mediating post-transcriptional regulation and may affect cellular functions. The role of PNPase is pleiotropic. As orthologs of the two major ribonucleases (RNase E and RNase II) of Escherichia coli are missing in the Campylobacter jejuni genome, in the current study the focus has been on the C. jejuni ortholog of PNPase. The effect of PNPase mutation on C. jejuni phenotypes and proteome was investigated. The inactivation of the pnp gene reduced significantly the ability of C. jejuni to adhere and to invade Ht-29 cells. Moreover, the pnp mutant strain exhibited a decrease in C. jejuni swimming ability and chick colonization. To explain effects of PNPase on C. jejuni 81-176 phenotype, the proteome of the pnp mutant and parental strains were compared. Overall, little variation in protein production was observed. Despite the predicted role of PNPase in mRNA regulation, the pnp mutation did not induce profound proteomic changes suggesting that other ribonucleases in C. jejuni might ensure this biological function in the absence of PNPase. Nevertheless, synthesis of proteins which are involved in virulence (LuxS, PEB3), motility (N-acetylneuraminic acid synthetase), stress-response (KatA, DnaK, Hsp90), and translation system (EF-Tu, EF-G) were modified in the pnp mutant strain suggesting a more specific role of PNPase in C. jejuni. In conclusion, PNPase deficiency induces limited but important consequences on C. jejuni biology that could explain swimming limitation, chick colonization delay, and the decrease of cell adhesion/invasion ability.


Asunto(s)
Campylobacter jejuni/enzimología , Campylobacter jejuni/metabolismo , Polirribonucleótido Nucleotidiltransferasa/metabolismo , Factores de Virulencia/metabolismo , Animales , Adhesión Bacteriana , Proteínas Bacterianas/análisis , Infecciones por Campylobacter/microbiología , Campylobacter jejuni/genética , Campylobacter jejuni/patogenicidad , Portador Sano/microbiología , Línea Celular , Pollos , Endocitosis , Células Epiteliales/microbiología , Tracto Gastrointestinal/microbiología , Eliminación de Gen , Regulación Bacteriana de la Expresión Génica , Prueba de Complementación Genética , Humanos , Locomoción , Polirribonucleótido Nucleotidiltransferasa/genética , Proteoma/análisis , Virulencia
11.
Ther Adv Chronic Dis ; 3(6): 271-86, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23342241

RESUMEN

Until recently, the last drug approved for the treatment of gout by the United States Food and Drug Administration was allopurinol in 1966. Since 2008, two new drugs for the treatment of gout, febuxostat and pegloticase, have been approved in the US. Febuxostat has been approved in the EU and pegloticase approval is anticipated. A new single-ingredient colchicine preparation is available in the US, and the treatment recommendations for the use of colchicine in acute gout have evolved, now favoring a low-dose regimen. Several other exciting drugs are in development. Herein, we review some of basic principles in the diagnosis and staging of gout. We then examine current treatment principles, with particular attention to febuxostat and pegloticase, offering suggestions as to where they might fit into a modern therapeutic algorithm for gout treatment. We then present available data on several exciting new agents in development, including interleukin-1 inhibitors, and relate them to advances in our understanding of gout pathogenesis. We conclude with some important nonpharmacologic principles for optimal management of this ancient and eminently treatable disease. Dedicated gout research, going on quietly in the background of other breathtaking advances in rheumatology, is now paying off. This comes at a time when the number of patients affected by gout continues to rise, mainly due to an epidemic of obesity. An effort to improve lifestyle choices as a society and better management of the disease by clinicians should have a positive impact on gout incidence and outcome in our lifetimes.

13.
Lancet ; 377(9760): 165-77, 2011 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-20719377

RESUMEN

The approval of febuxostat, a non-purine-analogue inhibitor of xanthine oxidase, by the European Medicines Agency and the US Food and Drug Administration heralds a new era in the treatment of gout. The use of modified uricases to rapidly reduce serum urate concentrations in patients with otherwise untreatable gout is progressing. Additionally, advances in our understanding of the transport of uric acid in the renal proximal tubule and the inflammatory response to monosodium urate crystals are translating into potential new treatments. In this Review, we focus on the clinical trials of febuxostat. We also review results from studies of pegloticase, a pegylated uricase in development, and we summarise data for several other pipeline drugs for gout, such as the selective uricosuric drug RDEA594 and various interleukin-1 inhibitors. Finally, we issue a word of caution about the proper use of the new drugs and the already available drugs for gout. At a time of important advances, we need to recommit ourselves to a rational approach to the treatment of gout.


