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result(s) for
"Barbier, Francois"
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Bloodstream infections in critically ill patients: an expert statement
by
Timsit Jean-François
,
Bassetti Matteo
,
Ruppé Etienne
in
Antibiotics
,
Antiinfectives and antibacterials
,
Antimicrobial agents
2020
Bloodstream infection (BSI) is defined by positive blood cultures in a patient with systemic signs of infection and may be either secondary to a documented source or primary—that is, without identified origin. Community-acquired BSIs in immunocompetent adults usually involve drug-susceptible bacteria, while healthcare-associated BSIs are frequently due to multidrug-resistant (MDR) strains. Early adequate antimicrobial therapy is a key to improve patient outcomes, especially in those with criteria for sepsis or septic shock, and should be based on guidelines and direct examination of available samples. Local epidemiology, suspected source, immune status, previous antimicrobial exposure, and documented colonization with MDR bacteria must be considered for the choice of first-line antimicrobials in healthcare-associated and hospital-acquired BSIs. Early genotypic or phenotypic tests are now available for bacterial identification and early detection of resistance mechanisms and may help, though their clinical impact warrants further investigations. Initial antimicrobial dosing should take into account the pharmacokinetic alterations commonly observed in ICU patients, with a loading dose in case of sepsis or septic shock. Initial antimicrobial combination attempting to increase the antimicrobial spectrum should be discussed when MDR bacteria are suspected and/or in the most severely ill patients. Source identification and control should be performed as soon as the hemodynamic status is stabilized. De-escalation from a broad-spectrum to a narrow-spectrum antimicrobial may reduce antibiotic selection pressure without negative impact on mortality. The duration of therapy is usually 5–8 days though longer durations may be discussed depending on the underlying illness and the source of infection. This narrative review covers the epidemiology, diagnostic workflow and therapeutic aspects of BSI in ICU patients and proposed up-to-date expert statements.
Journal Article
HEXOKINASE1 signalling promotes shoot branching and interacts with cytokinin and strigolactone pathways
by
Beveridge, Christine
,
Fichtner, Franziska
,
Weiste, Christoph
in
Agricultural sciences
,
apical dominance
,
auxin
2021
Plant architecture is controlled by several endogenous signals including hormones and sugars. However, only little information is known about the nature and roles of the sugar signalling pathways in this process. Here we test whether the sugar signalling pathway mediated by HEXOKINASE1 (HXK1) is involved in the control of shoot branching. To test the involvement of HXK1 in shoot branching and in the hormonal network controlling this process, we modulated the HXK1 pathway using physiological and genetic approaches in rose, pea and arabidopsis. Mannose-induced HXK signalling triggered bud outgrowth in rose and pea. In arabidopsis, both HXK1 deficiency and defoliation led to decreased shoot branching and conferred hypersensitivity to auxin. Complementation of the HXK1 knockout mutant gin2 with a catalytically inactive HXK1, restored shoot branching to the wild-type level. HXK1-deficient plants displayed decreased cytokinin levels and increased expression of MAX2, which is required for strigolactone signalling. The branching phenotype of HXK1-deficient plants could be partly restored by cytokinin treatment and strigolactone deficiency could override the negative impact of HXK1 deficiency on shoot branching. Our observations demonstrate that HXK1 signalling contributes to the regulation of shoot branching and interacts with hormones to modulate plant architecture.
Journal Article
Sucrose promotes D53 accumulation and tillering in rice
by
Beveridge, Christine
,
Sun, Yinglu
,
Fichtner, Franziska
in
Arabidopsis - genetics
,
Branching
,
Degradation
2022
Shoot branching is regulated by multiple signals. Previous studies have indicated that sucrose may promote shoot branching through suppressing the inhibitory effect of the hormone strigolactone (SL). However, the molecular mechanisms underlying this effect are unknown. Here, we used molecular and genetic tools to identify the molecular targets underlying the antagonistic interaction between sucrose and SL. We showed that sucrose antagonizes the suppressive action of SL on tillering in rice and on the degradation of D53, a major target of SL signalling. Sucrose inhibits the gene expression of D3, the orthologue of the Arabidopsis F-box MAX2 required for SL signalling. Overexpression of D3 antagonizes sucrose inhibition of D53 degradation and enables the SL inhibition of tillering under high sucrose. Sucrose prevents SL-induced degradation of D14, the SL receptor involved in D53 degradation. In contrast to D3, D14 overexpression enhances D53 protein levels and sucrose-induced tillering, even in the presence of SL. Our results show that sucrose inhibits SL response by affecting key components of SL signalling and, together with previous studies reporting the inhibition of SL synthesis by nitrate and phosphate, demonstrate the central role played by SLs in the regulation of plant architecture by nutrients.
