RESUMEN
BACKGROUND: Previous evidence indicates that adjuvant, short-course androgen deprivation therapy (ADT) improves metastasis-free survival when given with primary radiotherapy for intermediate-risk and high-risk localised prostate cancer. However, the value of ADT with postoperative radiotherapy after radical prostatectomy is unclear. METHODS: RADICALS-HD was an international randomised controlled trial to test the efficacy of ADT used in combination with postoperative radiotherapy for prostate cancer. Key eligibility criteria were indication for radiotherapy after radical prostatectomy for prostate cancer, prostate-specific antigen less than 5 ng/mL, absence of metastatic disease, and written consent. Participants were randomly assigned (1:1) to radiotherapy alone (no ADT) or radiotherapy with 6 months of ADT (short-course ADT), using monthly subcutaneous gonadotropin-releasing hormone analogue injections, daily oral bicalutamide monotherapy 150 mg, or monthly subcutaneous degarelix. Randomisation was done centrally through minimisation with a random element, stratified by Gleason score, positive margins, radiotherapy timing, planned radiotherapy schedule, and planned type of ADT, in a computerised system. The allocated treatment was not masked. The primary outcome measure was metastasis-free survival, defined as distant metastasis arising from prostate cancer or death from any cause. Standard survival analysis methods were used, accounting for randomisation stratification factors. The trial had 80% power with two-sided α of 5% to detect an absolute increase in 10-year metastasis-free survival from 80% to 86% (hazard ratio [HR] 0·67). Analyses followed the intention-to-treat principle. The trial is registered with the ISRCTN registry, ISRCTN40814031, and ClinicalTrials.gov, NCT00541047. FINDINGS: Between Nov 22, 2007, and June 29, 2015, 1480 patients (median age 66 years [IQR 61-69]) were randomly assigned to receive no ADT (n=737) or short-course ADT (n=743) in addition to postoperative radiotherapy at 121 centres in Canada, Denmark, Ireland, and the UK. With a median follow-up of 9·0 years (IQR 7·1-10·1), metastasis-free survival events were reported for 268 participants (142 in the no ADT group and 126 in the short-course ADT group; HR 0·886 [95% CI 0·688-1·140], p=0·35). 10-year metastasis-free survival was 79·2% (95% CI 75·4-82·5) in the no ADT group and 80·4% (76·6-83·6) in the short-course ADT group. Toxicity of grade 3 or higher was reported for 121 (17%) of 737 participants in the no ADT group and 100 (14%) of 743 in the short-course ADT group (p=0·15), with no treatment-related deaths. INTERPRETATION: Metastatic disease is uncommon following postoperative bed radiotherapy after radical prostatectomy. Adding 6 months of ADT to this radiotherapy did not improve metastasis-free survival compared with no ADT. These findings do not support the use of short-course ADT with postoperative radiotherapy in this patient population. FUNDING: Cancer Research UK, UK Research and Innovation (formerly Medical Research Council), and Canadian Cancer Society.
