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1.
J Med Vasc ; 46(4): 163-170, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34238510

RESUMEN

INTRODUCTION: The COVID-19 pandemic is associated with a high incidence of venous thromboembolism questioning the utility of a systematic screening for deep venous thrombosis (DVT) in hospitalised patients. METHODS: In this prospective bicentric controlled study, 4-point ultrasound using a pocket device was used to screen for DVT, in patients with SARS-CoV-2 infection and controls admitted for acute medical illness not related to COVID-19 hospitalised in general ward, in order to assess the utility of a routine screening and to estimate the prevalence of VTE among those patients. RESULTS: Between April and May 2020, 135 patients were screened, 69 in the COVID+ group and 66 in the control one. There was no significant difference in the rate of proximal DVT between the two groups (2.2% vs. 1.5%; P=0.52), despite the high rate of PE diagnosed among COVID-19 infected patients (10.1% vs. 1.5%, P=0.063). No isolated DVT was detected, 37.5% of PE was associated with DVT. Mortality (7.2% vs. 1.5%) was not different (P=0.21) between COVID-19 patients and controls. CONCLUSION: The systematic screening for proximal DVT was not found to be relevant among COVID-19 patients hospitalized in general ward despite the increase of VTE among this population. Further studies are needed to confirm the hypothesis of a local pulmonary thrombosis which may lead to new therapeutic targets.


Asunto(s)
COVID-19/epidemiología , Programas de Detección Diagnóstica , Hospitalización , Embolia Pulmonar/diagnóstico por imagen , Ultrasonografía , Trombosis de la Vena/diagnóstico por imagen , Anciano , Anciano de 80 o más Años , COVID-19/diagnóstico , COVID-19/mortalidad , Estudios de Casos y Controles , Femenino , Francia/epidemiología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Prevalencia , Estudios Prospectivos , Embolia Pulmonar/epidemiología , Medición de Riesgo , Factores de Riesgo , Procedimientos Innecesarios , Trombosis de la Vena/epidemiología
2.
Rev Med Interne ; 41(12): 838-842, 2020 Dec.
Artículo en Francés | MEDLINE | ID: mdl-32753245

RESUMEN

Acquired angioedema with C1-inhibitor deficiency is a rare and peculiar entity belonging to the spectrum of bradykinin angioedemas. It usually occurs in subjects over 60 years old, and is mostly associated with a B-cell lymphoid hemopathy or a monoclonal gammopathy. The diagnosis relies on at least one angioedema episode, lasting more than 24 h, and on the decrease of functional C1-inhibitor. Low C1q is observed in 90% of patients, and an anti C1-inhibitor antibody is found in 50% of patients. The treatment of severe attacks relies on icatibant or C1-inhibitor perfusions. Long term prophylaxis in patients with frequent attacks requires treatment of the associated hemopathy if so. In case of idiopathic angioedema, tranexamic acid and danazol may be used, provided that there is-no thrombophilia; as well as rituximab as second-line treatment. Inhibitors of kallikrein still need to be evaluated in this therapeutic indication.


Asunto(s)
Angioedema/diagnóstico , Angioedema/terapia , Angioedemas Hereditarios/diagnóstico , Angioedemas Hereditarios/terapia , Angioedema/epidemiología , Angioedema/etiología , Angioedemas Hereditarios/complicaciones , Angioedemas Hereditarios/epidemiología , Bradiquinina/análogos & derivados , Bradiquinina/uso terapéutico , Quimioprevención/métodos , Quimioprevención/normas , Comorbilidad , Diagnóstico Diferencial , Técnicas y Procedimientos Diagnósticos/normas , Francia , Enfermedades Hematológicas/complicaciones , Enfermedades Hematológicas/diagnóstico , Enfermedades Hematológicas/epidemiología , Enfermedades Hematológicas/terapia , Humanos , Medicina Interna/organización & administración , Medicina Interna/normas , Persona de Mediana Edad , Estándares de Referencia , Rituximab/uso terapéutico , Sociedades Médicas/normas , Ácido Tranexámico/uso terapéutico
3.
J Chem Ecol ; 46(8): 782-792, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31956921

