Reduction in the Use of Some Herbicides Favors Nitrogen Fixation Efficiency in Phaseolus vulgaris and Medicago sativa

In recent decades, the quality of agricultural soils has been seriously affected by the excessive application of pesticides, with herbicides being one of the most abundant. Continuous use of herbicides alters the soil microbial community and beneficial interactions between plants and bacteria such as legume-rhizobia spp. symbiosis, causing a decrease in the biological nitrogen fixation, which is essential for soil fertility. Therefore, the aim of this work was to study the effect of two commonly used herbicides (pendimethalin and clethodim) on the legume-rhizobia spp. symbiosis to improve the effectiveness of this process. Phaseolus vulgaris plants grown in pots with a mixture of soil:perlite (3:1 v/v), showed a 44% inhibition of nitrogen fixation rate with pendimethalin. However, clethodim, specifically used against monocots, did not induce significant differences. Additionally, we analyzed the effect of herbicides on root exudate composition, detecting alterations that might be interfering with the symbiosis establishment. In order to assess the effect of the herbicides at the early nodulation steps, nodulation kinetics in Medicago sativa plants inoculated with Sinorhizobium meliloti were performed. Clethodim caused a 30% reduction in nodulation while pendimethalin totally inhibited nodulation, producing a reduction in bacterial growth and motility as well. In conclusion, pendimethalin and clethodim application reduced the capacity of Phaseolus vulgaris and Medicago sativa to fix nitrogen by inhibiting root growth and modifying root exudate composition as well as bacterial fitness. Thus, a reduction in the use of these herbicides in these crops should be addressed to favor a state of natural fertilization of the soil through greater efficiency of leguminous crops.

The Lack of Alternative Oxidase 1a Restricts in vivo Respiratory Activity and Stress-Related Metabolism for Leaf Osmoprotection and Redox Balancing Under Sudden Acute Water and Salt Stress in Arabidopsis thaliana

In plants salt and water stress result in an induction of respiration and accumulation of stress-related metabolites (SRMs) with osmoregulation and osmoprotection functions that benefit photosynthesis. The synthesis of SRMs may depend on an active respiratory metabolism, which can be restricted under stress by the inhibition of the cytochrome oxidase pathway (COP), thus causing an increase in the reduction level of the ubiquinone pool. However, the activity of the alternative oxidase pathway (AOP) is thought to prevent this from occurring while at the same time, dissipates excess of reducing power from the chloroplast and thereby improves photosynthetic performance. The present research is based on the hypothesis that the accumulation of SRMs under osmotic stress will be affected by changes in folial AOP activity. To test this, the oxygen isotope-fractionation technique was used to study the in vivo respiratory activities of COP and AOP in leaves of wild-type Arabidopsis thaliana plants and of aox1a mutants under sudden acute stress conditions induced by mannitol and salt treatments. Levels of leaf primary metabolites and transcripts of respiratory-related proteins were also determined in parallel to photosynthetic analyses. The lack of in vivo AOP response in the aox1a mutants coincided with a lower leaf relative water content and a decreased accumulation of crucial osmoregulators. Additionally, levels of oxidative stress-related metabolites and transcripts encoding alternative respiratory components were increased. Coordinated changes in metabolite levels, respiratory activities and photosynthetic performance highlight the contribution of the AOP in providing flexibility to carbon metabolism for the accumulation of SRMs.

Arbuscular mycorrhizal fungi from acidic soils favors production of tomatoes and lycopene concentration

BACKGROUND

Tomato is widely consumed throughout the world for its flavor and nutritional value. This functional food largely depends on the implementation of new strategies to maintain the nutraceutical value, e.g. lycopene concentration, and overcome the challenges of sustainable production and food security. The use of arbuscular mycorrhizal fungi (AMF)-based biostimulants represents one of the most promising tools for sustainable management of agricultural soils, being fundamental for organic food production, reducing fertilizers and pesticides use, and decreasing environmental damage. This study aimed at elucidating whether native arbuscular mycorrhizal fungi (AMF) could positively affect tomato yield and lycopene concentration.

RESULTS

Native AMF inoculum consisted of two inoculum types: the single species Claroideoglomus claroideum, and a mix of Scutellospora calospora, Acaulospora laevis, Claroideoglomus claroideum, and Claroideoglomus etunicatum. At the end of the study up to 78% of the root system was colonized by single inoculum. Tomato diameters in single and mix mycorrhizal plants showed increases of 80% and 35% respectively. Fresh weights were 84% and 38% higher with single and mix inocula compared with the controls, respectively. The lycopene concentration in tomato fruits of plants with single and mix inoculum was higher than controls. The lycopene concentration was 124.5% and 113.9% greater in single and mix than non-inoculated plants.

