Dye Chromoendoscopy Outperforms High-Definition White Light Endoscopy in Dysplasia Detection for Patients With Inflammatory Bowel Disease: An Updated Meta-Analysis of Randomized Controlled Trials

INTRODUCTION

Whether dye spray chromoendoscopy (DCE) adds value in surveillance colonoscopy with high-definition (HD) scopes remains controversial. This updated meta-analysis compares dysplasia detection using DCE and high-definition white light endoscopy (HD-WLE) in patients with inflammatory bowel disease (IBD) undergoing surveillance colonoscopy.

METHODS

A comprehensive search was performed for randomized controlled trials (RCT) comparing HD-WLE and DCE in patients with IBD. The primary outcome was to compare the proportion of patients with at least 1 dysplastic lesion detected by DCE vs HD-WLE. Odds ratios (OR) and 95% confidence intervals (CI) were pooled using the random-effects model, with I2 > 60% indicating substantial heterogeneity. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to assess the certainty of evidence (CoE).

RESULTS

Six RCT involving 978 patients were analyzed (DCE = 479 vs HD-WLE = 499 patients). DCE detected significantly more patients with dysplasia than HD-WLE (18.8% vs 9.4%), OR 1.94 (95% CI 1.21-3.11, I2 = 28%, P = 0.006, high CoE). This remained significant after excluding 2 RCT published as abstracts. A sensitivity analysis excluding a noninferiority RCT with a single experienced operator eliminated the results' heterogeneity, OR 2.46 (95% CI 1.56-3.90, I2 = 0%). Although high-grade dysplasia detection was numerically higher in the DCE group (2.8% vs 1.1%), the difference was statistically insignificant, OR 2.21 (95% CI 0.64-7.62, I2 = 0%, low CoE).

DISCUSSION

Our updated meta-analysis supports DCE as a superior strategy in overall dysplasia detection in IBD, even with HD scopes. When expertise is available, DCE should be considered for surveillance colonoscopy in patients with high-risk IBD, with the acknowledgment that virtual chromoendoscopy shows equivalence in recent studies. Further multicenter trials with multiple endoscopists with varying expertise levels and longer-term outcome data showing a reduction in cancer or cancer-related death are needed.

Long-term outcome of peripheral T-cell lymphomas: Ten-year follow-up of the International Prospective T-cell Project

Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of haematological cancers with generally poor clinical outcomes. However, a subset of patients experience durable disease control, and little is known regarding long-term outcomes. The International T-cell Lymphoma Project (ITCLP) is the largest prospectively collected cohort of patients with PTCLs, providing insight into clinical outcomes at academic medical centres globally. We performed a long-term outcome analysis on patients from the ITCLP with available 10-year follow-up data (n = 735). The overall response rate to first-line therapy was 68%, while 5- and 10-year overall survival estimates were 49% and 40% respectively. Most deaths occurred prior to 5 years, and for patients alive at 5 years, the chance of surviving to 10 years was 84%. However, lymphoma remained the leading cause of death in the 5- to 10-year period (67%). Low-risk International Prognostic Index and Prognostic Index for T-cell lymphoma scores both identified patients with improved survival, while in multivariate analysis, age >60 years and Eastern Cooperative Oncology Group performance status 2-4 were associated with inferior outcomes. The favourable survival seen in patients achieving durable initial disease control emphasizes the unmet need for optimal front-line therapeutic approaches in PTCLs.

A new oxidative pathway of nitric oxide production from oximes in plants

Nitric oxide (NO) is an essential reactive oxygen species and a signal molecule in plants. Although several studies have proposed the occurrence of oxidative NO production, only reductive routes for NO production, such as the nitrate (NO-3) -upper-reductase pathway, have been evidenced to date in land plants. However, plants grown axenically with ammonium as the sole source of nitrogen exhibit contents of nitrite and NO3-, evidencing the existence of a metabolic pathway for oxidative production of NO. We hypothesized that oximes, such as indole-3-acetaldoxime (IAOx), a precursor to indole-3-acetic acid, are intermediate oxidation products in NO synthesis. We detected the production of NO from IAOx and other oximes catalyzed by peroxidase (POD) enzyme using both 4-amino-5-methylamino-2',7'-difluorescein fluorescence and chemiluminescence. Flavins stimulated the reaction, while superoxide dismutase inhibited it. Interestingly, mouse NO synthase can also use IAOx to produce NO at a lower rate than POD. We provided a full mechanism for POD-dependent NO production from IAOx consistent with the experimental data and supported by density functional theory calculations. We showed that the addition of IAOx to extracts from Medicago truncatula increased the in vitro production of NO, while in vivo supplementation of IAOx and other oximes increased the number of lateral roots, as shown for NO donors, and a more than 10-fold increase in IAOx dehydratase expression. Furthermore, we found that in vivo supplementation of IAOx increased NO production in Arabidopsis thaliana wild-type plants, while prx33-34 mutant plants, defective in POD33-34, had reduced production. Our data show that the release of NO by IAOx, as well as its auxinic effect, explain the superroot phenotype. Collectively, our study reveals that plants produce NO utilizing diverse molecules such as oximes, POD, and flavins, which are widely distributed in the plant kingdom, thus introducing a long-awaited oxidative pathway to NO production in plants. This knowledge has essential implications for understanding signaling in biological systems.

Root phosphoenolpyruvate carboxylase activity is essential for Sorghum bicolor tolerance to ammonium nutrition

Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) is an enzyme family with pivotal roles in plant carbon and nitrogen metabolism. A main role for non-photosynthetic PEPC is as anaplerotic enzyme to load tricarboxylic acid (TCA) cycle with carbon skeletons that compensate the intermediates diverted for biomolecule synthesis such as amino acids. When plants are grown under ammonium (NH4+) nutrition, the excessive uptake of NH4+ often provokes a stress situation. When plants face NH4+ stress, N assimilation is greatly induced and thus, requires the supply of carbon skeletons coming from TCA cycle. In this work, we addressed the importance of root PEPC and TCA cycle for sorghum (Sorghum bicolor L. Moench), a C4 cereal crop, grown under ammonium nutrition. To do so, we used RNAi sorghum lines that display a decrease expression of SbPPC3 (Ppc3 lines), the main root PEPC isoform, and reduced root PEPC activity. SbPPC3 silencing provoked ammonium hypersensitivity, meaning lower biomass accumulation in Ppc3 respect to WT plants when growing under ammonium nutrition. The silenced plants presented a deregulation of primary metabolism as highlighted by the accumulation of NH4+ in the root and the alteration of normal TCA functioning, which was evidenced by the accumulation of organic acids in the root under ammonium nutrition. Altogether, our work evidences the importance of non-photosynthetic PEPC, and root TCA cycle, in sorghum to deal with high external NH4+ availability.