Journal Article
Regulation of shoot branching in arabidopsis by trehalose 6-phosphate
by
Beveridge, Christine A.
,
Lunn, John E.
,
Fichtner, Franziska
in
Arabidopsis - genetics
,
Arabidopsis thaliana
,
Arabidopsis thaliana (arabidopsis)
2021
• Trehalose 6-phosphate (Tre6P) is a sucrose signalling metabolite that has been implicated in regulation of shoot branching, but its precise role is not understood.
• We expressed tagged forms of TREHALOSE-6-PHOSPHATE SYNTHASE1 (TPS1) to determine where Tre6P is synthesized in arabidopsis (Arabidopsis thaliana), and investigated the impact of localized changes in Tre6P levels, in axillary buds or vascular tissues, on shoot branching in wild-type and branching mutant backgrounds.
• TPS1 is expressed in axillary buds and the subtending vasculature, as well as in the leaf and stem vasculature. Expression of a heterologous Tre6P phosphatase (TPP) to lower Tre6P in axillary buds strongly delayed bud outgrowth in long days and inhibited branching in short days. TPP expression in the vasculature also delayed lateral bud outgrowth and decreased branching. Increased Tre6P in the vasculature enhanced branching and was accompanied by higher expression of FLOWERING LOCUS T (FT) and upregulation of sucrose transporters. Increased vascular Tre6P levels enhanced branching in branched1 but not in ft mutant backgrounds.
• These results provide direct genetic evidence of a local role for Tre6P in regulation of axillary bud outgrowth within the buds themselves, and also connect Tre6P with systemic regulation of shoot branching via FT.
Journal Article
Rationalizing antimicrobial therapy in the ICU: a narrative review
by
Taccone, Fabio Silvio
,
Salluh, Jorge
,
Kipnis, Eric
in
Anesthesiology
,
Anti-Infective Agents - adverse effects
,
Anti-Infective Agents - therapeutic use
2019
The massive consumption of antibiotics in the ICU is responsible for substantial ecological side effects that promote the dissemination of multidrug-resistant bacteria (MDRB) in this environment. Strikingly, up to half of ICU patients receiving empirical antibiotic therapy have no definitively confirmed infection, while de-escalation and shortened treatment duration are insufficiently considered in those with documented sepsis, highlighting the potential benefit of implementing antibiotic stewardship programs (ASP) and other quality improvement initiatives. The objective of this narrative review is to summarize the available evidence, emerging options, and unsolved controversies for the optimization of antibiotic therapy in the ICU. Published data notably support the need for better identification of patients at risk of MDRB infection, more accurate diagnostic tools enabling a rule-in/rule-out approach for bacterial sepsis, an individualized reasoning for the selection of single-drug or combination empirical regimen, the use of adequate dosing and administration schemes to ensure the attainment of pharmacokinetics/pharmacodynamics targets, concomitant source control when appropriate, and a systematic reappraisal of initial therapy in an attempt to minimize collateral damage on commensal ecosystems through de-escalation and treatment-shortening whenever conceivable. This narrative review also aims at compiling arguments for the elaboration of actionable ASP in the ICU, including improved patient outcomes and a reduction in antibiotic-related selection pressure that may help to control the dissemination of MDRB in this healthcare setting.
Journal Article
Potentially modifiable factors contributing to sepsis-associated encephalopathy
by
Darmon, Michael
,
Jamali, Samir
,
Mariotte, Eric
in
Acute Kidney Injury - epidemiology
,
Aged
,
Anesthesiology
2017
Purpose
Identifying modifiable factors for sepsis-associated encephalopathy may help improve patient care and outcomes.