CONCLUSION

Tomato diameters, fresh weight and lycopene concentration was significantly higher in plants colonized by AMF compared with uninoculated plants. Results suggest that the role of single species Claroideoglomus claroideum could generate better plant performance due to its high production of extraradical mycelium. © 2021 Society of Chemical Industry.

Application of emerging technologies to obtain legume protein isolates with improved techno-functional properties and health effects

Current demand of consumers for healthy and sustainable food products has led the industry to search for different sources of plant protein isolates and concentrates. Legumes represent an excellent nonanimal protein source with high-protein content. Legume species are distributed in a wide range of ecological conditions, including regions with drought conditions, making them a sustainable crop in a context of global warming. However, their use as human food is limited by the presence of antinutritional factors, such as protease inhibitors, lectins, phytates, and alkaloids, which have adverse nutritional effects. Antitechnological factors, such as fiber, tannins, and lipids, can affect the purity and protein extraction yield. Although most are removed or reduced during alkaline solubilization and isoelectric precipitation processes, some remain in the resulting protein isolates. Selection of appropriate legume genotypes and different emerging and sustainable facilitating technologies, such as high-power ultrasound, pulsed electric fields, high hydrostatic pressure, microwave, and supercritical fluids, can be applied to increase the removal of unwanted compounds. Some technologies can be used to increase protein yield. The technologies can also modify protein structure to improve digestibility, reduce allergenicity, and tune technological properties. This review summarizes recent findings regarding the use of emerging technologies to obtain high-purity protein isolates and the effects on techno-functional properties and health.

Effect of cold stress on polyamine metabolism and antioxidant responses in chickpea

Metabolic and genomic characteristics of polyamines (PAs) may be associated with the induction of cold tolerance (CT) responses in plants. Characteristics of PAs encoding genes in chickpea (Cicer arietinum L.) and their function under cold stress (CS) are currently unknown. In this study, the potential role of PAs along with the antioxidative defense systems were assessed in two chickpea genotypes (Sel96th11439, cold-tolerant and ILC533, cold-sensitive) under CS conditions. Six days after exposure to CS, the leaf H₂O₂ content and electrolyte leakage index increased in the sensitive genotype by 47.7 and 59 %, respectively, while these values decreased or remained unchanged, respectively, in the tolerant genotype. In tolerant genotype, the enhanced activity of superoxide dismutase (SOD) (by 50 %) was accompanied by unchanged activities of ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) as well as the accumulation of glutathione (GSH) (by 43 %) on the sixth day of CS. Higher levels of putrescine (Put) (322 %), spermidine (Spd) (45 %), spermine (Spm) (69 %) and the highest ratio of Put/(Spd + Spm) were observed in tolerant genotype compared to the sensitive one on the sixth day of CS. Gamma-aminobutyric acid (GABA) accumulation was 74 % higher in tolerant genotype compared to the sensitive one on the sixth day of CS. During CS, the activity of diamine oxidase (DAO) and polyamine oxidase (PAO) increased in tolerant (by 3.02- and 2.46-fold) and sensitive (by 2.51- and 2.8-fold) genotypes, respectively, in comparison with the respective non-stressed plants (normal conditions). The highest activity of DAO and PAO in the tolerant genotype was accompanied by PAs decomposition and a peak in GABA content on the sixth day of CS. The analysis of chickpea genome revealed the presence of five PAs biosynthetic genes, their chromosomal locations, and cis-regulatory elements. A significant increase in transcript levels of arginine decarboxylase (ADC) (24.26- and 7.96-fold), spermidine synthase 1 (SPDS1) (3.03- and 1.53-fold), SPDS2 (5.5- and 1.62-fold) and spermine synthase (SPMS) (3.92- and 1.65-fold) genes was detected in tolerant and sensitive genotypes, respectively, whereas the expression of ornithine decarboxylase (ODC) genes decreased significantly under CS conditions in both genotypes. Leaf chlorophyll and carotenoid contents exhibited declining trends in the sensitive genotype, while these photosynthetic pigments were stable in the tolerant genotype due to the superior performance of defensive processes under CS conditions. Overall, these results suggested the specific roles of putative PAs genes and PAs metabolism in development of effective CT responses in chickpea.