Asunto(s)
Aprobación de Drogas , Supresores de la Gota/administración & dosificación , Supresores de la Gota/farmacología , Gota/tratamiento farmacológico , Tiazoles/administración & dosificación , Tiazoles/farmacología , Anticuerpos Monoclonales/farmacología , Anticuerpos Monoclonales Humanizados , Ensayos Clínicos como Asunto , Esquema de Medicación , Inhibidores Enzimáticos/farmacología , Europa (Continente) , Febuxostat , Gota/metabolismo , Supresores de la Gota/efectos adversos , Humanos , Proteína Antagonista del Receptor de Interleucina 1/farmacología , Interleucina-1/antagonistas & inhibidores , Polietilenglicoles/farmacología , Ensayos Clínicos Controlados Aleatorios como Asunto , Proteínas Recombinantes de Fusión/farmacología , Tiazoles/efectos adversos , Estados Unidos , United States Food and Drug Administration , Urato Oxidasa/farmacología , Ácido Úrico/metabolismo , Uricosúricos/farmacología , Xantina Oxidasa/antagonistas & inhibidores
14.
J Clin Rheumatol ; 15(7): 358-60, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20009973

RESUMEN

All-trans retinoic acid has revolutionized the treatment of acute promyelocytic leukemia, but this therapy is often complicated by the all-trans retinoic acid syndrome. Here we report a patient with newly diagnosed acute promyelocytic leukemia who developed acute focal myositis, synovitis, and possible vasculitis, after receiving all-trans retinoic acid therapy. We review the existing literature on this rare clinical entity, all-trans retinoic acid-induced myositis. This condition can manifest as fever, myalgia, arthralgia, and Sweet syndrome, accompanied by distinct magnetic resonance findings involving the lower extremity musculature. Treatment consists of discontinuation of the offending drug and often high dose corticosteroids.


Asunto(s)
Mononeuropatías/inducido químicamente , Miositis/inducido químicamente , Sinovitis/inducido químicamente , Tretinoina/efectos adversos , Corticoesteroides/uso terapéutico , Antineoplásicos/efectos adversos , Antineoplásicos/uso terapéutico , Femenino , Humanos , Leucemia Promielocítica Aguda/tratamiento farmacológico , Persona de Mediana Edad , Mononeuropatías/diagnóstico , Mononeuropatías/tratamiento farmacológico , Miositis/diagnóstico , Miositis/tratamiento farmacológico , Sinovitis/diagnóstico , Sinovitis/tratamiento farmacológico , Resultado del Tratamiento , Tretinoina/uso terapéutico , Privación de Tratamiento
15.
Appl Environ Microbiol ; 75(23): 7310-8, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19801468

RESUMEN

Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide. Infection generally occurs after ingestion of contaminated poultry products, usually conserved at low temperatures. The mechanisms promoting survival of C. jejuni in the cold remain poorly understood despite several investigations. The present study provides insight into the survival mechanism by establishing the involvement of polynucleotide phosphorylase (PNPase), a 3'-5' exoribonuclease with multiple biological functions in cold survival. The role of PNPase was demonstrated genetically using strains with altered pnp genes (which encode PNPase) created in C. jejuni F38011 and C. jejuni 81-76 backgrounds. Survival assays carried out at low temperatures (4 and 10 degrees C) revealed a difference of 3 log CFU/ml between the wild-type and the pnp deletion (Deltapnp) strains. This did not result from a general requirement for PNPase because survival rates of the strains were similar at higher growth temperatures (37 or 42 degrees C). trans-Complementation with plasmid pNH04 carrying the pnp gene under the control of its natural promoter restored the cold survival phenotype to the pnp deletion strains (at 4 and 10 degrees C) but not to the same level as the wild type. In this study we demonstrate the role of PNPase in low-temperature survival of C. jejuni and therefore attribute a novel biological function to PNPase directly related to human health.