Interaction of ammonium nutrition with essential mineral cations

Plant growth and development depend on sufficient nutrient availability in soils. Agricultural soils are generally nitrogen (N) deficient, and thus soils need to be supplemented with fertilizers. Ammonium (NH4+) is a major inorganic N source. However, at high concentrations, NH4+ becomes a stressor that inhibits plant growth. The cause of NH4+ stress or toxicity is multifactorial, but the interaction of NH4+ with other nutrients is among the main determinants of plants' sensitivity towards high NH4+ supply. In addition, NH4+ uptake and assimilation provoke the acidification of the cell external medium (apoplast/rhizosphere), which has a clear impact on nutrient availability. This review summarizes current knowledge, at both the physiological and the molecular level, of the interaction of NH4+ nutrition with essential mineral elements that are absorbed as cations, both macronutrients (K+, Ca2+, Mg2+) and micronutrients (Fe2+/3+, Mn2+, Cu+/2+, Zn2+, Ni2+). We hypothesize that considering these nutritional interactions, and soil pH, when formulating fertilizers may be key in order to boost the use of NH4+-based fertilizers, which have less environmental impact compared with nitrate-based ones. In addition, we are convinced that better understanding of these interactions will help to identify novel targets with the potential to improve crop productivity.

The role of component separation in the treatment of severe diastasis recti abdominis: a new indication for a known technique

OBJECTIVE

Diastasis of the rectus abdominis muscle (DRAM) is a widening of linea alba, it also could be accompanied by abdominal bulging. DRAM is often a cause of quality-of-life impairment, especially when it is of large dimensions. Repair with direct rectus plication is the most common treatment for Diastasis Recti Abdominis (DRA), but it can result in high recurrence rates. The authors aimed to show their results in applying the component separation technique in wide DRA cases.

PATIENTS AND METHODS

From January 2015 to July 2018, 43 patients with DRA ≥ 10 cm at 3 cm over the umbilicus have been treated with component separation technique associated to panniculectomy. A biologic mesh was positioned onlay in cases of weakness along the semilunaris lines.

RESULTS

DRA repair was achieved in all cases. All patients completed the 1-year follow-up and no recurrence nor major complication were registered. Minor complications were observed in 12 (27.9%) cases.

CONCLUSIONS

This is the first study describing the component separation technique use in cases of DRA without hernia, associated to abdominoplasty surgery. Preliminary results were encouraging, but larger series are required.

Drug-Induced Acute Pancreatitis: An Evidence-Based Classification (Revised)

INTRODUCTION

Drug induced acute pancreatitis is a difficult diagnosis for clinicians. We previously published an "Evidence-Based Classification System" on Drug-Induced Acute Pancreatitis widely used by clinicians to assist in the identification of drugs. Unfortunately, this prior analysis based only on published case reports has been misunderstood. The prior review did not include studies with higher evidentiary value, such as randomized trials, case-control studies, and/or pharmacoepidemiologic studies. The use of the prior classification system has led to many patients being inappropriately labeled as having drug-induced acute pancreatitis. We now propose a "Revised" Evidence- Based Classification System for the purpose of determining which drugs cause acute pancreatitis based on the Grading of Recommendations, Development, and Evaluation criteria.

METHODS

A search of the English Language literature was performed to identify all case reports with medication and/or drug induced acute pancreatitis. We divided the drugs implicated as causing acute pancreatitis into four groups based on the quality of evidence as defined by GRADE quality parameters.

RESULTS

Although 141 drugs were identified in the literature as causing acute pancreatitis, only 106 drugs published in the literature as causing acute pancreatitis were high quality case reports. Only 3 drugs had evidence as causing acute pancreatitis from randomized controlled clinical trials, including 6-mercaptopurine and azathioprine.

DISCUSSION

The vast majority of drugs implicated as causing acute pancreatitis in the literature have low or very low quality of evidence supporting those claims.

Choledocholithiasis Can Present with Marked Transaminases Elevation: Systematic Review and Meta-Analysis

BACKGROUND

Extreme transaminase elevation > 1000 international units per liter (IU/L) is typically caused by hepatocellular injury due to ischemia, drugs, or viral infection. Acute choledocholithiasis can also present with marked transaminase elevation mimicking severe hepatocellular injury, contrary to the presumed cholestatic pattern.

METHODS

We searched PubMed/Medline, EMBASE, Cochrane Library, and Google Scholar for studies reporting the proportion of marked elevation of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 1000 IU/L in patients with common bile duct (CBD) stones. A proportion meta-analysis with a corresponding 95% confidence interval (CI) was used to pool the proportion of patients with extreme transaminase elevation. I² was used to examine heterogeneity. We used CMA software utilizing a random effect model for statistical analysis.

RESULTS

Three studies (n = 1328 patients) were included in our analysis. The reported frequency of ALT or AST > 1000 IU/L in choledocholithiasis patients ranged between 6 and 9.6%, with pooled frequency of 7.8% (95% CI 5.5-10.8%, I² 61%). The frequency of patients with ALT or AST > 500 IU/L was higher, ranging between 28 and 47%, with pooled frequency of 33.1% (95% CI 25.3-42%, I² 88%).

CONCLUSION

This is the first meta-analysis to study prevalence of severe hepatocellular injury in patients with CBD stones. Results revealed that approximately one-third of patients with choledocholithiasis present with ALT or AST > 500 IU/L. Furthermore, levels > 1000 IU/L are not uncommon. An elaborate work-up for alternative etiologies of severe transaminase elevation is likely unwarranted in cases with clear evidence of choledocholithiasis.

Etiologies and Outcomes of Transaminase Elevation > 1000 IU/L: A Systematic Review and Meta-Analysis

BACKGROUND

Among liver injury causes, few result in marked elevation of liver enzymes to a level > 1,000 international units per liter (IU/L). This review summarizes common etiologies of marked transaminase elevation and associated prognostic factors.

METHODS

We performed a comprehensive search on PubMed, EMBASE, Cochrane Library, and Google Scholar from inception through December 2022 using MOOSE guidelines for studies reporting frequency of etiologies of marked transaminase elevation. We used a proportion meta-analysis to pool frequencies with corresponding 95% confidence interval (CI). I² was used to adjudicate heterogeneity. We used CMA software for statistical analysis.

RESULTS

Seven relevant studies (n = 1608 patients) were included. The pooled frequency of ischemic hepatitis was 51% (95% CI 42-60%, I² = 91%), viral hepatitis was 13.1% (95% CI 9.7-17.6%, I² = 80%), toxins or drug-induced liver injury (DILI) was 13% (95% CI 8-18%, I² = 85%), and pancreaticobiliary-related injury was 7.8% (95% CI 4.4-13.6%, I² = 89%). Mortality was significantly higher in ischemic hepatitis versus other causes of marked transaminase elevation, with an odds ratio of 21 (95% CI 9.9-44.8, P value < 0.0001, I² = 64% Q 11.1).

DISCUSSION

This is the first meta-analysis to examine etiologies of marked transaminase elevation > 1000 IU/L. Liver ischemia is the most common cause, while other causes include DILI or toxins, viral hepatitis, and biliary pathologies. We found biliary pathologies to be the fourth most common cause. This is clinically relevant as it has been traditionally linked to a cholestatic pattern of liver injury. Being aware of this presentation may help prevent delayed or missed diagnoses and unnecessary testing.