In Vivo Metabolic Regulation of Alternative Oxidase under Nutrient Deficiency-Interaction with Arbuscular Mycorrhizal Fungi and Rhizobium Bacteria

The interaction of the alternative oxidase (AOX) pathway with nutrient metabolism is important for understanding how respiration modulates ATP synthesis and carbon economy in plants under nutrient deficiency. Although AOX activity reduces the energy yield of respiration, this enzymatic activity is upregulated under stress conditions to maintain the functioning of primary metabolism. The in vivo metabolic regulation of AOX activity by phosphorus (P) and nitrogen (N) and during plant symbioses with Arbuscular mycorrhizal fungi (AMF) and Rhizobium bacteria is still not fully understood. We highlight several findings and open questions concerning the in vivo regulation of AOX activity and its impact on plant metabolism during P deficiency and symbiosis with AMF. We also highlight the need for the identification of which metabolic regulatory factors of AOX activity are related to N availability and nitrogen-fixing legume-rhizobia symbiosis in order to improve our understanding of N assimilation and biological nitrogen fixation.

Overexpression of the arginine decarboxylase gene promotes the symbiotic interaction Medicago truncatula-Sinorhizobium meliloti and induces the accumulation of proline and spermine in nodules under salt stress conditions

Legumes have the capacity to fix nitrogen in symbiosis with soil bacteria known as rhizobia by the formation of root nodules. However, nitrogen fixation is highly sensitive to soil salinity with a concomitant reduction of the plant yield and soil fertilization. Polycationic aliphatic amines known as polyamines (PAs) have been shown to be involved in the response to a variety of stresses in plants including soil salinity. Therefore, the generation of transgenic plants overexpressing genes involved in PA biosynthesis have been proposed as a promising tool to improve salt stress tolerance in plants. In this work we tested whether the modulation of PAs in transgenic Medicago truncatula plants was advantageous for the symbiotic interaction with Sinorhizobium meliloti under salt stress conditions, when compared to wild type plants. Consequently, we characterized the symbiotic response to salt stress of the homozygous M. truncatula plant line L-108, constitutively expressing the oat adc gene, coding for the PA biosynthetic enzyme arginine decarboxylase, involved in PAs biosynthesis. In a nodulation kinetic assay, nodule number incremented in L-108 plants under salt stress. In addition, these plants at vegetative stage showed higher nitrogenase and nodule biomass and, under salt stress, accumulated proline (Pro) and spermine (Spm) in nodules, while in wt plants, the accumulation of glutamic acid (Glu), γ-amino butyric acid (GABA) and 1-aminocyclopropane carboxylic acid (ACC) (the ethylene (ET) precursor) were the metabolites involved in the salt stress response. Therefore, overexpression of oat adc gene favours the symbiotic interaction between plants of M. truncatula L-108 and S. meliloti under salt stress and the accumulation of Pro and Spm, seems to be the molecules involved in salt stress tolerance.

Restrictive water condition modifies the root exudates composition during peanut-PGPR interaction and conditions early events, reversing the negative effects on plant growth

Water deficit is one of the most serious environmental factors that affect the productivity of crops in the world. Arachis hypogaea is a legume with a high nutritional value and 70% is cultivated in semi-arid regions. This research aimed to study the effect of water deficit on peanut root exudates composition, analyzing the importance of exudates on peanut-PGPR interaction under restrictive water condition. Peanut seedlings were subjected to six treatments: 0 and 15 mM PEG, in combination with non-inoculated, Bradyrhizobium sp. and Bradyrhizobium-Azospirillum brasilense inoculated treatments. We analyzed the 7-day peanut root exudate in response to a water restrictive condition and the presence of bacterial inocula. Molecular analysis was performed by HPLC, UPLC and GC. Bacteria motility, chemotaxis, bacterial adhesion to peanut roots and peanut growth parameters were analyzed. Restrictive water condition modified the pattern of molecules exuded by roots, increasing the exudation of Naringenin, oleic FA, citric and lactic acid, and stimulation the release of terpenes of known antioxidant and antimicrobial activity. The presence of microorganisms modified the composition of root exudates. Water deficit affected the first events of peanut-PGPR interaction and the root exudates favored bacterial mobility, the chemotaxis and attachment of bacteria to peanut roots. Changes in the profile of molecules exuded by roots allowed A. hypogaea-Bradyrhizobium and A.hypogaea-Bradyrhizobium-Azospirillum interaction thus reversing the negative effects of restrictive water condition on peanut growth. These findings have a future potential application to improve plant-PGPR interactions under water deficit by formulating inoculants containing key molecules exuded during stress.