Methods
We conducted a retrospective analysis of a prospective multicenter database. Sepsis-associated encephalopathy (SAE) was defined by a score on the Glasgow coma scale (GCS) <15 or when features of delirium were noted. Potentially modifiable risk factors for SAE at ICU admission and its impact on mortality were investigated using multivariate logistic regression analysis and Cox proportional hazard modeling, respectively.
Results
We included 2513 patients with sepsis at ICU admission, of whom 1341 (53%) had sepsis-associated encephalopathy. After adjusting for baseline characteristics, site of infection, and type of admission, the following factors remained independently associated with sepsis-associated encephalopathy: acute renal failure [adjusted odds ratio (aOR) = 1.41, 95% confidence interval (CI) 1.19–1.67], hypoglycemia <3 mmol/l (aOR = 2.66, 95% CI 1.27–5.59), hyperglycemia >10 mmol/l (aOR = 1.37, 95% CI 1.09–1.72), hypercapnia >45 mmHg (aOR = 1.91, 95% CI 1.53–2.38), hypernatremia >145 mmol/l (aOR = 2.30, 95% CI 1.48–3.57), and
S. aureus
(aOR = 1.54, 95% CI 1.05–2.25). Sepsis-associated encephalopathy was associated with higher mortality, higher use of ICU resources, and longer hospital stay. After adjusting for age, comorbidities, year of admission, and non-neurological SOFA score, even mild alteration of mental status (i.e., a score on the GCS of 13–14) remained independently associated with mortality (adjusted hazard ratio = 1.38, 95% CI 1.09–1.76).
Conclusions
Acute renal failure and common metabolic disturbances represent potentially modifiable factors contributing to sepsis-associated encephalopathy. However, a true causal relationship has yet to be demonstrated. Our study confirms the prognostic significance of mild alteration of mental status in patients with sepsis.
Journal Article
A phenol/chloroform-free method to extract nucleic acids from recalcitrant, woody tropical species for gene expression and sequencing
by
Beveridge, Christine A.
,
Chabikwa, Tinashe G.
,
Powell, Rosanna
in
Avocado
,
avocados
,
Biochemistry
2019
Background
Woody tropical plants contain high levels of complex organic compounds that inhibit the chemical procedures needed to extract RNA or DNA, thus compromising downstream applications such as RNA sequencing and analysis of gene expression. To overcome this issue, researchers must use extraction protocols using CTAB/PVP buffer instead of commercially available DNA/RNA extraction kits. However, these protocols are time-consuming, use toxic chemicals like phenol and chloroform, and can only be used to process a small number of samples at a time. To overcome these issues, we developed a new CTAB/PVP based protocol for RNA or DNA extraction that eliminates the traditional phenol/chloroform step. Furthermore, the protocol was developed for 96-well plates to speed up processing.
Results
Our new protocol enabled us to successfully extract RNA from macadamia, avocado, and mango tissues that are traditionally difficult to work with. This RNA was then successfully used to synthesise cDNA for real-time quantitative PCR and to generate good quality RNA-Seq libraries. Our protocol can be easily converted for rapid DNA extraction from different tropical and sub-tropical tree species.
Conclusion
This method enables safer and faster DNA and RNA extraction from recalcitrant species, thus facilitating future work on tropical trees.
Journal Article
Sugar availability suppresses the auxin-induced strigolactone pathway to promote bud outgrowth
2020
• Apical dominance occurs when the growing shoot tip inhibits the outgrowth of axillary buds. Apically-derived auxin in the nodal stem indirectly inhibits bud outgrowth via cytokinins and strigolactones. Recently, sugar deprivation was found to contribute to this phenomenon.
• Using rose and pea, we investigated whether sugar availability interacts with auxin in bud outgrowth control, and the role of cytokinins and strigolactones, in vitro and in planta.