Oxygenator impact on peramivir in extra-corporeal membrane oxygenation circuits

INTRODUCTION

This study aims to determine the oxygenator impact on alterations of peramivir (PRV) in a contemporary neonatal/pediatric (1/4-inch) and adolescent/adult (3/8-inch) extra-corporeal membrane oxygenation (ECMO) circuit including the Quadrox-i^® oxygenator.

METHODS

1/4-inch and 3/8-inch, simulated closed-loop ECMO circuits were prepared with a Quadrox-i pediatric and Quadrox-i adult oxygenator and blood primed. Additionally, 1/4-inch and 3/8-inch circuits were also prepared without an oxygenator in series. A one-time dose of PRV was administered into the circuits and serial pre- and post-oxygenator concentrations were obtained at 5-min and 1-, 2-, 3-, 4-, 5-, 6-, 8-, 12-, and 24-h time points. PRV was also maintained in a glass vial, and samples were taken from the vial at the same time periods for control purposes to assess for spontaneous drug degradation.

RESULTS

For the 1/4-in. circuit with an oxygenator, there was < 15% PRV loss, and for the 1/4-in. circuit without an oxygenator, there was < 3% PRV loss during the study period. For the 3/8-in. circuits with an oxygenator, there was < 15% PRV loss, and for the 3/8-in. circuits without an oxygenator, there was < 3% PRV loss during the study period.

CONCLUSION

There was no significant PRV loss over the 24-h study period in either the 1/4-in. or 3/8-in circuit, regardless of the presence of the oxygenator. The concentrations obtained pre- and post-oxygenator appeared to approximate each other, suggesting there may be no drug loss via the oxygenator. This preliminary data suggests PRV dosing may not need to be adjusted for concern of drug loss via the oxygenator. Additional single and multiple dose studies are needed to validate these findings.

DEGoldS: a workflow to assess the accuracy of differential expression analysis pipelines through gold-standard construction

Background:

Non-model species lacking public genomic resources have an extra handicap in bioinformatics that could be assisted by parameter tuning and the use of alternative software. Indeed, for RNA-seq-based gene differential expression analysis, parameter tuning could have a strong impact on the final results that should be evaluated. However, the lack of gold-standard datasets with known expression patterns hampers robust evaluation of pipelines and parameter combinations.

Objective:

The aim of the presented workflow is to assess the best differential expression analysis pipeline among several alternatives, in terms of accuracy. To achieve this objective, an automatic procedure of gold-standard construction for simulation-based benchmarking is implemented.

Methods:

The workflow, which is divided into four steps, simulates read libraries with known expression values to enable the construction of gold-standards for benchmarking pipelines in terms of true and false positives. We validated the workflow with a case study consisting of real RNA-seq libraries of radiata pine, a forest tree species with no publicly available reference genome.

method:

The workflow, which is divided into four steps, simulates reads libraries with known expression values that enable the construction of gold-standards for benchmarking pipelines in terms of true and false positives. We validated the workflow with a case study consisting on real RNA-seq libraries of radiata pine, a forest tree species with no publicly available reference genome.

Results:

The workflow is available as a freeware application (DEGoldS) consisting on sequential Bash and R scripts that can run in any UNIX OS platform. The presented workflow proved to be able to construct a valid gold-standard from real count data. Additionally, benchmarking showed that slight pipeline modifications produced remarkable differences in the outcome of differential expression analysis.

Conclusion:

The presented workflow solves the issues associated with robust gold-standard construction for benchmarking in differential expression experiments and can accommodate with a wide range of pipelines and parameter combinations.

other:

-

Treat-to-Target: The Era of Targeted Immunosuppressive Agents in IBD Management

With the advent of biologic agents, the treatment of patients with Inflammatory Bowel Diseases (IBD) has changed from managing symptoms to achieving remission of disease. Disease remission is associated with better outcomes than symptomatic care alone. The Treat-to-Target paradigm provides targets that serve as surrogates for achieving disease remission. The most important target is endoscopic mucosal healing and other targets include symptomatic response, symptomatic remission, biomarker normalization, and normalization of patient's quality of life. Targets are reached via utilization of biologic medications that may be modified or substituted as goals are not met. IBD Qorus represents a national collaborative of academic IBD centers and private gastroenterology practices using the Treat-to-Target approach and patient-centered communication methods to provide better care for all patient's suffering from IBD.

Impaired cell growth under ammonium stress explained by modeling the energy cost of vacuole expansion in tomato leaves

Ammonium (NH₄ ⁺ )-based fertilization efficiently mitigates the adverse effects of nitrogen fertilization on the environment. However, high concentrations of soil NH₄ ⁺ provoke growth inhibition, partly caused by the reduction of cell enlargement and associated with modifications of cell composition, such as an increase of sugars and a decrease in organic acids. Cell expansion depends largely on the osmotic-driven enlargement of the vacuole. However, the involvement of subcellular compartmentation in the adaptation of plants to ammonium nutrition has received little attention, until now. To investigate this, tomato (Solanum lycopersicum) plants were cultivated under nitrate and ammonium nutrition and the fourth leaf was harvested at seven developmental stages. The vacuolar expansion was monitored and metabolites and inorganic ion contents, together with intracellular pH, were determined. A data-constrained model was constructed to estimate subcellular concentrations of major metabolites and ions. It was first validated at the three latter developmental stages by comparison with subcellular concentrations obtained experimentally using non-aqueous fractionation. Then, the model was used to estimate the subcellular concentrations at the seven developmental stages and the net vacuolar uptake of solutes along the developmental series. Our results showed ammonium nutrition provokes an acidification of the vacuole and a reduction in the flux of solutes into the vacuoles. Overall, analysis of the subcellular compartmentation reveals a mechanism behind leaf growth inhibition under ammonium stress linked to the higher energy cost of vacuole expansion, as a result of alterations in pH, the inhibition of glycolysis routes and the depletion of organic acids.

Endoscopic Treatment of Reflux: A Comprehensive Review

The last decade has seen the rise of multiple novel endoscopic techniques to treat gastroesophageal reflux disease, many of which are efficacious when compared with traditional surgical options and allow relief from long-term dependence on antacid medications. This review will explore the latest endoscopic treatment options for gastroesophageal reflux disease including a description of the technique, review of efficacy and safety, and future directions.

Knock-down of phosphoenolpyruvate carboxylase 3 negatively impacts growth, productivity, and responses to salt stress in sorghum (Sorghum bicolor L.)

Phosphoenolpyruvate carboxylase (PEPC) is a carboxylating enzyme with important roles in plant metabolism. Most studies in C₄ plants have focused on photosynthetic PEPC, but less is known about non-photosynthetic PEPC isozymes, especially with respect to their physiological functions. In this work, we analyzed the precise roles of the sorghum (Sorghum bicolor) PPC3 isozyme by the use of knock-down lines with the SbPPC3 gene silenced (Ppc3 lines). Ppc3 plants showed reduced stomatal conductance and plant size, a delay in flowering time, and reduced seed production. In addition, silenced plants accumulated stress indicators such as Asn, citrate, malate, and sucrose in roots and showed higher citrate synthase activity, even in control conditions. Salinity further affected stomatal conductance and yield and had a deeper impact on central metabolism in silenced plants compared to wild type, more notably in roots, with Ppc3 plants showing higher nitrate reductase and NADH-glutamate synthase activity in roots and the accumulation of molecules with a higher N/C ratio. Taken together, our results show that although SbPPC3 is predominantly a root protein, its absence causes deep changes in plant physiology and metabolism in roots and leaves, negatively affecting maximal stomatal opening, growth, productivity, and stress responses in sorghum plants. The consequences of SbPPC3 silencing suggest that this protein, and maybe orthologs in other plants, could be an important target to improve plant growth, productivity, and resistance to salt stress and other stresses where non-photosynthetic PEPCs may be implicated.