Polyamines contribute to salinity tolerance in the symbiosis Medicago truncatula-Sinorhizobium meliloti by preventing oxidative damage

Polyamines (PAs) such as spermidine (Spd) and spermine (Spm) are small ubiquitous polycationic compounds that contribute to plant adaptation to salt stress. The positive effect of PAs has been associated to a cross-talk with other anti-stress hormones such as brassinosteroids (BRs). In this work we have studied the effects of exogenous Spd and Spm pre-treatments in the response to salt stress of the symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti by analyzing parameters related to nitrogen fixation, oxidative damage and cross-talk with BRs in the response to salinity. Exogenous PAs treatments incremented the foliar and nodular Spd and Spm content which correlated with an increment of the nodule biomass and nitrogenase activity. Exogenous Spm treatment partially prevented proline accumulation which suggests that this polyamine could replace the role of this amino acid in the salt stress response. Additionally, Spd and Spm pre-treatments reduced the levels of H₂O₂ and lipid peroxidation under salt stress. PAs induced the expression of genes involved in BRs biosynthesis which support a cross-talk between PAs and BRs in the salt stress response of M. truncatula-S. meliloti symbiosis. In conclusion, exogenous PAs improved the response to salinity of the M. truncatula-S. meliloti symbiosis by reducing the oxidative damage induced under salt stress conditions. In addition, in this work we provide evidences of the cross-talk between PAs and BRs in the adaptive responses to salinity.

24-Epibrassinolide ameliorates salt stress effects in the symbiosis Medicago truncatula-Sinorhizobium meliloti and regulates the nodulation in cross-talk with polyamines

Brassinosteroids (BRs) are steroid plant hormones that have been shown to be involved in the response to salt stress in cross-talk with other plant growth regulators such as polyamines (PAs). In addition, BRs are involved in the regulation of the nodulation in the rhizobium-legume symbiosis through the alteration of the PAs content in leaves. In this work, we have studied the effect of exogenous 24-epibrassinolide (EBL) in the response to salinity of nitrogen fixation in the symbiosis Medicago truncatula-Sinorhizobium meliloti. Foliar spraying of EBL restored the growth of plants subjected to salt stress and provoked an increment of the nitrogenase activity. In general, PAs levels in leaves and nodules decreased by the salt and EBL treatments, however, the co-treatment with NaCl and EBL augmented the foliar spermine (Spm) concentration. This increment of the Spm levels was followed by a reduction of the membrane oxidative damage and a diminution of the proline accumulation. The effect of BRs on the symbiotic interaction was evaluated by the addition of 0.01, 0.1 and 0.5 μM EBL to the growing solution, which provoked a reduction of the nodule number and an increment of the PAs levels in shoot. In conclusion, foliar treatment with EBL had a protective effect against salt stress in the M. truncatula-S. meliloti symbiosis mediated by an increment of the Spm levels. Treatment of roots with EBL incremented PAs levels in shoot and reduced the nodule number which suggests a cross-talk between PAs and BRs in the nodule suppression and the protection against salt stress.

Arabidopsis thaliana polyamine content is modified by the interaction with different Trichoderma species

Plants are associated with a wide range of microorganisms throughout their life cycle, and some interactions result on plant benefits. Trichoderma species are plant beneficial fungi that enhance plant growth and development, contribute to plant nutrition and induce defense responses. Nevertheless, the molecules involved in these beneficial effects still need to be identify. Polyamines are ubiquitous molecules implicated in plant growth and development, and in the establishment of plant microbe interactions. In this study, we assessed the polyamine profile in Arabidopsis plants during the interaction with Trichoderma virens and Trichoderma atroviride, using a system that allows direct plant-fungal contact or avoids their physical interaction (split system). The plantlets that grew in the split system exhibited higher biomass than the ones in direct contact with Trichoderma species. After 3 days of interaction, a significant decrease in Arabidopsis polyamine levels was observed in both systems (direct contact and split). After 5 days of interaction polyamine levels were increased. The highest levels were observed with T. atroviride (split system), and with T. virens (direct contact). The expression levels of Arabidopsis ADC1 and ADC2 genes during the interaction with the fungi were also assessed. We observed a time dependent regulation of ADC1 and ADC2 genes, which correlates with polyamine levels. Our data show an evident change in polyamine profile during Arabidopsis - Trichoderma interaction, accompanied by evident alterations in plant root architecture. Polyamines could be involved in the changes undergone by plant during the interaction with this beneficial fungus.