Asunto(s)
Proteínas Bacterianas/metabolismo , Campylobacter jejuni/fisiología , Frío , Viabilidad Microbiana , Polirribonucleótido Nucleotidiltransferasa/metabolismo , Estrés Fisiológico , Proteínas Bacterianas/genética , Recuento de Colonia Microbiana , Eliminación de Gen , Prueba de Complementación Genética , Humanos , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Polirribonucleótido Nucleotidiltransferasa/genética
16.
J Clin Rheumatol ; 15(6): 295-9, 2009 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19734736

RESUMEN

Aortitis is typically a chronic, progressive disease manifestation associated with large vessel vasculitidies, most notably giant cell, Takayasu arteritis, and a newly described entity, isolated aortitis. The aortitis may lead to aneurysm formation and symptoms associated with branch vessel occlusion in these diseases, but aortic dissection is rare and usually a late complication of smoldering, incompletely treated disease. We present a case of aortitis in a previously healthy 39-year-old man who succumbed to aortic dissection hours after the onset of symptoms. No aneurysm or fibrosis was found on postmortem examination. The inflammation was characterized by disruption of the media with patchy transmural chronic and focally acute inflammatory infiltrate. We review case reports of other individuals with aortitis, who initially or very early in their course presented with aortic dissection in the absence of known rheumatic disease and most without evidence of aneurysm formation. We believe that this represents a process characterized by an aggressive vasculitis of the aorta with its own clinical features, a fulminant variety of isolated aortitis.


Asunto(s)
Rotura de la Aorta/diagnóstico , Rotura de la Aorta/etiología , Aortitis/complicaciones , Adulto , Aorta/patología , Rotura de la Aorta/patología , Resultado Fatal , Humanos , Masculino
17.
Biochemistry ; 48(9): 2012-20, 2009 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-19219992

RESUMEN

Escherichia coli polynucleotide phosphorylase (PNPase) primarily functions in RNA degradation. It is an exoribonuclease and integral component of the multienzyme RNA degradosome complex [Carpousis et al. (1994) Cell 76, 889]. PNPase was previously shown to specifically bind a synthetic RNA containing the oxidative lesion 8-hydroxyguanine (8-oxoG) [Hayakawa et al. (2001) Biochemistry 40, 9977], suggesting a possible role in removing oxidatively damaged RNA. Here we show that PNPase binds to RNA molecules of natural sequence that were oxidatively damaged by treatment with hydrogen peroxide (H(2)O(2)) postsynthetically. PNPase bound oxidized RNA with higher affinity than untreated RNA of the same sequence, raising the possibility that it may act against a wide variety of lesions. The importance of such a protective role is illustrated by the observation that, under conditions known to cause oxidative damage to cytoplasmic components, PNPase-deficient cells are less viable than wild-type cells. Further, when challenged with H(2)O(2), PNPase-deficient cells accumulate 8-oxoG in cellular RNA to a greater extent than wild-type cells, suggesting that this RNase functions in minimizing oxidized RNA in vivo. Introducing the pnp gene encoding PNPase rescues defects in growth and RNA quality of the pnp mutant cells. Our results also suggest that protection against oxidative stress is an intrinsic function of PNPase because association with the RNA degradosome or with RNA helicase B (RhlB) is not required.


Asunto(s)
Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimología , Estrés Oxidativo , Polirribonucleótido Nucleotidiltransferasa/metabolismo , 8-Hidroxi-2'-Desoxicoguanosina , Secuencia de Bases , Unión Competitiva , Desoxiguanosina/análogos & derivados , Desoxiguanosina/metabolismo , Electroforesis en Gel de Poliacrilamida , Escherichia coli/genética , Escherichia coli/crecimiento & desarrollo , Proteínas de Escherichia coli/genética , Prueba de Complementación Genética , Guanina/análogos & derivados , Guanina/metabolismo , Peróxido de Hidrógeno/farmacología , Viabilidad Microbiana/efectos de los fármacos , Mutación , Oligonucleótidos/genética , Oligonucleótidos/metabolismo , Oxidación-Reducción , Paraquat/farmacología , Polirribonucleótido Nucleotidiltransferasa/genética , Unión Proteica , ARN Bacteriano/metabolismo
18.
Microbiology (Reading) ; 155(Pt 3): 979-988, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19246768