Is plastidic glutamine synthetase essential for C3 plants? A tale of photorespiratory mutants, ammonium tolerance and conifers

Agriculture faces the considerable challenge of having to adapt to a progressively changing climate (including the increase in CO₂ levels and temperatures); environmental impact must be reduced while at the same time crop yields need to be maintained or increased to ensure food security. Under this scenario, increasing plants' nitrogen (N) use efficiency and minimizing the energy losses associated with photorespiration are two goals of crop breeding that are long sought after. The plastidic glutamine synthetase (GS2) enzyme stands at the crossroads of N assimilation and photorespiration, and is therefore a key candidate for the improvement of crop performance. The GS2 enzyme has long been considered essential for angiosperm survival under photorespiratory conditions. Surprisingly, in Arabidopsis GS2 is not essential for plant survival, and its absence confers tolerance towards ammonium stress, which is in conflict with the idea that NH₄⁺ accumulation is one of the main causes of ammonium stress. Altogether, it appears that the 'textbook' view of this enzyme must be revisited, especially regarding the degree to which it is essential for plant growth under photorespiratory conditions, and the role of NH₄⁺ assimilation during ammonium stress. In this article we open the debate on whether more or less GS2 is a desirable trait for plant productivity.

Per Oral Endoscopic Myotomy for Zenker's Diverticulum: A Novel and Superior Technique Compared With Septotomy?

INTRODUCTION

Endoscopic management of Zenker diverticuli (ZD) has traditionally been via septotomy technique. The recent development of tunneling technique has shown to be both efficacious and safe. The aim of this study is to evaluate the tunneling technique using per oral endoscopic myotomy (Z-POEM) versus septotomy.

METHODS

Patients who underwent endoscopic management of ZD either by Z-POEM or septotomy from March 2017 until November 2020 from 9 international academic centers were included. Demographics, clinical data preprocedure and postprocedure, procedure time, adverse events, and hospital length of stay were analyzed.

RESULTS

A total of 101 patients (mean age 74.9 y old, 55.4% male) were included: septotomy (n=49), Z-POEM (n=52). Preprocedure Functional Oral Intake Scale score and Eckardt score was 5.3 and 5.4 for the septotomy group and 5.9 and 5.15 for the Z-POEM group. Technical success was achieved in 98% of the Z-POEM group and 100% of the septotomy group. Clinical success was achieved in 84% and 92% in the septotomy versus Z-POEM groups. Adverse events occurred in 30.6% (n=15) in septotomy group versus 9.6% (n=5) in the Z-POEM group (P=0.017). Reintervention for ongoing symptoms occurred in 7 patients in the septotomy group and 3 patients in the Z-POEM group. Mean hospital length of stay was shorter for the Z-POEM group, at 1.5 versus 1.9 days.

CONCLUSIONS

A tunneling technique via the Z-POEM procedure is an efficacious and safe endoscopic treatment for ZD. Z-POEM is a safer procedure with a statistically significant reduction in adverse events compared with traditional septotomy technique.

Ammonium nutrition interacts with iron homeostasis in Brachypodium distachyon

Most plant species develop stress symptoms when exposed to high ammonium (NH4+) concentrations. The root is the first organ in contact with high NH4+ and therefore the first barrier to cope with ammonium stress. In this work, we focused on root adaptation to ammonium nutrition in the model plant Brachypodium distachyon. Proteome analysis revealed changes associated with primary metabolism, cell wall remodelling, and redox homeostasis. In addition, it showed a strong induction of proteins related to methionine (Met) metabolism and phytosiderophore (PS) synthesis in ammonium-fed plants. In agreement with this, we show how ammonium nutrition impacts Met/S-adenosyl-Met and PS metabolic pathways together with increasing root iron content. Nevertheless, ammonium-fed plants displayed higher sensitivity to iron deficiency, suggesting that ammonium nutrition triggers impaired iron utilization and root to shoot transport, which entailed an induction in iron-related responses. Overall, this work demonstrates the importance of iron homeostasis during ammonium nutrition and paves a new way to better understand and improve ammonium use efficiency and tolerance.

Gastrointestinal histopathology of acute colchicine toxicity after lower dose treatment of pericarditis: A case report

Colchicine is an anti-inflammatory alkaloid drug with anti-microtubule activity. Colchicine toxicity is a serious and potentially fatal complication associated with hallmark histopathological features most conspicuous in proliferative tissues such as the gastrointestinal tract. These features have only been reported in patients treated with high doses. We report a patient who experienced acute colchicine toxicity with gastrointestinal histologic changes after treatment with the lowest dose of colchicine. Knowledge of drug-drug interactions and the organs involved in colchicine metabolism is imperative when using colchicine, even when administered at its lowest dose.

Increased serum selenium levels are associated with reduced risk of advanced liver fibrosis and all-cause mortality in NAFLD patients: National Health and Nutrition Examination Survey (NHANES) III

INTRODUCTION AND OBJECTIVES

Selenium supplementation has been shown to have therapeutic value in chronic liver disease. We aimed to investigate the association between serum selenium, severity of liver fibrosis, and mortality in patients with Nonalcoholic Fatty Liver Disease (NAFLD).

PATIENTS OR MATERIAL AND METHODS

A total of 33,944 patients were identified from the Third National Health and Nutrition Examination Survey. NAFLD was diagnosed by hepatic ultrasound after the exclusion of other forms of liver diseases. The severity of liver fibrosis was determined by NAFLD Fibrosis Score >0.676. Multivariate logistic regression analysis was used to investigate the relationship between serum selenium level and liver fibrosis. Association between serum selenium and all-cause mortality in NAFLD patients was also evaluated.

RESULTS

Multivariate logistic regression analysis demonstrated odds ratio of advanced liver fibrosis (NFS > 0.676) was significantly reduced with increasing serum selenium levels; OR 0.55, [95% CI 0.32-0.94] in the highest selenium quartile. On stratification analysis, the following populations had a significantly reduced risk of advanced liver fibrosis: non-Hispanic white = OR 0.41 [0.24,0.68]; female = OR 0.32 [0.15-0.66] and age >47 = OR 0.47 [0.28-0.79]. The relationship was significant regardless of BMI as noted by BMI ≤ 30 Kg/m2= OR 0.42 [0.19-0.91] and BMI > 30 Kg/m2=OR 0.52 [0.28-0.97]. Hazard ratio for all-cause mortality was HR 0.72 [0.56-0.95].