RESUMEN

Epiphytic bacteria have been shown to affect the composition of volatiles released by plants and as a consequence the behavior of other organisms towards the plant, such as herbivores and/or pathogens. In this study, we explored the effects of inoculation with three bacterial strains, namely Pseudomonas syringae, Pantoea ananatis, and Pseudomonas putida, on the composition of leaf volatile organic compounds (VOCs) emitted by bean plants (Phaseolus vulgaris L.). In addition, we examined responses of the two-spotted spider mite (Tetranychus urticae) to VOCs by measuring leaf damage and oviposition of female adults after bacterial inoculation. Colonized bean plants emitted different VOCs depending on the bacterial inoculum. The quantities of volatiles 1-undecanol and (Z)-3-hexen-1-ol significantly increased after P. syringae inoculation, while methyl salicylate and anisole increased in response to P. ananatis. T. urticae females preferred control plants over plants inoculated with P. syringae or P. putida in olfactometer assays, while no particular preference was recorded in the presence of P. ananatis. Furthermore, leaf damage caused by spider mites was 3-fold lower in plants inoculated with P. syringae than in control plants and plants inoculated with P. ananatis. Subsequently, the number of eggs laid on leaves inoculated with P. syringae was significantly lower than on those inoculated with P. ananatis or on the control ones. Moreover, a significantly higher number of spider mites selected methyl salicylate odor source over 1-undecanol, in a two-choice bioassay. The results demonstrate the bacterial involvement in plant-arthropod interactions and suggest further investigation on the potential use of bacteria as biocontrol agents in agriculture.


Asunto(s)
Pantoea/fisiología , Phaseolus/química , Pseudomonas putida/fisiología , Pseudomonas syringae/fisiología , Tetranychidae/fisiología , Compuestos Orgánicos Volátiles/metabolismo , Animales , Femenino , Oviposición , Hojas de la Planta/química
4.
Lupus ; 29(2): 157-164, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31948351

RESUMEN

INTRODUCTION: Antiphospholipid syndrome (APS) is associated with greater atherothrombotic risk and endothelial dysfunction, suggesting that endothelial glycocalyx is impaired in this disease. OBJECTIVES: The aim was to investigate the endothelial glycocalyx and the relationship between glycocalyx markers, endothelial dysfunction parameters and atherosclerotic markers in APS. METHODS: A total of 15 primary arterial APS patients and healthy controls were included in the study. Glycocalyx was assessed in both groups by sublingual sidestream dark field imaging and syndecan-1 plasma level. Endothelial function was evaluated by brachial artery flow-mediated dilatation (FMD) and early atherosclerosis by carotid intima media thickness (IMT). Thrombotic profile was also performed by measuring the plasma level of the tissue factor (TF). RESULTS: APS patients had significantly increased syndecan-1 plasma level 38.6 ± 5.0 pg/ml vs. 19.1 ± 3.5 pg/ml; p < 0.01 and a reduced glycocalyx thickness 0.26 ± 0.03 µm vs. 0.75 ± 0.07 µm; p < 0.01 compared with control. FMD was impaired in APS patients compared with control, 5.68% ± 0.42 vs. 8.29 ± 0.30, p < 0.01, respectively. IMT was significantly increased in APS patients compared with control, 0.52 ± 0.13 mm vs. 0.40 ± 0.06 mm, p < 0.01, respectively. Soluble TF, thiobarbituric acid-reactive substances levels were increased in the sera from APS patients compared with control. CONCLUSIONS: This preliminary study supports, for the first time, that in APS patients endothelial glycocalyx is impaired, which could lead to thrombosis, endothelial dysfunction and early atherosclerosis.