Asunto(s)
Antagonistas de Andrógenos , Anilidas , Nitrilos , Prostatectomía , Neoplasias de la Próstata , Compuestos de Tosilo , Humanos , Masculino , Neoplasias de la Próstata/patología , Neoplasias de la Próstata/radioterapia , Neoplasias de la Próstata/terapia , Neoplasias de la Próstata/tratamiento farmacológico , Antagonistas de Andrógenos/uso terapéutico , Antagonistas de Andrógenos/administración & dosificación , Anciano , Compuestos de Tosilo/uso terapéutico , Compuestos de Tosilo/administración & dosificación , Anilidas/uso terapéutico , Anilidas/administración & dosificación , Persona de Mediana Edad , Nitrilos/uso terapéutico , Nitrilos/administración & dosificación , Oligopéptidos/uso terapéutico , Oligopéptidos/administración & dosificación , Hormona Liberadora de Gonadotropina/agonistas , Terapia Combinada , Antígeno Prostático Específico/sangreRESUMEN
BACKGROUND: Androgen suppression is a central component of prostate cancer management but causes substantial long-term toxicity. Transdermal administration of oestradiol (tE2) circumvents first-pass hepatic metabolism and, therefore, should avoid the cardiovascular toxicity seen with oral oestrogen and the oestrogen-depletion effects seen with luteinising hormone releasing hormone agonists (LHRHa). We present long-term cardiovascular follow-up data from the Prostate Adenocarcinoma Transcutaneous Hormone (PATCH) trial programme. METHODS: PATCH is a seamless phase 2/3, randomised, multicentre trial programme at 52 study sites in the UK. Men with locally advanced or metastatic prostate cancer were randomly allocated (1:2 from August, 2007 then 1:1 from February, 2011) to either LHRHa according to local practice or tE2 patches (four 100 µg patches per 24 h, changed twice weekly, reducing to three patches twice weekly if castrate at 4 weeks [defined as testosterone ≤1·7 nmol/L]). Randomisation was done using a computer-based minimisation algorithm and was stratified by several factors, including disease stage, age, smoking status, and family history of cardiac disease. The primary outcome of this analysis was cardiovascular morbidity and mortality. Cardiovascular events, including heart failure, acute coronary syndrome, thromboembolic stroke, and other thromboembolic events, were confirmed using predefined criteria and source data. Sudden or unexpected deaths were attributed to a cardiovascular category if a confirmatory post-mortem report was available and as other relevant events if no post-mortem report was available. PATCH is registered with the ISRCTN registry, ISRCTN70406718; the study is ongoing and adaptive. FINDINGS: Between Aug 14, 2007, and July 30, 2019, 1694 men were randomly allocated either LHRHa (n=790) or tE2 patches (n=904). Overall, median follow-up was 3·9 (IQR 2·4-7·0) years. Respective castration rates at 1 month and 3 months were 65% and 93% among patients assigned LHRHa and 83% and 93% among those allocated tE2. 157 events from 145 men met predefined cardiovascular criteria, with a further ten sudden deaths with no post-mortem report (total 167 events in 153 men). 26 (2%) of 1694 patients had fatal cardiovascular events, 15 (2%) of 790 assigned LHRHa and 11 (1%) of 904 allocated tE2. The time to first cardiovascular event did not differ between treatments (hazard ratio 1·11, 95% CI 0·80-1·53; p=0·54 [including sudden deaths without post-mortem report]; 1·20, 0·86-1·68; p=0·29 [confirmed group only]). 30 (34%) of 89 cardiovascular events in patients assigned tE2 occurred more than 3 months after tE2 was stopped or changed to LHRHa. The most frequent adverse events were gynaecomastia (all grades), with 279 (38%) events in 730 patients who received LHRHa versus 690 (86%) in 807 patients who received tE2 (p<0·0001) and hot flushes (all grades) in 628 (86%) of those who received LHRHa versus 280 (35%) who received tE2 (p<0·0001). INTERPRETATION: Long-term data comparing tE2 patches with LHRHa show no evidence of a difference between treatments in cardiovascular mortality or morbidity. Oestrogens administered transdermally should be reconsidered for androgen suppression in the management of prostate cancer. FUNDING: Cancer Research UK, and Medical Research Council Clinical Trials Unit at University College London.