CONCLUSIONS

The risk of advanced liver fibrosis is inversely associated with serum selenium levels, particularly in older patients, Caucasians, and females. All-cause mortality decreased with increased selenium levels. Selenium may play a role in the prevention of liver fibrosis in NAFLD.

Immunomodulatory agents as potential therapeutic or preventive strategies for COVID-19

Currently, the COVID-19 pandemic, caused by the novel SARS-CoV-2 coronavirus, represents the greatest global health threat. Most people infected by the virus present mild to moderate respiratory symptoms and recover with supportive treatments. However, certain susceptible hosts develop an acute respiratory distress syndrome (ARDS), associated with an inflammatory "cytokine storm", leading to lung damage. Despite the current availability of different COVID-19 vaccines, the new emerging SARS-CoV-2 genetic variants represent a major concern worldwide, due to their increased transmissibility and rapid spread. Indeed, it seems that some mutations or combinations of mutations might confer selective advantages to the virus, such as the ability to evade the host immune responses elicited by COVID-19 vaccines. Several therapeutic approaches have been investigated but, to date, a unique and fully effective therapeutic protocol has not yet been achieved. In addition, steroid-based therapies, aimed to reduce inflammation in patients with severe COVID-19 disease, may increase the risk of opportunistic infections, increasing the hospitalization time and mortality rate of these patients. Hence, there is an unmet need to develop more effective therapeutic options. Here, we discuss the potential use of natural immunomodulators such as Thymosin α1 (Tα1), all-trans retinoic acid (ATRA), and lactoferrin (LF), as adjunctive or preventive treatment of severe COVID-19 disease. These agents are considered to be multifunctional molecules because of their ability to enhance antiviral host immunity and restore the immune balance, depending on the host immune status. Furthermore, they are able to exert a broad-spectrum antimicrobial activity by means of direct interactions with cellular or molecular targets of pathogens or indirectly by increasing the host immune response. Thus, due to the aforementioned properties, these agents might have a great potential in a clinical setting, not only to counteract SARS-CoV-2 infection, but also to prevent opportunistic infections in critically ill COVID-19 patients.

Oxygenator impact on meropenem/vaborbactam in extracorporeal membrane oxygenation circuits

INTRODUCTION

To determine the oxygenator impact on alterations of meropenem (MEM)/vaborbactam (VBR) in a contemporary neonatal/pediatric (1/4-inch) and adolescent/adult (3/8-inch) extra corporeal membrane oxygenation (ECMO) circuit including the Quadrox-i^® oxygenator.

METHODS

1/4-inch and 3/8-inch, simulated closed-loop ECMO circuits were prepared with a Quadrox-i pediatric and Quadrox-i adult oxygenator and blood primed. Additionally, 1/4-inch and 3/8-inch circuits were also prepared without an oxygenator in series. A one-time dose of MEM/VBR was administered into the circuits and serial pre- and post-oxygenator concentrations were obtained at 5 minutes, 1, 2, 3, 4, 5, 6, 8, 12, and 24-hour time points. MEM/VBR was also maintained in a glass vial and samples were taken from the vial at the same time periods for control purposes to assess for spontaneous drug degradation.

RESULTS

For the 1/4-inch circuit, there was an approximate mean 55% MEM loss with the oxygenator in series and a mean 33%-40% MEM loss without an oxygenator in series at 24 hours. For the 3/8-inch circuit, there was an approximate mean 70% MEM loss with the oxygenator in series and a mean 30%-38% MEM loss without an oxygenator in series at 24 hours. For both the 1/4-inch circuit and 3/8-inch circuits with and without an oxygenator, there was <10% VBR loss for the duration of the experiment.

CONCLUSIONS

This ex-vivo investigation demonstrated substantial MEM loss within an ECMO circuit with an oxygenator in series with both sizes of the Quadrox-i oxygenator at 24 hours and no significant VBR loss. Further evaluations with multiple dose in-vitro and in-vivo investigations are needed before specific MEM/VBR dosing recommendations can be made for clinical application with ECMO.

Renal Failure is Associated With Increased Mortality and Hospital Utilization in Patients Admitted With Nonalcoholic Steatohepatitis

GOALS

We aimed to investigate the mortality and hospital utilization outcomes of hospitalized nonalcoholic steatohepatitis (NASH) patients with and without kidney failure in a nationwide cohort.

BACKGROUND

NASH is a common medical condition associated with significant morbidity and mortality. A paucity of data exists regarding the impact of kidney failure (defined as acute and chronic kidney failure) on outcomes of NASH hospitalizations.

MATERIALS AND METHODS

We conducted a retrospective cohort study using the 2016 Nationwide Inpatient Sample dataset of adult patients hospitalized for NASH, stratified for the presence of renal failure. The primary outcome was inpatient mortality, predictors were analyzed using multivariate logistic regression. Secondary outcomes were the length of stay and mean total hospitalization charges.

RESULTS

The overall sample included 7,135,090 patients. Among 6855 patients admitted for NASH, 598 or 8.7% had comorbid kidney failure. After multivariate regression analysis, NASH patients with renal failure had increased in-hospital mortality [odds ratio=28.72, 95% confidence interval (CI): 8.99-91.73], length of stay (β=3.02, 95% CI: 2.54-3.5), total hospital charges (β=$37,045, 95% CI: $31,756.18-$42,335.62). Positive predictors of mortality in the renal failure group were Charlson Comorbidity Index ≥3 [adjusted odds ratio (aOR)=3.46, 95% CI: 1.04-11.51], variceal bleeding (aOR=3.02, 95% CI: 1.06-8.61), and hepatic encephalopathy (aOR=26.38, 95% CI: 1.29-540.56). Predictors of decreased mortality were Medicaid (aOR=0.047, 95% CI: 0.28-0.79) and private insurance (aOR=0.56, 95% CI: 0.38-0.83).

CONCLUSIONS

The prevalence of renal failure in NASH hospitalizations is associated with markedly increased mortality, hospital costs, and length of stay. As a result, clinicians should be vigilant in treating kidney failure in this population.

Arabidopsis MYB28 and MYB29 transcription factors are involved in ammonium-mediated alterations of root-system architecture

Ammonium (NH₄⁺) is known to produce alterations in root-system architecture, notably, by inhibiting primary root elongation and stimulating lateral root branching. This stimulation is associated with higher auxin transport promoted by apoplast acidification. Recently, we showed that MYB28 and MYB29 transcription factors play a role in ammonium tolerance, since its double mutant (myb28myb29) is highly hypersensitive toward ammonium nutrition in relation to altered Fe homeostasis. In the present work, we observed that primary root elongation was lower in the mutant with respect to wild-type plants under ammonium nutrition. Moreover, ammonium-induced lateral root branching was impaired in myb28myb29 in a Fe-supply dependent manner. Further research is required to decipher the link between MYB28 and MYB29 functions and the signaling pathway leading to root-system architecture modification by NH₄⁺ supply.