Asunto(s)
Síndrome Antifosfolípido/fisiopatología , Aterosclerosis/etiología , Autoanticuerpos/inmunología , Endotelio Vascular/fisiopatología , Glicocálix/patología , Trombosis/etiología , Adolescente , Adulto , Anciano , Síndrome Antifosfolípido/sangre , Síndrome Antifosfolípido/inmunología , Biomarcadores/sangre , Arteria Braquial/diagnóstico por imagen , Arterias Carótidas/diagnóstico por imagen , Grosor Intima-Media Carotídeo , Estudios de Casos y Controles , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Sindecano-1/sangre , Tromboplastina/análisis , Vasodilatación , Adulto Joven
6.
Rev Med Interne ; 41(2): 106-110, 2020 Feb.
Artículo en Francés | MEDLINE | ID: mdl-31732197

RESUMEN

Giant cell arteritis is the most common primary vasculitis of large-vessel occurring in subjects over 50 years of age. Many imaging techniques has been evaluated to improve the diagnosis of giant cell arteritis. Among these imaging techniques, ultrasound has shown good performances to detect inflammatory involvement of the temporal arteries as well as branches of the aorta. Several publications and recent EULAR recommendations have emhasized the place of this tool in the diagnosis of giant cell arteritis.


Asunto(s)
Arteritis de Células Gigantes/diagnóstico , Ultrasonografía Doppler en Color/métodos , Diagnóstico por Imagen/historia , Diagnóstico por Imagen/métodos , Diagnóstico por Imagen/normas , Arteritis de Células Gigantes/diagnóstico por imagen , Historia del Siglo XX , Historia del Siglo XXI , Humanos , Guías de Práctica Clínica como Asunto , Valor Predictivo de las Pruebas , Ultrasonografía Doppler en Color/historia , Ultrasonografía Doppler en Color/normas
7.
Rev Med Interne ; 40(7): 453-456, 2019 Jul.
Artículo en Francés | MEDLINE | ID: mdl-31040049

RESUMEN

Carpal tunnel syndrome is a common peripheral neuropathy, usually idiopathic or post-traumatic due to the compression of the median nerve. Numbness and paresthesias in the median nerve distribution are the most common symptoms associated with this condition. Persistent median artery is a rare anatomic variation, thrombosis of this additional artery can be responsible for an acute carpal tunnel syndrome, and patients frequently complain about coldness and acute hand swelling. These unusual features must lead clinicians to think of a vascular cause. The diagnosis can be easily confirmed by using ultrasound doppler, but CT-scan and MRI are sometimes helpful. We describe 2 cases of acute carpal tunnel syndrome due to thrombosed persistent median artery, including a case of thromboangiitis obliterans. These thrombosis might also be due to traumatic causes. No guidelines are currently available to help physicians for the management of carpal tunnel syndrome from thrombosed persistent median artery. Antiplatelet therapy, statin, anticoagulant might be helpful, and surgery has sometimes be reported as effective.


Asunto(s)
Arterias/patología , Síndrome del Túnel Carpiano/diagnóstico , Síndrome del Túnel Carpiano/etiología , Nervio Mediano/irrigación sanguínea , Trombosis/complicaciones , Trombosis/diagnóstico , Enfermedad Aguda , Adulto , Femenino , Humanos , Masculino , Nervio Mediano/patología , Neuropatía Mediana/complicaciones , Neuropatía Mediana/patología , Persona de Mediana Edad
8.
Rev Med Interne ; 40(6): 351-354, 2019 Jun.
Artículo en Francés | MEDLINE | ID: mdl-30905593

RESUMEN

PURPOSE: Antiphospholipid syndrome (APS) is a clinico-biological syndrome, which associates vascular injury and persisting antiphospholipid antibodies (aPL). Patients with clinical symptoms of APS but without aPL are defined as "seronegative APS" (SNAPS). The aim of this study was to evaluate antiphosphatidylethanolamine antibody (aPE) investigation in patients with SNAPS suspicion. METHODS: This retrospective study was conducted in patients with SNAPS suspicion. A homemade enzyme-linked immunosorbent assay (ELISA) was used to search for aPE. The results of this homemade method were compared with those from a global screening ELISA. RESULTS: Two hundred twenty-eight patients with SNAPS suspicion were included. Among them, 58.3% had a thrombotic event. The homemade ELISA found positive persisting aPE in 23 patients (10%): 15 with a thrombotic event, 6 with obstetrical morbidity and 2 with a combined event. The global screening ELISA was positive in only 11 of these 23 patients (47.8%). CONCLUSION: These results suggest the implication of aPE in SNAPS.