Asunto(s)
Síndrome Coronario Agudo/epidemiología , Adenocarcinoma/tratamiento farmacológico , Antagonistas de Andrógenos/administración & dosificación , Estradiol/administración & dosificación , Estrógenos/administración & dosificación , Insuficiencia Cardíaca/epidemiología , Accidente Cerebrovascular Isquémico/epidemiología , Neoplasias de la Próstata/tratamiento farmacológico , Síndrome Coronario Agudo/mortalidad , Adenocarcinoma/patología , Anciano , Anciano de 80 o más Años , Accidente Cerebrovascular Embólico/epidemiología , Accidente Cerebrovascular Embólico/mortalidad , Hormona Liberadora de Gonadotropina/agonistas , Ginecomastia/inducido químicamente , Insuficiencia Cardíaca/mortalidad , Humanos , Accidente Cerebrovascular Isquémico/mortalidad , Masculino , Persona de Mediana Edad , Neoplasias de la Próstata/patología , Accidente Cerebrovascular Trombótico/epidemiología , Accidente Cerebrovascular Trombótico/mortalidad , Parche Transdérmico , Reino UnidoRESUMEN
BACKGROUND: It is unclear whether adjuvant or early salvage radiotherapy following radical prostatectomy is more appropriate for men who present with localised or locally advanced prostate cancer. We aimed to prospectively plan a systematic review of randomised controlled trials (RCTs) comparing these radiotherapy approaches. METHODS: We used a prospective framework for adaptive meta-analysis (FAME), starting the review process while eligible trials were ongoing. RCTs were eligible if they aimed to compare immediate adjuvant radiotherapy versus early salvage radiotherapy, following radical prostatectomy in men (age ≥18 years) with intermediate-risk or high-risk, localised or locally advanced prostate cancer. We searched trial registers and conference proceedings until July 8, 2020, to identify eligible RCTs. By establishing the ARTISTIC collaboration with relevant trialists, we were able to anticipate when eligible trial results would emerge, and we developed and registered a protocol with PROSPERO before knowledge of the trial results (CRD42019132669). We used a harmonised definition of event-free survival, as the time from randomisation until the first evidence of either biochemical progression (prostate-specific antigen [PSA] ≥0·4 ng/mL and rising after completion of any postoperative radiotherapy), clinical or radiological progression, initiation of a non-trial treatment, death from prostate cancer, or a PSA level of at least 2·0 ng/mL at any time after randomisation. We predicted when we would have sufficient power to assess whether adjuvant radiotherapy was superior to early salvage radiotherapy. Investigators supplied results for event-free survival, both overall and within predefined patient subgroups. Hazard ratios (HRs) for the effects of radiotherapy timing on event-free survival and subgroup interactions were combined using fixed-effect meta-analysis. FINDINGS: We identified three eligible trials and were able to obtain updated results for event-free survival for 2153 patients recruited between November, 2007, and December, 2016. Median follow-up ranged from 60 months to 78 months, with a maximum follow-up of 132 months. 1075 patients were randomly assigned to receive adjuvant radiotherapy and 1078 to a policy of early salvage radiotherapy, of whom 421 (39·1%) had commenced treatment at the time of analysis. Patient characteristics were balanced within trials and overall. Median age was similar between trials at 64 or 65 years (with IQRs ranging from 59 to 68 years) across the three trials and most patients (1671 [77·6%]) had a Gleason score of 7. All trials were assessed as having low risk of bias. Based on 270 events, the meta-analysis showed no evidence that event-free survival was improved with adjuvant radiotherapy compared with early salvage radiotherapy (HR 0·95, 95% CI 0·75-1·21; p=0·70), with only a 1 percentage point (95% CI -2 to 3) change in 5-year event-free survival (89% vs 88%). Results were consistent across trials (heterogeneity p=0·18; I2=42%). INTERPRETATION: This collaborative and prospectively designed systematic review and meta-analysis suggests that adjuvant radiotherapy does not improve event-free survival in men with localised or locally advanced prostate cancer. Until data on long-term outcomes are available, early salvage treatment would seem the preferable treatment policy as it offers the opportunity to spare many men radiotherapy and its associated side-effects. FUNDING: UK Medical Research Council.