RESUMEN

Although infection with Campylobacter jejuni is one of the leading causes of gastroenteritis worldwide, relatively little is known about the factors that are required to elicit a protective immune response. The need for a vaccine against this pathogen is well recognized and a number of vaccine candidates have been tested with varying degrees of success; however, there is still a lack of a suitable vaccine. To gain a better understanding of the outer-membrane protein components of this organism, a 'gold standard' method to purify the outer membrane is needed. Therefore, we attempted to develop a robust and reliable method which resulted in a pure outer-membrane fraction. A total of nine methodologies were examined and analysed by SDS-PAGE and immunoblotting using subcellular markers for the cytoplasm, cytoplasmic membrane and outer membrane. We found that glycine extraction, differential detergent extraction using Triton X-100, serial extraction using 1 M Tris pH 7, spheroplasting by lysozyme and sonication, and carbonate extraction did not produce pure outer-membrane preparations. However, we identified three methods that provided outer-membrane fractions free from subcellular contamination. Isopycnic centrifugation using a 30-60 % sucrose gradient produced seven fractions free from cytoplasmic or cytoplasmic membrane contamination; however, these fractions did not correspond as well as expected with the typical outer-membrane-associated peak (e.g. Escherichia coli or Salmonella). The spheroplast method using lysozyme alone also resulted in pure outer-membrane fraction, as did carbonate washing of this sample. The extraction of outer membranes using N-lauroylsarcosine (Sarkosyl) produced the purest and most reproducible sample. These outer-membrane preparations will be useful for future studies aimed at identifying C. jejuni surface proteins as vaccine components.


Asunto(s)
Proteínas de la Membrana Bacteriana Externa/aislamiento & purificación , Campylobacter jejuni/química , Sarcosina/análogos & derivados , Proteínas de la Membrana Bacteriana Externa/química , Centrifugación por Gradiente de Densidad , Electroforesis en Gel de Poliacrilamida/métodos , Octoxinol/química , Reproducibilidad de los Resultados , Sarcosina/química , Sensibilidad y Especificidad
20.
Mol Microbiol ; 68(2): 474-91, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18284594

RESUMEN

Campylobacter jejuni is a gastrointestinal pathogen of humans but can asymptomatically colonize the avian gut. C. jejuni therefore grows at both 37 degrees C and 42 degrees C, the internal temperatures of humans and birds respectively. Microarray and proteomic studies on temperature regulation in C. jejuni strain 81-176 revealed the upregulation at 42 degrees C of two proteins, Cj0414 and Cj0415, orthologous to gluconate dehydrogenase (GADH) from Pectobacterium cypripedii. 81-176 demonstrated GADH activity, converting d-gluconate to 2-keto-d-gluconate, that was higher at 42 degrees C than at 37 degrees C. In contrast, cj0414 and cj0415 mutants lacked GADH activity. Wild-type but not cj0415 mutant bacteria exhibited gluconate-dependent respiration. Neither strain grew in defined media with d-gluconate or 2-keto-d-gluconate as a sole carbon source, revealing that gluconate was used as an electron donor rather than as a carbon source. When administered to chicks individually or in competition with wild-type, the cj0415 mutant was impaired in establishing colonization. In contrast, there were few significant differences in colonization of BALB/c-ByJ mice in single or mixed infections. These results suggest that the ability of C. jejuni to use gluconate as an electron donor via GADH activity is an important metabolic characteristic that is required for full colonization of avian but not mammalian hosts.


Asunto(s)
Proteínas Bacterianas/metabolismo , Campylobacter jejuni/enzimología , Gluconatos/metabolismo , Oxidorreductasas/metabolismo , Animales , Proteínas Bacterianas/genética , Infecciones por Campylobacter/microbiología , Campylobacter jejuni/química , Campylobacter jejuni/crecimiento & desarrollo , Campylobacter jejuni/metabolismo , Ciego/microbiología , Pollos , Recuento de Colonia Microbiana , Electroforesis en Gel Bidimensional , Eliminación de Gen , Perfilación de la Expresión Génica , Ratones , Ratones Endogámicos BALB C , Análisis de Secuencia por Matrices de Oligonucleótidos , Oxidorreductasas/genética , Oxígeno/metabolismo , Pectobacterium/enzimología , Pectobacterium/genética , Proteoma/análisis , Homología de Secuencia de Aminoácido , Temperatura , Factores de Virulencia/genética , Factores de Virulencia/metabolismo
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