Asunto(s)
Anticuerpos Antifosfolípidos/sangre , Síndrome Antifosfolípido/sangre , Síndrome Antifosfolípido/inmunología , Fosfatidiletanolaminas/inmunología , Adulto , Anciano , Síndrome Antifosfolípido/diagnóstico , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos
11.
Rev Med Interne ; 37(1): 58-61, 2016 Jan.
Artículo en Francés | MEDLINE | ID: mdl-26096756

RESUMEN

INTRODUCTION: While in most countries warfarin is the preferred anti-vitamin K, fluindione, a molecule with a prolonged half-life remains largely prescribed in France. Some of its side effects, including immuno-allergic complications, remain poorly understood. CASE REPORT: A 77-year-old woman presented with a febrile severe neutropenia of immunoallergic mechanism with a favourable outcome associated with fluindione, introduced 25 days earlier for the treatment of atrial fibrillation. CONCLUSION: This rare side effect is a reminder of the importance of biological monitoring in the first weeks following the introduction of fluindione and key diagnostic elements and therapeutic aspects of iatrogenic agranulocytosis.


Asunto(s)
Agranulocitosis/inducido químicamente , Anticoagulantes/efectos adversos , Fenindiona/análogos & derivados , Anciano , Agranulocitosis/patología , Neutropenia Febril Inducida por Quimioterapia/patología , Hipersensibilidad a las Drogas/patología , Femenino , Francia , Humanos , Fenindiona/efectos adversos
12.
Rev Med Interne ; 36(12): 813-7, 2015 Dec.
Artículo en Francés | MEDLINE | ID: mdl-26320364

RESUMEN

PURPOSE: More than one million patients received an oral anticoagulant treatment in France. This medication is the first aetiology of iatrogenic events. Recently, direct oral anticoagulant (DOA) provided efficacy and safety in the treatment of atrial fibrillation and venous thromboembolic events. Given the growing increase in the prescription of these molecules, with many advantages but also disadvantages, it seemed interesting to assess in routine hospital medical practice, the proportion of patients for which the initiation of AOD could be safe. METHODS: This prospective, observational study was conducted in the department of internal medicine from October 2012 and September 2013. All inpatients receiving oral anticoagulant treatment have been included. Demographic data, indication of anticoagulant treatment, contraindications and interactions have been reported. From these information, we have established the percentage of patients who could benefit from DOA safely and securely. RESULTS: Two hundred and ninety inpatients were included with a mean age of 76.3±15.2 years old. Atrial fibrillation and thromboembolic venous disease were the most prevalent indications of anticoagulant treatments (67.2% and 22.4% of cases respectively). Among all patients, 260 had an indication of DOA (89.7%), authorized by the French National health agency. Eighty percent had both indication and no contraindication for DOA. However, only 53.1% of patients neither had drug-drug interaction. Main contraindications were severe renal failure (clearance<30mL/min) in 10.7% of cases, and recent history of gastric ulcer in 15.3% of cases. The most frequent interactions with DOA were antiplatelet agent (14.5%) and amiodarone (11.6%). Almost two thirds of inpatients (65.1%) had at least one drug-drug interaction with VKA. CONCLUSION: These results, coming from "real life", provide that only 53.1% of inpatients under anticoagulants could receive DOA safely. Caution is warranted, and VKA still have a preponderant role among anticoagulant drugs.