Asunto(s)
Prostatectomía , Neoplasias de la Próstata/radioterapia , Neoplasias de la Próstata/cirugía , Biomarcadores de Tumor/sangre , Supervivencia sin Enfermedad , Humanos , Masculino , Clasificación del Tumor , Estudios Prospectivos , Antígeno Prostático Específico/sangre , Neoplasias de la Próstata/patología , Radioterapia Adyuvante , Ensayos Clínicos Controlados Aleatorios como Asunto , Terapia RecuperativaRESUMEN
There have been no paediatric randomised trials describing the effect of planned treatment interruptions (PTIs) of antiretroviral therapy (ART) on adherence, or evaluating acceptability of such a strategy. In PENTA 11, HIV-infected children were randomised to CD4-guided PTIs (n = 53) or continuous therapy (CT, n = 56). Carers, and children if appropriate, completed questionnaires on adherence to ART and acceptability of PTIs. There was no difference in reported adherence on ART between CT and PTI groups; non-adherence (reporting missed doses over the last 3 days or marking <100 % adherence since the last clinical visit on a visual analogue scale) was 18 % (20/111) and 14 % (12/83) on carer questionnaires in the CT and PTI groups respectively (odds ratios, OR (95 % CI) = 1.04 (0.20, 5.41), χ(2) (1) = 0.003, p = 0.96). Carers in Europe/USA reported non-adherence more often (31/121, 26 %) than in Thailand (1/73, 1 %; OR (95 % CI) = 54.65 (3.68, 810.55), χ(2) (1) = 8.45, p = 0.004). The majority of families indicated they were happy to have further PTIs (carer: 23/36, 64 %; children: 8/13, 62 %), however many reported more clinic visits during PTI were a problem (carer: 15/36, 42 %; children: 6/12, 50 %).
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Antirretrovirales/administración & dosificación , Terapia Antirretroviral Altamente Activa/métodos , Infecciones por VIH/tratamiento farmacológico , Cumplimiento de la Medicación , Aceptación de la Atención de Salud , Adolescente , Recuento de Linfocito CD4 , Cuidadores/psicología , Niño , Preescolar , Esquema de Medicación , Europa (Continente) , Femenino , Estudios de Seguimiento , Infecciones por VIH/virología , VIH-1 , Humanos , Masculino , Encuestas y Cuestionarios , Tailandia , Estados Unidos , Carga ViralRESUMEN
The outcome of bacterial infection in plants is determined by the ability of the pathogen to successfully occupy the apoplastic space and deliver a constellation of effectors that collectively suppress basal and effector-triggered immune responses. In this study, we examined the metabolic changes associated with establishment of disease using analytical techniques that interrogated a range of chemistries. We demonstrated clear differences in the metabolome of Arabidopsis thaliana leaves infected with virulent Pseudomonas syringae within 8 h of infection. In addition to confirmation of changes in phenolic and indolic compounds, we identified rapid alterations in the abundance of amino acids and other nitrogenous compounds, specific classes of glucosinolates, disaccharides, and molecules that influence the prevalence of reactive oxygen species. Our data illustrate that, superimposed on defence suppression, pathogens reconfigure host metabolism to provide the sustenance required to support exponentially growing populations of apoplastically localized bacteria. We performed a detailed baseline study reporting the metabolic dynamics associated with bacterial infection. Moreover, we have integrated these data with the results of transcriptome profiling to distinguish metabolomic pathways that are transcriptionally activated from those that are post-transcriptionally regulated.
Asunto(s)
Arabidopsis/metabolismo , Pseudomonas syringae/patogenicidad , Arabidopsis/genética , Arabidopsis/microbiología , Cromatografía de Gases y Espectrometría de Masas , Espectroscopía de Resonancia Magnética , Metabolómica , Hojas de la Planta/microbiología , TranscriptomaRESUMEN
PENTA Guidelines aim to provide practical recommendations for treating children with HIV infection in Europe. Changes to guidance since 2004 have been informed by new evidence and by expectations of better outcomes following the ongoing success of antiretroviral therapy (ART). Participation in PENTA trials of simplifying treatment is encouraged. The main changes are in the following sections: 'When to start ART': Treatment is recommended for all infants, and at higher CD4 cell counts and percentages in older children, in line with changes to adult guidelines. The number of age bands has been reduced to simplify and harmonize with other paediatric guidelines. Greater emphasis is placed on CD4 cell count in children over 5 years, and guidance is provided where CD4% and CD4 criteria differ. 'What to start with': A three-drug regimen of two nucleoside reverse transcriptase inhibitors (NRTIs) with either a nonnucleoside reverse transcriptase inhibitor (NNRTI) or a boosted protease inhibitor (PI) remains the first choice combination. Lamivudine and abacavir are the NRTI backbone of choice for most children, based on long-term follow-up in the PENTA 5 trial. Stavudine is no longer recommended. Whether to start with an NNRTI or PI remains unclear, but PENPACT 1 trial results in 2009 may help to inform this. All PIs should be ritonavir boosted. Recommendations on use of resistance testing, therapeutic drug monitoring and HLA testing draw from data in adults and from European paediatric cohort studies. Recently updated US and WHO paediatric guidelines provide more detailed review of the evidence base. Differences between guidelines are highlighted and explained.