Ammonium supply induces differential metabolic adaptive responses in tomato according to leaf phenological stage

Nitrate (NO3-) and ammonium (NH4+) are the main inorganic nitrogen sources available to plants. However, exclusive ammonium nutrition may lead to stress characterized by growth inhibition, generally associated with a profound metabolic reprogramming. In this work, we investigated how metabolism adapts according to leaf position in the vertical axis of tomato (Solanum lycopersicum cv. M82) plants grown with NH4+, NO3-, or NH4NO3 supply. We dissected leaf biomass composition and metabolism through an integrative analysis of metabolites, ions, and enzyme activities. Under ammonium nutrition, carbon and nitrogen metabolism were more perturbed in mature leaves than in young ones, overall suggesting a trade-off between NH4+ accumulation and assimilation to preserve young leaves from ammonium stress. Moreover, NH4+-fed plants exhibited changes in carbon partitioning, accumulating sugars and starch at the expense of organic acids, compared with plants supplied with NO3-. We explain such reallocation by the action of the biochemical pH-stat as a mechanism to compensate the differential proton production that depends on the nitrogen source provided. This work also underlines that the regulation of leaf primary metabolism is dependent on both leaf phenological stage and the nitrogen source provided.

A Multi-Species Analysis Defines Anaplerotic Enzymes and Amides as Metabolic Markers for Ammonium Nutrition

Nitrate and ammonium are the main nitrogen sources in agricultural soils. In the last decade, ammonium (NH4 +), a double-sided metabolite, has attracted considerable attention by researchers. Its ubiquitous presence in plant metabolism and its metabolic energy economy for being assimilated contrast with its toxicity when present in high amounts in the external medium. Plant species can adopt different strategies to maintain NH4 + homeostasis, as the maximization of its compartmentalization and assimilation in organic compounds, primarily as amino acids and proteins. In the present study, we report an integrative metabolic response to ammonium nutrition of seven plant species, belonging to four different families: Gramineae (ryegrass, wheat, Brachypodium distachyon), Leguminosae (clover), Solanaceae (tomato), and Brassicaceae (oilseed rape, Arabidopsis thaliana). We use principal component analysis (PCA) and correlations among metabolic and biochemical data from 40 experimental conditions to understand the whole-plant response. The nature of main amino acids is analyzed among species, under the hypothesis that those Asn-accumulating species will show a better response to ammonium nutrition. Given the provision of carbon (C) skeletons is crucial for promotion of the nitrogen assimilation, the role of different anaplerotic enzymes is discussed in relation to ammonium nutrition at a whole-plant level. Among these enzymes, isocitrate dehydrogenase (ICDH) shows to be a good candidate to increase nitrogen assimilation in plants. Overall, metabolic adaptation of different carbon anaplerotic activities is linked with the preference to synthesize Asn or Gln in their organs. Lastly, glutamate dehydrogenase (GDH) reveals as an important enzyme to surpass C limitation during ammonium assimilation in roots, with a disparate collaboration of glutamine synthetase (GS).

Arabidopsis thaliana transcription factors MYB28 and MYB29 shape ammonium stress responses by regulating Fe homeostasis

Although ammonium (NH₄⁺ ) is a key intermediate of plant nitrogen metabolism, high concentrations of NH₄⁺ in the soil provoke physiological disorders that lead to the development of stress symptoms. Ammonium nutrition was shown to induce the accumulation of glucosinolates (GSLs) in leaves of different Brassicaceae species. To further understand the link between ammonium nutrition and GSLs, we analysed the ammonium stress response of Arabidopsis mutants impaired in GSL metabolic pathway. We showed that the MYB28 and MYB29 double mutant (myb28myb29), which is almost deprived of aliphatic GSLs, is highly hypersensitive to ammonium nutrition. Moreover, we evidenced that the stress symptoms developed were not a consequence of the lack of aliphatic GSLs. Transcriptomic analysis highlighted the induction of an iron (Fe) deficiency response in myb28myb29 under ammonium nutrition. Consistently, ammonium-grown myb28myb29 plants showed altered Fe accumulation and homeostasis. Interestingly, we showed overall that growing Arabidopsis with increased Fe availability relieved ammonium stress symptoms and that this was associated with MYB28 and MYB29 expression. Taken together, our data indicated that the control of Fe homeostasis was crucial for the Arabidopsis response to ammonium nutrition and evidenced that MYB28 and MYB29 play a role in this control.

Antimicrobial properties of the medicinal plant Cardiospermum halicacabum L: new evidence and future perspectives

The emergence and rapid spread of multidrug-resistance in human pathogenic microorganisms urgently require the development of novel therapeutic strategies for the treatment of infectious diseases. From this perspective, the antimicrobial properties of the natural plant-derived products may represent an important alternative therapeutic option to synthetic drugs. Among medicinal plants, the Cardiospermum halicacabum L. (C. halicacabum), belonging to Sapindaceae family, could be a very promising candidate for its antimicrobial activity against a wide range of microorganisms, including both Gram-positive and Gram-negative bacteria, as well as fungal pathogens. Although the antimicrobial properties of C. halicacabum have been intensively studied, the mechanism/s by which it exerts the inhibitory activity towards the pathogenic microbes have not yet been completely understood. This review focuses on the main antimicrobial activities displayed in vitro by the plant extract, with particular attention on our recent advances. We demonstrated that C. halicacabum is able to exert in vitro a dose-dependent fungistatic effect against Trychophyton rubrum (T. rubrum) through molecular interaction with the fungal heat shock protein (Hsp)-90 chaperone. These findings are supported by a growing body of research indicating the crucial role played by the Hsp90 in the virulence of the pathogenic microorganisms, including fungal pathogens. The possible future use of C. halicacabum for treating a wide range of infectious diseases is also discussed.

The Arabidopsis Transcription Factor CDF3 Is Involved in Nitrogen Responses and Improves Nitrogen Use Efficiency in Tomato

Nitrate is an essential macronutrient and a signal molecule that regulates the expression of multiple genes involved in plant growth and development. Here, we describe the participation of Arabidopsis DNA binding with one finger (DOF) transcription factor CDF3 in nitrate responses and shows that CDF3 gene is induced under nitrate starvation. Moreover, knockout cdf3 mutant plants exhibit nitrate-dependent lateral and primary root modifications, whereas CDF3 overexpression plants show increased biomass and enhanced root development under both nitrogen poor and rich conditions. Expression analyses of 35S::CDF3 lines reveled that CDF3 regulates the expression of an important set of nitrate responsive genes including, glutamine synthetase-1, glutamate synthase-2, nitrate reductase-1, and nitrate transporters NRT2.1, NRT2.4, and NRT2.5 as well as carbon assimilation genes like PK1 and PEPC1 in response to N availability. Consistently, metabolite profiling disclosed that the total amount of key N metabolites like glutamate, glutamine, and asparagine were higher in CDF3-overexpressing plants, but lower in cdf3-1 in N limiting conditions. Moreover, overexpression of CDF3 in tomato increased N accumulation and yield efficiency under both optimum and limiting N supply. These results highlight CDF3 as an important regulatory factor for the nitrate response, and its potential for improving N use efficiency in crops.

One-year risk of opioid use disorder after index hospitalization for inflammatory bowel disease

PURPOSE

Patients with inflammatory bowel disease are commonly prescribed opiates for pain. We sought to determine the incidence of opiate use disorder after inflammatory bowel disease (IBD) admission over a 1-year period as well as its impact on mortality and hospital resource utilization.