Asunto(s)
Anticoagulantes/administración & dosificación , Tromboembolia/prevención & control , Administración Oral , Anciano , Fibrilación Atrial/complicaciones , Femenino , Humanos , Masculino , Estudios Prospectivos , Tromboembolia/etiología , Vitamina K/antagonistas & inhibidores
13.
Microvasc Res ; 99: 72-7, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25794968

RESUMEN

BACKGROUND: Initial morphological and functional markers of systemic sclerosis (SSc) are evidenced in microvascular structural damage. However, nailfold videocapillaroscopy (NVC) explores only morphological abnormalities. Sidestream Dark Field (SDF) imaging of sublingual microcirculation enables assessment of both morphological and functional capillary impairment and allows measurement of the glycocalyx layer, which is an indicator of endothelial dysfunction. OBJECTIVE: To describe and validate sublingual abnormalities assessed by SDF device in comparison with NVC findings and to measure the thickness of the glycocalyx layer. METHODS: From February to May 2014, 26 subjects (16 SSc patients and 10 healthy controls) underwent standardised NVC and SDF imaging of sublingual microcirculation. Glycocalyx thickness was also measured. RESULTS: Capillary density and percentage of perfused vessels were significantly reduced in patients with SSc (n = 13) compared to controls. Correlation between nailfold capillary density assessed by NVC and sublingual capillary density assessed by SDF was observed (r(2) = 0.59; P = 0.023). According to the NVC pattern, patients with "active" disease experienced greater reduction in capillary density than patients with "late" disease as suggested by the de Backer score (9.17 ± 0.81 vs 10.86 ± 1.19; P = 0.03). Additionally, the decrease in glycocalyx thickness was measured in SSc patients (n = 13) compared to controls (n = 10) (0.41 ± 0.03 versus 0.76 ± 0.29 P = 0.003). CONCLUSION: Our results suggest for the first time in SSc, that sublingual microcirculation and glycocalyx are impaired and that SDF imaging findings correlate with those of NVC. Nevertheless, further studies are required for the validation of our preliminary results.


Asunto(s)
Microcirculación , Suelo de la Boca/irrigación sanguínea , Esclerodermia Sistémica/fisiopatología , Lengua/irrigación sanguínea , Adulto , Anciano , Capilares/patología , Estudios de Casos y Controles , Femenino , Glicocálix/química , Humanos , Masculino , Angioscopía Microscópica , Persona de Mediana Edad , Uñas/irrigación sanguínea , Enfermedad de Raynaud/fisiopatología , Reproducibilidad de los Resultados
14.
Rev Med Interne ; 36(6): 381-5, 2015 Jun.
Artículo en Francés | MEDLINE | ID: mdl-25554399

RESUMEN

INTRODUCTION: Venous thromboembolism and dehydration are frequent conditions in elderly. The objective of this study was to assess the prevalence of dehydration in patients aged over 70 years suspected of deep vein thrombosis (DVT). METHODS: This is a prospective observational study that included patients aged over 70 years and suspected of deep vein thrombosis. Clinical and biological dehydration was diagnosed on the presence of a skin fold, a weight loss≥5%, a thirst, a plasmatic osmolality>295 mOsm/L or blood urea nitrogen/creatinine ratio>20. RESULTS: One hundred and forty-four patients (mean age 81.8±5.8 years) were included. A diagnosis of DVT was retained in 97 patients. Clinical dehydration was not more frequent in the DVT+ group (37.2% vs 35.1%). At baseline, 69.1% of DVT+ patients and 53.2% of DVT- patients had a plasma osmolality greater than 295 mosm/L (NS). BUN/creatinine ratio greater than 20 was found in 58.8% of DVT+ patients and 72.3% of DVT- patients (NS). Clinical and biological dehydration was present in 28.6% of DVT+ patients and in 33.3% of DVT- patients (NS). The positive predictive value of the Wells score≥3 was 86.5%, and negative predictive value of a Wells score≤0 was 85%. CONCLUSION: The presence of dehydration does not appear predictive of the occurrence of DVT and does not influence the statistical performance of the Wells score in elderly patients.