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Antirretrovirales/uso terapéutico , Terapia Antirretroviral Altamente Activa/métodos , Infecciones por VIH/tratamiento farmacológico , VIH-1 , Adolescente , Adulto , Factores de Edad , Antiinfecciosos/uso terapéutico , Niño , Preescolar , Farmacorresistencia Viral , Europa (Continente) , Femenino , Infecciones por VIH/diagnóstico , Infecciones por VIH/transmisión , Sobrevivientes de VIH a Largo Plazo , Hepatitis Viral Humana/complicaciones , Hepatitis Viral Humana/tratamiento farmacológico , Humanos , Lactante , Recién Nacido , Transmisión Vertical de Enfermedad Infecciosa , Educación del Paciente como Asunto , Neumonía por Pneumocystis/prevención & control , Embarazo , ARN Viral/sangre , Ensayos Clínicos Controlados Aleatorios como Asunto , Insuficiencia del Tratamiento , Combinación Trimetoprim y Sulfametoxazol/uso terapéutico , Tuberculosis/complicaciones , Tuberculosis/tratamiento farmacológico , Adulto JovenRESUMEN
A mutant of aristolochene synthase, in which Phe 178 was replaced by Val, produced significant amounts of alpha-and beta-farnesene as well as alpha and beta-selinene and selina-4,11-diene, suggesting that Phe 178 is involved in the stabilisation of transition states preceding germacrene A and following eudesmane cation.
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Isomerasas/química , Fenilalanina/química , Fosfatos de Poliisoprenilo/química , Sesquiterpenos de Germacrano/química , Sustitución de Aminoácidos , Catálisis , Ciclización , Isomerasas/genética , Mutagénesis Sitio-Dirigida , SesquiterpenosRESUMEN
Analysis of the hydrocarbons produced during catalysis by mutants of aristolochene synthase from Penicillium roqueforti indicated that Trp 334 had a pivotal function for the efficient production of aristolochene from farnesylpyrophosphate most likely by stabilising the intermediate, eudesmane cation.
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Isomerasas/metabolismo , Sesquiterpenos de Eudesmano , Sesquiterpenos/química , Triptófano/química , Catálisis , Cationes , Penicillium/enzimología , Penicillium/genética , Fosfatos de Poliisoprenilo/químicaRESUMEN
BACKGROUND: Lopinavir/ritonavir (LPV/r) pediatric tablets (100/25 mg) are approved by the United States Food and Drug Administration (FDA) and European Medicines Agency (EMA) as part of combination antiretroviral therapy. Dosing is based on body weight bands or body surface area under FDA approval and only body surface area by the EMA. This can lead to a different recommended dose. In addition, weight band-based dosing has not been formally studied in the target population. We evaluated the pharmacokinetics (PK) of LPV/r in children, administered twice daily according to the FDA weight bands, using pediatric tablets. METHODS: Fifty-three HIV-infected children were included in the PK substudy of the Paediatric European Network for the Treatment of AIDS 18 trial (KONCERT). In this study, children were randomized to receive LPV/r twice or once daily, according to FDA weight bands. A PK assessment was performed in 17, 16 and 20 children in the 15-25 kg, ≥ 25-35 kg and >35 kg weight band, respectively, while children took the tablets twice daily. Rich sampling was performed, and PK parameters were calculated by noncompartmental analysis. Given the high percentage of Asian children, it was also tested whether there was a difference in PK parameters between Asian and non-Asian children. RESULTS: For the total group, LPV geometric mean AUC0-12, Cmax and C12 were 106.9 h × mg/L, 12.0 mg/L and 4.9 mg/L, respectively. There were no significant differences in LPV PK parameters between the weight bands. In addition, weight was not found to be associated with variability in Cmax, C12 or AUC0-12 for the LPV PK parameters. CONCLUSIONS: FDA weight band-based dosing recommendations provide adequate exposure to LPV when using LPV/r pediatric tablets.