METHODS

The Nationwide Readmission Database 2016 was used to identify adult patients with a principal diagnosis of IBD who were subsequently readmitted with a primary diagnosis of opioid use disorder. The primary outcome was 1-year readmission rate for opiate use disorder. Predictors were analyzed using multivariate logistic regression. Secondary outcomes were mortality rate, length of stay, and total hospital costs and charges.

RESULTS

Among the 6340 index hospitalizations for IBD, 4.7% (6.0% Crohn's and 2.6% ulcerative colitis) were readmitted within 1 year for opiate use disorder. Readmission hospitalizations were associated with additional mortality (0.32%) and hospital utilization (length of stay 4.80 days, mean total costs $9503, and mean total charges $38,288). Ulcerative colitis had significantly higher mortality and hospital utilization costs compared with Crohn's disease. In multivariable analysis, odds of readmission were associated with female sex (OR 1.51, CI 1.19-1.92), private insurance (OR 0.20, CI 0.11-0.37), Charlson Comorbidity Index (OR 0.20, CI 0.11-0.37), anxiety (OR 1.65, CI 1.02-2.63), and depression (OR 2.07, CI 1.28-3.34). On stratification analysis, psychiatric comorbidities were associated with both Crohn's and ulcerative colitis.

CONCLUSION

Patients with IBD were often readmitted for opiate use disorder and sustained significant mortality and hospital costs. Psychiatric comorbidities, gender, and insurance status impacted the odds of readmission and represent targets for intervention.

Correction to: "Which Factors Correlate with Marginal Ulcer After Surgery for Obesity?"

In the original article, the author names were presented incorrectly; their family names and given names were inverted.

Apremilast as a target therapy for nail psoriasis: a real-life observational study proving its efficacy in restoring the nail unit

PURPOSE

Psoriasis, Psoriatic Arthritis and Nail psoriasis are chronic diseases that share a common underlying etiology of immunity dysregulation, enhanced activation of inflammatory pathways and remitting-relapsing course. Although nails represent a small percentage of the body surface involvement of this site can lead to impaired quality of life, severe discomfort and even result in permanent disability. Current therapeutic options for nail psoriasis include a variety of topical and systemic treatments although they are often reported as unsatisfactory from patients either due to their poor effectiveness or disturbing side effects. Recently small molecule drugs such as the PDE4 inhibitors were introduced in clinical practice and specifically apremilast has shown to be an effective new treatment option for psoriasis and psoriatic arthritis. Considering either the specific mechanism of action of apremilast, we performed a real-life observational study of 24 weeks assessing apremilast role in nail psoriasis.

MATHERIALS AND METHODS

Patients received apremilast 30mg bid, orally. Safety and efficacy were assessed at weeks 0, 4, 8, 12 and 24 using Dermatologic Life Quality Index (DLQI) and Nail Area Psoriasis Severity Index (NAPSI). At T0 we took a nail sample to investigate the presence of onychomycosis. Culture tests were performed in all the patients to search for fungi.

RESULTS

We recruited a total of 15 patients with nail psoriasis. The analysis of variance (one-way ANOVA) showed the following results: DLQI (F.15.7; p-value < .00001) and NAPSI (F.9.4; p-value < .00001). Three patients (20%) presented also onychomycoses at the beginning of the treatment.

CONCLUSIONS

Apremilast showed fast and sustained improvement of nail psoriasis over time and a complete resolution of life quality impairment due to the disease.

Oxygenator impact on voriconazole in extracorporeal membrane oxygenation circuits

INTRODUCTION

To determine the oxygenator impact on alterations of voriconazole in a contemporary neonatal/pediatric (1/4 inch) and adolescent/adult (3/8 inch) extracorporeal membrane oxygenation circuit including the Quadrox-i^® oxygenator.

METHODS

Simulated closed-loop extracorporeal membrane oxygenation circuits (1/4 and 3/8 inch) were prepared with a Quadrox-i pediatric and Quadrox-i adult oxygenator and blood primed. In addition, 1/4- and 3/8-inch circuits were also prepared without an oxygenator in series. A one-time dose of voriconazole was administered into the circuits, and serial pre- and post-oxygenator concentrations were obtained at 5 minutes, 1, 2, 3, 4, 5, 6, and 24 hour time points. Voriconazole was also maintained in a glass vial and samples were taken from the vial at the same time periods for control purposes to assess for spontaneous drug degradation.

RESULTS

For the 1/4-inch circuit, there was an approximate mean of 64-67% voriconazole loss with the oxygenator in series and mean of 15-20% voriconazole loss without an oxygenator in series at 24 hours. For the 3/8-inch circuit, there was an approximate mean of 44-51% voriconazole loss with the oxygenator in series and a mean of 8-12% voriconazole loss without an oxygenator in series at 24 hours. The reference voriconazole concentrations remained relatively constant during the entire study period demonstrating that the drug loss in each size of the extracorporeal membrane oxygenation circuit with or without an oxygenator was not a result of spontaneous drug degradation.

CONCLUSION

This ex vivo investigation demonstrated substantial voriconazole loss within an extracorporeal membrane oxygenation circuit with an oxygenator in series with both sizes of the Quadrox-i oxygenator at 24 hours and no significant voriconazole loss in the absence of an oxygenator. Further evaluations with multiple dose in vitro and in vivo investigations are needed before specific voriconazole dosing recommendations can be made for clinical application with extracorporeal membrane oxygenation.

Medical infrared thermal imaging of syringomyelia in the Cavalier King Charles Spaniel

Background

Medical infrared thermal imaging (MITI) is a non-invasive imaging modality gaining popularity in the veterinary field. An infrared camera captures emission of heat and creates a color map in the form of a thermogram. Topical heat emission is influenced by localized disease processes as a result of autonomic nervous system imbalance. The purpose of this study was to determine the utility of using thermography to identify changes in thermographic patterns associated with syringomyelia (SM) presence or absence in Cavalier King Charles Spaniels (CKCS) with Chiari-like Malformation (CLM).

Results

In CKCS with CLM, MITI was most accurate at a texture distance of 6. Optimizing imaging feature sets produced a highest accuracy of 69.9% (95% CI: 59.5–79.0%), with 81.3% sensitivity and 57.8% specificity for identifying the presence of syringomyelia.

Conclusion

Thermographic image analysis is a successful non-invasive, diagnostic test that can be used to screen for syringomyelia presence in a CKCS with CLM.

Medical infrared thermal imaging of canine appendicular bone neoplasia

Background

Medical infrared thermal imaging (MITI) is a noninvasive imaging modality used in veterinary medicine as a screening tool for musculoskeletal and neurological disease processes. An infrared camera measures the surface body heat and produces a color map that represents the heat distribution. Local trauma or disease can impair the autonomic nervous system, which leads to changes in the local dermal microcirculation and subsequent alteration of surface body heat. Disruption of autonomic flow to the cutaneous vasculature at deeper levels can also result in asymmetric thermographic results. The purpose of this study was to evaluate surface temperature differences between limbs affected by bone neoplasia and their normal contralateral limbs.