Asunto(s)
Deshidratación/epidemiología , Trombosis de la Vena/complicaciones , Anciano , Anciano de 80 o más Años , Deshidratación/complicaciones , Femenino , Humanos , Masculino , Valor Predictivo de las Pruebas , Prevalencia , Estudios Prospectivos
17.
Rev Med Interne ; 35(8): 512-23, 2014 Aug.
Artículo en Francés | MEDLINE | ID: mdl-24412013

RESUMEN

Numerous autoimmune-inflammatory rheumatic diseases have been associated with accelerated atherosclerosis or other types of vasculopathy leading to an increase in cardiovascular disease incidence. In addition to traditional cardiovascular risk factors, endothelial dysfunction is an important early event in the pathogenesis of atherosclerosis, contributing to plaque initiation and progression. Endothelial dysfunction is characterized by a shift of the actions of the endothelium toward reduced vasodilation, a proinflammatory and a proadhesive state, and prothrombic properties. Therefore, assessment of endothelial dysfunction targets this vascular phenotype using several biological markers as indicators of endothelial dysfunction. Measurements of soluble adhesion molecules (ICAM-1, VCAM-1, E-selectin), pro-thrombotic factors (thrombomodulin, von Willebrand factor, plasminogen activator inhibitor-1) and inflammatory cytokines are most often performed. Regarding the functional assessment of the endothelium, the flow-mediated dilatation of conduit arteries is a non-invasive method widely used in pathophysiological and interventional studies. In this review, we will briefly review the most relevant information upon endothelial dysfunction mechanisms and explorations. We will summarize the similarities and differences in the biological and functional assessments of the endothelium in different autoimmune diseases.


Asunto(s)
Enfermedades Autoinmunes/fisiopatología , Enfermedades Cardiovasculares/fisiopatología , Endotelio Vascular/fisiopatología , Síndrome Antifosfolípido/fisiopatología , Aterosclerosis/fisiopatología , Enfermedades Autoinmunes/sangre , Enfermedades Autoinmunes/epidemiología , Enfermedades Autoinmunes/patología , Biomarcadores/sangre , Enfermedades Cardiovasculares/sangre , Enfermedades Cardiovasculares/epidemiología , Enfermedades Cardiovasculares/patología , Citocinas/sangre , Progresión de la Enfermedad , Selectina E/sangre , Francia/epidemiología , Humanos , Incidencia , Molécula 1 de Adhesión Intercelular/sangre , Inhibidor 1 de Activador Plasminogénico/sangre , Índice de Severidad de la Enfermedad , Trombomodulina/sangre , Molécula 1 de Adhesión Celular Vascular/sangre , Factor de von Willebrand/metabolismo
18.
Rev Med Interne ; 30(1): 53-7, 2009 Jan.
Artículo en Francés | MEDLINE | ID: mdl-18835653

RESUMEN

INTRODUCTION: Bilateral hilar lymphadenopathy, with or without lung parenchymal infiltrates, is the most common radiographic finding in patients with sarcoidosis. Atypical pulmonary findings have been uncommonly reported and include multiple large lung nodules, cavitation, lobar collapse, pleural effusions or pneumothorax. OBSERVATION: We report a 21-year-old non caucasian patient who presented with pulmonary nodular infiltration and sinonasal involvement revealing sarcoidosis. Thoracic and sinus computed tomographic scan showed both multiple excavated large lung nodules and micronodules, hilar lymphadenopathy and sinus thickening. Laboratory studies disclosed elevated angiotensin converting enzyme serum level (120UI/L). Outcome was favorable after institution of corticosteroids (at an initial dose of prednisone of 1mg/kg/day); at eight-month-follow-up, the patient was asymptomatic, while receiving prednisone 22.5mg/day. CONCLUSION: In patients exhibiting unusual pulmonary manifestations, diagnosis of sarcoidosis relies on compatible clinical signs, evidence of non-caseating granulomas, and exclusion of underlying conditions including infections, malignancy and other granulomatous diseases (Wegener disease, pneumoconiosis).