• We show that sucrose antagonises auxin’s effect on bud outgrowth, in a dose-dependent and coupled manner. Sucrose also suppresses strigolactone inhibition of outgrowth and the rms3 strigolactone-perception mutant is less affected by reducing sucrose supply. However, sucrose does not interfere with the regulation of cytokinin levels by auxin and stimulates outgrowth even with optimal cytokinin supply. These observations were assembled into a computational model in which sucrose represses bud response to strigolactones, largely independently of cytokinin levels. It quantitatively captures our observed dose-dependent sucrose-hormones effects on bud outgrowth and allows us to express outgrowth response to various combinations of auxin and sucrose levels as a simple quantitative law.
• This study places sugars in the bud outgrowth regulatory network and paves the way for a better understanding of branching plasticity in response to environmental and genotypic factors.
Journal Article
Sucrose is an early modulator of the key hormonal mechanisms controlling bud outgrowth in Rosa hybrida
by
Écologie et biologie des interactions (EBI)
,
Barrière, Quentin
,
Leduc, Nathalie
in
Biological Transport
,
Botanics
,
Cytokinins - metabolism
2015
Sugar has only recently been identified as a key player in triggering bud outgrowth, while hormonal control of bud outgrowth is already well established. To get a better understanding of sugar control, the present study investigated how sugar availability modulates the hormonal network during bud outgrowth in Rosa hybrida. Other plant models, for which mutants are available, were used when necessary. Buds were grown in vitro to manipulate available sugars. The temporal patterns of the hormonal regulatory network were assessed in parallel with bud outgrowth dynamics. Sucrose determined bud entrance into sustained growth in a concentration-dependent manner. Sustained growth was accompanied by sustained auxin production in buds, and sustained auxin export in a DR5::GUS-expressing pea line. Several events occurred ahead of sucrose-stimulated bud outgrowth. Sucrose upregulated early auxin synthesis genes (RhTAR1, RhYUC1) and the auxin efflux carrier gene RhPIN1, and promoted PIN1 abundance at the plasma membrane in a pPIN1::PIN1-GFP-expressing tomato line. Sucrose downregulated both RwMAX2, involved in the strigolactone-transduction pathway, and RhBRC1, a repressor of branching, at an early stage. The presence of sucrose also increased stem cytokinin content, but sucrose-promoted bud outgrowth was not related to that pathway. In these processes, several non-metabolizable sucrose analogues induced sustained bud outgrowth in R. hybrida, Pisum sativum, and Arabidopsis thaliana, suggesting that sucrose was involved in a signalling pathway. In conclusion, we identified potential hormonal candidates for bud outgrowth control by sugar. They are central to future investigations aimed at disentangling the processes that underlie regulation of bud outgrowth by sugar.
Journal Article
Management of HIV-infected patients in the intensive care unit
by
Miller, Robert F
,
Mariotte Éric
,
Azoulay Élie
in
Acquired immune deficiency syndrome
,
Aging
,
AIDS
2020
The widespread use of combination antiretroviral therapies (cART) has converted the prognosis of HIV infection from a rapidly progressive and ultimately fatal disease to a chronic condition with limited impact on life expectancy. Yet, HIV-infected patients remain at high risk for critical illness due to the occurrence of severe opportunistic infections in those with advanced immunosuppression (i.e., inaugural admissions or limited access to cART), a pronounced susceptibility to bacterial sepsis and tuberculosis at every stage of HIV infection, and a rising prevalence of underlying comorbidities such as chronic obstructive pulmonary diseases, atherosclerosis or non-AIDS-defining neoplasms in cART-treated patients aging with controlled viral replication. Several patterns of intensive care have markedly evolved in this patient population over the late cART era, including a steady decline in AIDS-related admissions, an opposite trend in admissions for exacerbated comorbidities, the emergence of additional drivers of immunosuppression (e.g., anti-neoplastic chemotherapy or solid organ transplantation), the management of cART in the acute phase of critical illness, and a dramatic progress in short-term survival that mainly results from general advances in intensive care practices. Besides, there is a lack of data regarding other features of ICU and post-ICU care in these patients, especially on the impact of sociological factors on clinical presentation and prognosis, the optimal timing of cART introduction in AIDS-related admissions, determinants of end-of-life decisions, long-term survival, and functional outcomes. In this narrative review, we sought to depict the current evidence regarding the management of HIV-infected patients admitted to the intensive care unit.
Journal Article