Occurrence of polyamines in root nodules of Phaseolus vulgaris in symbiosis with Rhizobium tropici in response to salt stress

Polyamines (PAs) are low molecular weight aliphatic compounds that have been shown to be an important part of plant responses to salt stress. For that reason in this work we have investigated the involvement of PAs in the response to salt stress in root nodules of Phaseolus vulgaris in symbiosis with Rhizobium tropici. The level and variety of PAs was higher in nodules, compared to leaves and roots, and in addition to the common PAs (putrescine, spermidine and spermine) we found homospermidine (Homspd) as the most abundant polyamine in nodules. UPLC-mass spectrometry analysis revealed the presence of 4-aminobutylcadaverine (4-ABcad), only described in nodules of Vigna angularis before. Indeed, the analysis of different nodular fractions revealed higher level of 4-ABcad, as well as Homspd, in bacteroids which indicate the production of these PAs by the bacteria in symbiosis. The genes involved in PAs biosynthesis in nodules displayed an induction under salt stress conditions which was not consistent with the decline of free PAs levels, probably due to the nitrogen limitations provoked by the nitrogenase activity depletion and/or the conversion of free PAs to theirs soluble conjugated forms, that seems to be one of the mechanisms involved in the regulation of PAs levels. On the contrary, cadaverine (Cad) and 4-ABcad concentrations augmented by the salinity, which might be due to their involvement in the response of bacteroids to hyper-osmotic conditions. In conclusion, the results shown in this work suggest the alteration of the bacteroidal metabolism towards the production of uncommon PAs such as 4-ABcad in the response to salt stress in legume root nodules.

Involvement of abscisic acid in the response of Medicago sativa plants in symbiosis with Sinorhizobium meliloti to salinity

Legumes are classified as salt-sensitive crops with their productivity particularly affected by salinity. Abcisic acid (ABA) plays an important role in the response to environmental stresses as signal molecule which led us to study its role in the response of nitrogen fixation and antioxidant metabolism in root nodules of Medicago sativa under salt stress conditions. Adult plants inoculated with Sinorhizobium meliloti were treated with 1 μM and 10 μM ABA two days before 200 mM salt addition. Exogenous ABA together with the salt treatment provoked a strong induction of the ABA content in the nodular tissue which alleviated the inhibition induced by salinity in the plant growth and nitrogen fixation. Antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) were induced by ABA pre-treatments under salt stress conditions which together with the reduction of the lipid peroxidation, suggest a role for ABA as signal molecule in the activation of the nodular antioxidant metabolism. Interaction between ABA and polyamines (PAs), described as anti-stress molecules, was studied being detected an induction of the common polyamines spermidine (Spd) and spermine (Spm) levels by ABA under salt stress conditions. In conclusion, ABA pre-treatment improved the nitrogen fixation capacity under salt stress conditions by the induction of the nodular antioxidant defenses which may be mediated by the common PAs Spd and Spm that seems to be involved in the anti-stress response induced by ABA.

Salicylic acid improves the salinity tolerance of Medicago sativa in symbiosis with Sinorhizobium meliloti by preventing nitrogen fixation inhibition

In this work we have investigated the contribution of pretreatment with 0.1 and 0.5mM salicylic acid (SA) to the protection against salt stress in root nodules of Medicago sativa in symbiosis with Sinorhizobium meliloti. SA alleviated the inhibition induced by salinity in the plant growth and photosynthetic capacity of M. sativa-S. meliloti symbiosis. In addition, SA prevented the inhibition of the nitrogen fixation capacity under salt stress since nodule biomass was not affected by salinity in SA pretreated plants. Antioxidant enzymes peroxidase (POX), superoxide dismutase (SOD), ascorbate peroxidase (APX), dehidroascorbate reductase (DHAR) and glutathione reductase (GR), key in the main pathway that scavenges H2O2 in plants, were induced by SA pretreatments which suggest that SA may participate in the redox balance in root nodules under salt stress. Catalase activity (CAT) was inhibited around 40% by SA which could be behind the increase of H2O2 detected in nodules of plants pretreated with SA. The accumulation of polyamines (PAs) synthesized in response to salinity was prevented by SA which together with the induction of 1-aminocyclopropane-l-carboxylic acid (ACC) content suggest the prevalence of the ethylene signaling pathway induced by SA in detriment of the synthesis of PAs. In conclusion, SA alleviated the negative effect of salt stress in the M. sativa-S. meliloti symbiosis through the increased level of nodule biomass and the induction of the nodular antioxidant metabolism under salt stress. The H2O2 accumulation and the PAs inhibition induced by SA in nodules of M. sativa suggest that SA activates a hypersensitive response dependent on ethylene.