Asunto(s)
Seno Maxilar , Enfermedades de los Senos Paranasales/diagnóstico , Sarcoidosis Pulmonar/diagnóstico , Sarcoidosis/diagnóstico , Seno Esfenoidal , Antiinflamatorios/administración & dosificación , Antiinflamatorios/uso terapéutico , Diagnóstico Diferencial , Estudios de Seguimiento , Humanos , Masculino , Seno Maxilar/diagnóstico por imagen , Enfermedades de los Senos Paranasales/diagnóstico por imagen , Enfermedades de los Senos Paranasales/tratamiento farmacológico , Prednisona/administración & dosificación , Prednisona/uso terapéutico , Radiografía Torácica , Pruebas de Función Respiratoria , Sarcoidosis/diagnóstico por imagen , Sarcoidosis/tratamiento farmacológico , Sarcoidosis Pulmonar/diagnóstico por imagen , Sarcoidosis Pulmonar/tratamiento farmacológico , Seno Esfenoidal/diagnóstico por imagen , Factores de Tiempo , Tomografía Computarizada por Rayos X , Resultado del Tratamiento , Adulto Joven
19.
J Appl Microbiol ; 103(6): 2593-600, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18045443

RESUMEN

AIMS: We addressed the process of immigration of Bacillus thuringiensis from soil to leaves and its capacity to grow on bean diffusate medium (BDM), a medium designed to simulate the nutrient composition of the phylloplane. METHODS AND RESULTS: Two different B. thuringiensis strains were inoculated into soils, onto seeds or onto lower leaves of bean plants to determine if they were able to disperse to upper leaves under controlled conditions. While B. thuringiensis isolates were commonly recovered from leaves exposed to such inocula, populations were very low (<10 CFU cm(-2) of leaf). In addition, the number of cells of B. thuringiensis recovered decreased with increasing distance from the soil or from the inoculated leaves. Moreover, B. thuringiensis colonies did not grow well on BDM. CONCLUSIONS: This indicates that B. thuringiensis disperses poorly from the soil or the seed to the leaves or between leaves of the same plant under controlled conditions. Bacillus thuringiensis apparently has greater nutrient requirements than other bacterial species that are prominent inhabitants of the phylloplane. SIGNIFICANCE AND IMPACT OF THE STUDY: Finding the mechanisms that favour bacteria colonization on leaves will in turn help to improve the efficacy of biocontrol agents against the target pests.


Asunto(s)
Bacillus thuringiensis/fisiología , Fabaceae/microbiología , Control Biológico de Vectores , Hojas de la Planta/microbiología , Microbiología del Suelo , Técnicas Bacteriológicas , Ecosistema , Organismos Modificados Genéticamente
20.
J Appl Microbiol ; 102(1): 77-88, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17184322

RESUMEN

AIM: To evaluate the genetic and molecular diversity and insecticidal activity of Bacillus thuringiensis isolates from all the natural regions of Colombia. METHODS AND RESULTS: A total of 445 isolates from a collection of B. thuringiensis were characterized. The parasporal crystal morphology that was most abundant was bipyramidal (60%). Almost 10% of the isolates were toxic to Spodoptera frugiperda and 5.6% against Culex quinquefasciatus larvae. cry gene content determined by PCR indicated that 10.6% of the isolates contained cry1 genes and 1.1% contained cry2, cry4 or cry11 genes. Protein content of the parasporal crystal was determined by SDS-PAGE; 25 and 18 different protein profiles were found in isolates active against S. frugiperda and C. quinquefasciatus, respectively. CONCLUSIONS: Bacillus thuringiensis presents great genetic and molecular diversity even in isolates from the same soil sample. Moreover, the diversity and activity of the isolates might have a relationship with the geographical origin of the samples. SIGNIFICANCE AND IMPACT OF THE STUDY: The results obtained here indicate that some of the B. thuringiensis isolates characterized in this study are potential control agents that could be used in programmes against mosquitoes and S. frugiperda.


Asunto(s)
Bacillus thuringiensis/genética , Dípteros/microbiología , Lepidópteros/microbiología , Adenosina/análogos & derivados , Adenosina/biosíntesis , Animales , Proteínas Bacterianas/análisis , Toxinas Bacterianas/biosíntesis , Biodiversidad , Colombia , Criptocromos , Culex/microbiología , Electroforesis en Gel de Poliacrilamida/métodos , Flavoproteínas/genética , Genes Bacterianos/genética , Insecticidas , Larva/microbiología , Reacción en Cadena de la Polimerasa/métodos , Spodoptera/microbiología , Azúcares Ácidos
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