Results

A statistically significant difference in average temperature was noted between regions of interest of the two groups (paired difference: 0.53 C° ± 0.14; P = 0.0005). In addition, pattern recognition analysis yielded a 75–100% success rate in lesion identification.

Conclusions

Significant alterations noted with average temperature and thermographic patterns indicate that MITI can document discernible changes associated with the presence of canine appendicular bone tumors. While MITI cannot be used as the sole diagnostic tool for bone cancer, it can be used as a screening modality and may be applicable in early detection of cancer.

IAOx induces the SUR phenotype and differential signalling from IAA under different types of nitrogen nutrition in Medicago truncatula roots

Indole-3-acetaldoxime (IAOx) is a particularly relevant molecule as an intermediate in the pathway for tryptophan-dependent auxin biosynthesis. The role of IAOx in growth-signalling and root phenotype is poorly studied in cruciferous plants and mostly unknown in non-cruciferous plants. We synthesized IAOx and applied it to M. truncatula plants grown axenically with NO₃^-, NH₄⁺ or urea as the sole nitrogen source. During 14 days of growth, we demonstrated that IAOx induced an increase in the number of lateral roots, especially under NH₄⁺ nutrition, while elongation of the main root was inhibited. This phenotype is similar to the phenotype known as "superroot" previously described in SUR1- and SUR2-defective Arabidopsis mutants. The effect of IAOx, IAA or the combination of both on the root phenotype was different and dependent on the type of N-nutrition. Our results also showed the endogenous importance of IAOx in a legume plant in relation to IAA metabolism, and suggested IAOx long-distance transport depending on the nitrogen source provided. Finally, our results point out to CYP71A as the major responsible enzymes for IAA synthesis from IAOx, while they exclude indole-3-acetaldehyde oxidases.

Isotopic labelling reveals the efficient adaptation of wheat root TCA cycle flux modes to match carbon demand under ammonium nutrition

Proper carbon (C) supply is essential for nitrogen (N) assimilation especially when plants are grown under ammonium (NH4+) nutrition. However, how C and N metabolic fluxes adapt to achieve so remains uncertain. In this work, roots of wheat (Triticum aestivum L.) plants grown under exclusive NH4+ or nitrate (NO3-) supply were incubated with isotope-labelled substrates (15NH4+, 15NO3-, or [13C]Pyruvate) to follow the incorporation of 15N or 13C into amino acids and organic acids. Roots of plants adapted to ammonium nutrition presented higher capacity to incorporate both 15NH4+ and 15NO3- into amino acids, thanks to the previous induction of the NH4+ assimilative machinery. The 15N label was firstly incorporated into [15N]Gln vía glutamine synthetase; ultimately leading to [15N]Asn accumulation as an optimal NH4+ storage. The provision of [13C]Pyruvate led to [13C]Citrate and [13C]Malate accumulation and to rapid [13C]2-OG consumption for amino acid synthesis and highlighted the importance of the anaplerotic routes associated to tricarboxylic acid (TCA) cycle. Taken together, our results indicate that root adaptation to ammonium nutrition allowed efficient assimilation of N thanks to the promotion of TCA cycle open flux modes in order to sustain C skeleton availability for effective NH4+ detoxification into amino acids.

Providing carbon skeletons to sustain amide synthesis in roots underlines the suitability of Brachypodium distachyon for the study of ammonium stress in cereals

Plants mainly acquire N from the soil in the form of nitrate (NO₃ ^-) or ammonium (NH₄ ⁺). Ammonium-based nutrition is gaining interest because it helps to avoid the environmental pollution associated with nitrate fertilization. However, in general, plants prefer NO₃ ^- and indeed, when growing only with NH₄ ⁺ they can encounter so-called ammonium stress. Since Brachypodium distachyon is a useful model species for the study of monocot physiology and genetics, we chose it to characterize performance under ammonium nutrition. Brachypodium distachyon Bd21 plants were grown hydroponically in 1 or 2.5 mM NO₃ ^- or NH₄ ⁺. Nitrogen and carbon metabolism associated with NH₄ ⁺ assimilation was evaluated in terms of tissue contents of NO₃ ^-, NH₄ ⁺, K, Mg, Ca, amino acids and organic acids together with tricarboxylic acid (TCA) cycle and NH₄ ⁺-assimilating enzyme activities and RNA transcript levels. The roots behaved as a physiological barrier preventing NH₄ ⁺ translocation to aerial parts, as indicated by a sizeable accumulation of NH₄ ⁺, Asn and Gln in the roots. A continuing high NH₄ ⁺ assimilation rate was made possible by a tuning of the TCA cycle and its associated anaplerotic pathways to match 2-oxoglutarate and oxaloacetate demand for Gln and Asn synthesis. These results show B. distachyon to be a highly suitable tool for the study of the physiological, molecular and genetic basis of ammonium nutrition in cereals.

Multi-omic and physiologic approach to understand Lotus japonicus response upon exposure to 3,4 dimethylpyrazole phosphate nitrification inhibitor

Nitrogen fertilization is a major force in global greenhouse gases emissions and causes environmental contamination through nitrate leaching. The use of nitrification inhibitors has been proven successful to mitigate these effects. However, there is an increasing concern about the undesired effects that their potential persistence in the soil or accumulation in plants may provoke. In this study, we first exposed Lotus japonicus plants to high amounts of 3,4 dimethylpyrazole phosphate (DMPP) and 2-(N-3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA) nitrification inhibitors. Exposure to doses higher than 1 mg·L^-1 provoked DMPP accumulation mostly in the aerial part, while DMPSA was only detected from 10 mg·L^-1 and nearly no translocation. To evaluate the effect that DMPP accumulation in leaves may provoke on plant performance we combined a transcriptome, proteome, and physiological analysis in plants treated with 10 mg/ L of DMPP. This treatment provoked changes in the expression of 229 genes and 59 proteins. Overall, we evidence that when DMPP accumulates in leaves it induces stress responses, notably provoking changes in cell redox balance, hormone signaling, protein synthesis and turnover and carbon and nitrogen metabolism.

New Insights on Arabidopsis thaliana Root Adaption to Ammonium Nutrition by the Use of a Quantitative Proteomic Approach

Nitrogen is an essential element for plant nutrition. Nitrate and ammonium are the two major inorganic nitrogen forms available for plant growth. Plant preference for one or the other form depends on the interplay between plant genetic background and environmental variables. Ammonium-based fertilization has been shown less environmentally harmful compared to nitrate fertilization, because of reducing, among others, nitrate leaching and nitrous oxide emissions. However, ammonium nutrition may become a stressful situation for a wide range of plant species when the ion is present at high concentrations. Although studied for long time, there is still an important lack of knowledge to explain plant tolerance or sensitivity towards ammonium nutrition. In this context, we performed a comparative proteomic study in roots of Arabidopsis thaliana plants grown under exclusive ammonium or nitrate supply. We identified and quantified 68 proteins with differential abundance between both conditions. These proteins revealed new potential important players on root response to ammonium nutrition, such as H⁺-consuming metabolic pathways to regulate pH homeostasis and specific secondary metabolic pathways like brassinosteroid and glucosinolate biosynthetic pathways.