Analysis of the concordance in the EGFR pathway status between primary tumors and related metastases of colorectal cancer patients:implications for cancer therapy

Patients with metastatic Colorectal Cancer (mCRC), in which primary tumors are KRAS mutated, have no response to anti-EGFR therapy. However, less than half of mCRC patients with KRAS wild-type primary tumors respond to anti-EGFR therapy. Other downstream effectors of the EGFR pathway are being analyzed to fine-tune KRAS predictive value. However, as the primary tumor is the tissue of analysis that determines the use of anti-EGFR therapy in advanced disease, a high concordance in the status of these effectors between primary tumors and related metastases is required. We analyzed the concordances of downstream EGFR effectors in tumoral pairs of primaries and related metastases in a series of KRAS wild-type patients. One hundred seventeen tumoral pairs from patients with CRC were tested for KRAS mutational status. The level of concordance in the presence of KRAS mutations was 91% between the primary tumor and related metastases. The 70 pairs with KRAS wild-type primary tumors were further analyzed for BRAF and PIK3CA mutational status and for EGFR, PTEN and pAKT expression, and the number of concordant pairs was 70 (100%), 66 (94%), 43 (61%), 46 (66%) and 36 (54%), respectively. Our findings suggest that the mutational status of KRAS, BRAF and PIK3CA in the primary tumor is an adequate surrogate marker of the status in the metastatic disease. On the other hand, the immunohistochemical analysis of EGFR, PTEN and pAKT showed a much higher degree of discordance between primaries and related metastases.

Concordance of K-Ras status between colorectal cancer (CRC) primaries and related metastatic samples considering clinicopathological features

4053

Background: K-Ras mutations in CRC primaries may predict resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies, but we don´t know its behaviour in metastatic tissue. The aims of this study were: 1) Evaluate the grade of concordance of K-Ras status between primary and related metastatic samples 2) Establish a correlation between k-ras status and individual clinicopathological features Methods: K-ras mutations were retrospectively analysed in primary tumours of 124 patients and 138 related metastatic sites. The primary tumour site was colon in 87 patients and rectum in 37. Sites of metastases were liver (115 samples,83.3%) and lung (23 samples,16.7%). Some patients underwent surgery several times. We analyzed K-Ras point mutations in codons 12 and 13 by direct DNA sequencing from paraffin-embedded tumour and studied its relation with 13 clinicopathological features Results: K-Ras mutation was observed in 42(33.6%) primary tumours and in 52(39.1%) related metastatic sites, being the grade of concordance between primary and metastatic sites of 93% (95% CI: 97.5–88.3%). Discordance was observed in 9 (7%) patients: in 2, K-Ras status was wild type in metastatic site and expressed a mutational pattern in the primary tumour; vice versa, in 7, the mutation status was detected in the metastases meanwhile primary tumour was wild type. We also found statistically significative differences in mutation patterns regarding the site of the metastasic tissue: K-ras mutations were detected in 13 lung samples (61.9%) and in 39 liver samples (34.8%) (p=0.028). Of all the clinicopathological features analyzed we confirmed an increase of mutated K-ras status in tumours which had presented as perforation (p=0.044). No other relation with clinicopathological data was detected Conclusions: With this observational analysis, we confirm the high concordance (superior to 90%) between primary and related metastatic sites in terms of K-Ras status; for the first time, we have reported a higher mutational pattern in lung metastases than in liver disease, founds that may have important relevance regarding clinical/treatment decisions. For the realization of this study we received a grant from Amgen.

No significant financial relationships to disclose.

Clinical presentation of anxiety among patients with epilepsy

Different factors have been related with interictal anxiety, reported in 10%-25% of patients with epilepsy. We determined the frequency of interictal anxiety in 196 patients with active epilepsy in a cross-sectional survey to know which symptoms of anxiety were most frequently reported in patients with epilepsy and to analyze the factors associated with their presence. Patients were assessed with the Beck Depression Inventory (BDI), Montgomery-Asberg Depression Rating Scale (MADRS), and the Hamilton Anxiety Scale (HAMA). Data were analyzed with a logistic regression model. The HAMA ratings revealed that 38.8% experienced significant anxiety symptoms, as defined by a rating above 18 points. Use of primidone, depression, cryptogenic, and posttraumatic etiologies significantly predicted anxiety after logistic regression. Symptoms related to higher scores on HAMA were anxious mood, tension, insomnia, intellectual function, depressed mood, cardiovascular and genitourinary symptoms. Further studies should be performed to define the role of psychosocial factors in the development and evolution of anxiety among these patients.