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Infecciones por VIH/tratamiento farmacológico , Inhibidores de la Proteasa del VIH/farmacocinética , Lopinavir/farmacocinética , Ritonavir/farmacocinética , Adolescente , Análisis de Varianza , Peso Corporal , Niño , Quimioterapia Combinada , Femenino , Infecciones por VIH/epidemiología , Inhibidores de la Proteasa del VIH/administración & dosificación , Inhibidores de la Proteasa del VIH/sangre , Inhibidores de la Proteasa del VIH/uso terapéutico , Humanos , Lopinavir/administración & dosificación , Lopinavir/sangre , Lopinavir/uso terapéutico , Masculino , Ritonavir/administración & dosificación , Ritonavir/sangre , Ritonavir/uso terapéutico , ComprimidosRESUMEN
BACKGROUND: We aimed to establish levels of consumer involvement in randomised controlled trials (RCTs), meta-analyses and other studies carried out by the UK Medical Research Council (MRC) Clinical Trials Unit across the range of research programs, predominantly in cancer and HIV. METHODS: Staff responsible for studies that were included in a Unit Progress Report (MRC CTU, April 2009) were asked to complete a semi-structured questionnaire survey regarding consumer involvement. This was defined as active involvement of consumers as partners in the research process and not as subjects of that research. The electronic questionnaires combined open and closed questions, intended to capture quantitative and qualitative information on whether studies had involved consumers; types of activities undertaken; recruitment and support; advantages and disadvantages of involvement and its perceived impact on aspects of the research. RESULTS: Between October 2009 and April 2010, 138 completed questionnaires (86%) were returned. Studies had been conducted over a 20 year period from 1989, and around half were in cancer; 30% in HIV and 20% were in other disease areas including arthritis, tuberculosis and blood transfusion medicine. Forty-three studies (31%) had some consumer involvement, most commonly as members of trial management groups (TMG) [88%]. A number of positive impacts on both the research and the researcher were identified. Researchers generally felt involvement was worthwhile and some felt that consumer involvement had improved the credibility of the research. Benefits in design and quality, trial recruitment, dissemination and decision making were also perceived. Researchers felt they learned from consumer involvement, albeit that there were some barriers. CONCLUSIONS: Whilst most researchers identified benefits of involving consumers, most of studies included in the survey had no involvement. Information from this survey will inform the development of a unit policy on consumer involvement, to guide future research conducted within the MRC Clinical Trials Unit and beyond.
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Investigación Biomédica/organización & administración , Participación de la Comunidad , Relaciones Comunidad-Institución , Metaanálisis como Asunto , Ensayos Clínicos Controlados Aleatorios como Asunto/métodos , Proyectos de Investigación , Investigación Biomédica/normas , Relaciones Comunidad-Institución/normas , Conducta Cooperativa , Guías como Asunto , Humanos , Percepción , Ensayos Clínicos Controlados Aleatorios como Asunto/normas , Proyectos de Investigación/normas , Encuestas y Cuestionarios , Reino UnidoRESUMEN
Changes occurring to plant cell walls were examined following inoculation of Arabidopsis leaves with pathogenic and non-pathogenic (hrpA mutant) strains of Pseudomonas syringae pv. tomato. We have targeted low molecular weight, cross-linked phenolic and indolic compounds that were released from wall preparations by alkaline hydrolysis at 70 degrees C and in a microwave bomb. Significantly higher concentrations of syringaldehyde, p hydroxybenzaldehyde and indole carboxylic acid were recovered from cell walls isolated from leaves 24h after challenge with the hrpA mutant compared with wild-type DC3000. Time course experiments showed that the accumulation of indole carboxylic acid and the other group of differentiating metabolites had occurred within 12h of inoculation. The callose synthase deficient mutant pmr4-1 was more resistant than wild-type Columbia plants to P. syringae pv. tomato. Restricted bacterial multiplication was associated with increased accumulation of indole carboxylic acid on the plant cell wall. In the absence of callose deposition in the pmr 4-1 mutant, indolic derivatives may serve as a structural scaffold for wall modifications following bacterial challenge.