Sleep disturbances, socioeconomic status, and seizure control as main predictors of quality of life in epilepsy

Improving quality of life is the most important goal for patients with epilepsy. To recognize the factors associated with quality of life in patients with epilepsy in Mexico, we performed a cross-sectional survey using the Quality of Life in Epilepsy 31 (QOLIE-31) inventory to assess the quality of life of 401 adult patients with epilepsy at the National Institute of Neurology and Neurosurgery of Mexico. Clinical and demographical data were collected. Multiple regression was used to determine which factors affected quality of life in our patients. The variables that most strongly predicted a lower QOLIE-31 total score after multiple regression were sleep disorders (P<0.001), socioeconomic status (P<0.001), female gender (P=0.002), and high seizure frequency (P=0.001). In our study, neither depression nor time of evolution of epilepsy had significant influence on QOLIE-31 scores.

[Frequency of neuropsychiatric signs and symptoms in patients with viral encephalitis]

INTRODUCTION

Acute viral encephalitis (AVE) is a frequent condition that usually courses with psychiatric alterations but few systematic studies have been conducted to investigate it.

AIMS

To determine the frequency and the progression of the neuropsychiatric symptoms in patients with AVE.

PATIENTS AND METHODS

A retrospective study was carried out. AVE was defined as an acute and progressively coursing condition in previously healthy subjects, with clinical signs of diffuse alteration of the central nervous system, abnormal electroencephalogram and/or inflammatory cerebrospinal fluid (CSF). We excluded patients who previously had epilepsy, a positive serodiagnosis for human immunodeficiency virus (HIV), and cases compatible with herpes simplex encephalitis from electroencephalographic or imaging data with focalisation towards temporal, frontal, regions or a positive DNA test for herpes in CSF. Finally, 83 patients were included. The psychiatric signs and symptoms that were produced were recorded during the acute phase and one year after discharge from hospital (sequelae).

RESULTS

The psychiatric disorders in the acute phase were psychomotor agitation (67%), drowsiness (55%), disorientation (47%), visual hallucinations (43%) and aggressiveness (34%). One year after hospitalisation, in a sample of 70 patients in a clinical control, we found memory disorders (16%), aggressiveness (9%), aphasia (8%), visual hallucinations (8%), and auditory hallucinations (7%). The mortality rate was 6%.

CONCLUSIONS

Neuropsychiatric disorders are very frequent during the acute phase of viral encephalitis, which is relevant for the differential diagnosis in patients who visit emergency departments with behavioural disorders. One year after hospital discharge, the main sequelae are of a neuropsychiatric nature and cognitive impairment is predominant.

[Non-valvular atrial fibrillation and completed stroke: factors determining mortality, recurrence and prognosis after a first event in the Mexican population]

AIMS

Non-valvular atrial fibrillation (NVAF) accounts for 25% of completed strokes (CS) of a cardioembolic origin in patients over 60 years old. Our aim was to define the predictors of a good and poor prognosis after a CS secondary to an NVAF in our milieu.

PATIENTS AND METHODS

We evaluated the risk factors (RF) and severity of CS in relation to death, functionality and recurrence at 5 years. 81 patients between the ages of 49 and 88 were followed up consecutively for 1 to 90 months; 38 (46.9%) of them were males. Multivariate analysis was performed with the following independent variables: age, gender, smoking, hypertension, heart disease, diabetes mellitus and characteristics of the stroke. The severity of the CS was assessed by means of the modified Rankin scale, which was dichotomised into a good prognosis (0-2) and a poor prognosis (> or = 3), both basal and at the end of the clinical control. We also evaluated the secondary preventive treatment used and its relation with recurrence, prognosis, death and complications.

RESULTS

No RF was linked to a poor prognosis or recurrence; 88% had a poor prognosis. Antiplatelet drugs were used in 42% of cases and 39% received anticoagulants. A good final progression was observed in 9.5% of the patients treated with antiplatelet drugs versus 35% of those receiving anticoagulation therapy (p = 0.004). Severity of the CS on admission was worse in the aspirin group, with no differences in recurrence and mortality. A better prognosis was observed in patients from urban areas.

CONCLUSIONS

Use of antiplatelet drugs, living in a rural area and a Rankin score of > or = 3 on admission are factors suggesting a poor prognosis in the clinical control at 5 years.

Nontyphoidal salmonella intracranial infections in HIV-infected patients

Salmonella focal intracranial infections are unusual in human immunodeficiency virus (HIV)-infected patients. Six such infections have been reported in the world literature. We report a case of salmonella subdural and epidural cerebral empyema with concomitant osteomyelitis of the frontal bone. Such a complication in the course of salmonellosis is reported for the first time. In previously published case reports, four patients had brain abscess and two had subdural empyema. Salmonella typhimurium was isolated from two patients, and different serotypes were recovered from the others. All patients had advanced HIV disease, and all but two had had opportunistic infections before the diagnosis of salmonella intracranial infection. Surgical drainage combined with systemic antibiotic therapy resulted in the recovery of four of five patients. No regression of the lesions occurred in one patient treated only with antibiotics for multiple cerebral abscesses.

[Proliferation of large granular lymphocytes in patients with systemic lupus erythematosus]

BACKGROUND

Large granular T lymphocytes (LGL) make up a small portion of cellular population in peripheral blood. An abnormal proliferation of LGL is detected together with cytopenic and other autoimmune disorders and is often associated with rheumatoid arthritis. The association with other autoimmune diseases, such as systemic lupus erythematosus, is poorly known. The clinical and immunological profile in five patients with SLE and LGL proliferation is here reported.

MATERIALS AND METHODS

A clinical follow-up and prospective phenotypic study of mononuclear cells was conducted in patients with SLE for a period of 24 months. LGL were identified on the basis of their shape and analyzed by flow cytometry as cells coexpressing thymic differentiation antigens (CD3 and CD4, or CD8) and NK cells CD16, CD56 or CD57).

RESULTS

Five out of 43 patients with SLE showed recurrent proliferations of LGL (from 2 to 4 per patient) chronologically associated with lupus exacerbations. LGL represented 52 to 78% (mean +/- SD = 56 +/- 8%) from the total of lymphocytes. The phenotype in proliferations was heterogeneous but it was consistent in later relapses in each patient (patient #1 and #2: CD3+CD8-CD4+CD16+CD56+CD57-HLA/D+ patients #3 and #4: CD3+CD8+CD4-CD16+CD56+CD57-HLA/DR+ patient #5: CD3+CD8+CD4- CD16+CD56+CD57-HLA/DR+patient 5:CD3+CD8+CD4-CD16 +/- CD56-CD57+HLA/DR+). These five patients had long term SLE with a greater number of exacerbations and a tendency to develop hemocytopenias, requiring high doses of corticosteroids and even immunosuppressors to control their condition.

CONCLUSIONS

Some patients with SLE develop LGL proliferations. The activity, clinical severity and hematological involvement seem to be associated with this immunological disorder, but the pathogenic significance and prognosis of these proliferations are still to be elucidated.

CD5+ B lymphocytes in HIV infection: relationship to immunological progression of disease

We analyzed CD5+ B cells in HIV-seropositive individuals because there is accumulating evidence of the involvement of this subset in natural immunity against virus and bacteria. There are also arguments maintaining that CD5+ B cells play a role in autoimmunity and lymphoid malignancies, both phenomena which are strongly associated with HIV infection. Seventy-two HIV-positive subjects (58 drug abusers, 7 homosexual men, 4 heterosexuals, and 3 hemophiliacs) were included in a phenotypic study of mononuclear cells. A direct immunofluorescence with doubly conjugated monoclonal antibodies was performed, and analysis was carried out in a FACScan cytometer. HIV-infected patients showed a striking increase in the percentage of CD5+ B lymphocytes (54.7 +/- 19% of circulating B cells) compared with HIV-negative drug users (35.5 + 14%) and with healthy controls (17 +/- 5%), P < 0.01 and P < 0.0001, respectively. In addition, levels of CD5+ B cells were correlated with CD4+ cell counts (r = -0.50373), WR staging (r = 0.5295), lymphocytopenia (r = 0.57356), and T4/T8 ratio (r = -0.3151) and showed a close association with the progression of immune system damage by HIV. Patients who developed hypergammaglobulinemia, thrombocytopenia, or other autoimmune manifestations associated with HIV infection showed levels of CD5+ B cells increased over those of the remaining HIV-seropositive individuals (P < 0.001, P < 0.001, and P < 0.05).

[Listeria monocytogenes infection in HIV patients: 2 new cases]

Two new cases of infection due to Listeria monocytogenes in two females with HIV are discussed, one of them with full blown AIDS and the other pregnant and without knowledge of her seropositivity until that moment. Its clinical manifestation as a meningeal manifestation and bacteremia, coincide with the few cases described until now; different hypothesis invoked until now are reviewed to justify this infrequent association HIV-Listeria.