Asunto(s)
Arabidopsis , Ácidos Carboxílicos/metabolismo , Pared Celular/metabolismo , Indoles/metabolismo , Enfermedades de las Plantas/microbiología , Pseudomonas syringae/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/microbiología , Benzaldehídos/análisis , Hojas de la Planta/metabolismo , Pseudomonas syringae/genética , Factores de TiempoRESUMEN
BACKGROUND: Agrobacterium tumefaciens strain GV3101 (pMP90) is widely used in transient gene expression assays, including assays to study pathogen effectors and plant disease resistance mechanisms. However, inoculation of A. tumefaciens GV3101 into Nicotiana tabacum (tobacco) leaves prior to infiltration with pathogenic and non-host strains of Pseudomonas syringae results in suppression of macroscopic symptoms when compared with leaves pre-treated with a buffer control. METHODOLOGY/FINDINGS: To gain further insight into the mechanistic basis of symptom suppression by A. tumefaciens we examined the effect of pre-treatment with A. tumefaciens on the growth of P. syringae, the production of the plant signalling molecules salicylic acid (SA) and abscisic acid (ABA), and the presence of callose deposits. Pre-treatment with A. tumefaciens reduced ABA levels, P. syringae multiplication and P. syringae-elicited SA and ABA production, but promoted increased callose deposition. However, pre-treatment with A. tumefaciens did not suppress necrosis or SA production in leaves inoculated with the elicitor HrpZ. CONCLUSIONS/SIGNIFICANCE: Collectively, these results show that inoculation of N. tabacum leaves with A. tumefaciens alters plant hormone levels and plant defence responses to P. syringae, and demonstrate that researchers should consider the impact of A. tumefaciens on plant signal transduction when using A. tumefaciens-mediated transient expression assays to investigate ABA-regulated processes or pathogenicity and plant defence mechanisms.
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Ácido Abscísico/metabolismo , Nicotiana/metabolismo , Pseudomonas syringae/metabolismo , Ácido Salicílico/metabolismo , Nicotiana/microbiologíaRESUMEN
We describe an efficient method for the rapid quantitative determination of the abundance of three acidic plant hormones from a single crude extract directly by LC/MS/MS. The method exploits the sensitivity of MS and uses multiple reaction monitoring and isotopically labelled samples to quantify the phytohormones abscisic acid, jasmonic acid and salicylic acid in Arabidopsis leaf tissue.
RESUMEN
The mechanistic details of the cyclisation of farnesylpyrophosphate (FPP) by aristolochene synthase (AS) from Penicillium roqueforti have only recently begun to emerge, mainly through the analysis of the reaction products generated by AS-mutants. The reaction proceeds through several intermediates including germacrene A and eudesmane cation. Previous work suggested that the side chain of phenylalanine 178 promoted the conversion of eudesmane cation to aristolochene. We now report that the catalytic function of this residue during the conversion of eudesmane cation to aristolochene is mainly due to the large size of its side chain, which facilitates the hydride shift from C2 to C3, rather than its aromatic character. In addition, F178 appears to control the regioselectivity of the final deprotonation step and, together with F112, helps stabilise the developing positive charge on C1 after the expulsion of pyrophosphate from the substrate. These results complete a screen of likely active-site aromatic residues and establish their respective roles in the conversion of FPP to aristolochene.