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C Vargas

Publications and source records attributed to C Vargas.

At least 19 recordsLinked to original sources
PubMed2007

Members of the ethylene signalling pathway are regulated in sugarcane during the association with nitrogen-fixing endophytic bacteria.

Nitrogen-fixing bacteria have been isolated from sugarcane in an endophytic and beneficial interaction that promotes plant growth. In this work, for the first time, the involvement of ethylene signalling in this interaction was investigated by molecular characterizing members of this pathway in sugarcane. The expression pattern of a putative ethylene receptor (SCER1) and two putative ERF transcription factors (SCERF1 and SCERF2) show exclusive modulation in plants inoculated with the diazotrophic endophytes. The gene expression profile of SCER1, SCERF1, and SCERF2 is differentially regulated in sugarcane genotypes that can establish efficient or inefficient associations with diazotrophic micro-organisms, exhibiting high or low biological nitrogen fixation (BNF) rates, respectively. In addition, SCER1, SCERF1, and SCERF2 expression is different in response to interactions with pathogenic and beneficial micro-organisms. Taken together, that data suggest that SCER1, SCERF1, and SCERF2 might participate in specific ethylene signalling cascade(s) that can identify a beneficial endophytic association, modulating sugarcane responses toward the diazotrophic endophytes.

Amino Acid Sequence↗
PubMed2006

High-dose radiation employing external beam radiotherapy and high-dose rate brachytherapy with and without neoadjuvant androgen deprivation for prostate cancer patients with intermediate- and high-risk features.

The role of neoadjuvant androgen deprivation (NAD) in high-risk prostate cancer patients receiving high-dose radiotherapy (RT) remains unstudied. To evaluate the effect of a course of NAD, we reviewed the experiences of three institutions treating these patients with combined RT and high-dose rate brachytherapy (HDR). Of 1260 prostate cancer patients with high-risk features (pretreatment prostate-specific antigen (PSA) > or =10, Gleason Score (GS) > or =7, or T stage > or =T2b), 560 received no NAD (n=308) or NAD for < or =6 months (n=252). Median dose to the prostate from RT and HDR was 42 and 23 Gy, respectively. Average total biologic equivalent prostate dose was >100 Gy (alpha/beta=1.2). Median follow-up was 4.3 years. Pretreatment characteristics were similar on chi(2) tables for all 560 patients treated with or without NAD including pretreatment PSA (P=0.11), GS (P=0.4), and clinical T stage (P=0.2). Outcomes worsened for patients receiving NAD (5-year distant metastasis (DM) 10 vs 5% (P=0.04); cause-specific survival (CSS), 93 vs 98% (P=0.005)). Higher 5-year DM rates and lower CSS occurred in NAD patients with a GS between 8 and 10 (n=112 (P=0.03, P=0.02)), pretreatment PSA> or =15 (n=136 (P=0.03, P=0.008)), and palpable disease > or =T2a (n=434 (P=0.04, P=0.02)). The only two significant risk factors for DM on Cox multivariate analysis were GS (P=0.003, HR 2.8) and NAD (P=0.03, HR 2.7). AD given before definitive high-dose RT did not benefit prostate cancer patients with intermediate- and high-risk features. We favor the use of concurrent/adjuvant AD over prolonged NAD for prostate cancer patients for whom AD is clinically indicated.

Aged↗
PubMed2006

SHR5: a novel plant receptor kinase involved in plant-N2-fixing endophytic bacteria association.

Endophytic nitrogen-fixing bacteria have been isolated from graminaceous plants such as maize, rice, and sugarcane. They are thought to promote plant growth, not only by fixing nitrogen, but also by the production of plant hormones. The molecular mechanisms involved in this interaction are not yet clear. In this work, the identification of a receptor-like kinase (RLK), named SHR5, which may participate in signal transduction involved in the establishment of plant-endophytic bacteria interaction is described for the first time. SHR5 seems to be part of a novel subclass of RLKs present in a wide range of plant species. The expression of this gene is down-regulated in sugarcane plants associated exclusively with beneficial endophytic bacteria and is not a general response caused by micro-organisms or abiotic stress. In addition, more successful sugarcane-endophytic bacteria associations have a more pronounced decrease in SHR5 expression, suggesting that SHR5 mRNA levels in plant cells are inversely related to the efficiency of the association.

Actinobacteria↗
PubMed2006

Ectoines as compatible solutes and carbon and energy sources for the halophilic bacterium Chromohalobacter salexigens.

AIMS: To investigate the catabolism of ectoine and hydroxyectoine, which are the major compatible solutes synthesized by Chromohalobacter salexigens. METHODS AND RESULTS: Growth curves performed in M63 minimal medium with low (0.75 mol l(-1) NaCl), optimal (1.5 mol l(-1) NaCl) or high (2.5 mol l(-1) NaCl) salinity revealed that betaine and ectoines were used as substrate for growth at optimal and high salt. Ectoine transport was maximal at optimal salinity, and showed 3- and 1.5-fold lower values at low and high salinity respectively. The salt-sensitive ectA mutant CHR62 showed an ectoine transport rate 6.8-fold higher than that of the wild type. Incubation of C. salexigens in a mixture of glucose and ectoine resulted in a biphasic growth pattern. However, CO(2) production due to ectoine catabolism was lower, but not completely abolished, in the presence of glucose. When used as the sole carbon source, glycine betaine effectively inhibited ectoine and hydroxyectoine synthesis at any salinity. CONCLUSIONS: The catabolic pathways for ectoine and hydroxyectoine in C. salexigens operate at optimal and high (although less efficiently) salinity. Endogenous ectoine(s) may repress its own transport. Ectoine utilization was only partially repressed by glucose. Betaine, when used as carbon source, suppresses synthesis of ectoines even under high osmolarity conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is a previous step to the subsequent isolation and manipulation of the catabolic genes, so as to generate strains with enhanced production of ectoine and hydroxyectoine.

Amino Acids, Diamino↗
PubMed2004

Neurotransmitter amino acid in cerebrospinal fluid of patients with dementia with Lewy bodies.

The purpose of the present study was to compare neurotransmitter amino acid concentrations in the cerebrospinal fluid (CSF) and CSF/plasma ratios in 21 patients with dementia with Lewy bodies (DLB) and 26 matched controls. To this purpose, we used an ion-exchange chromatographic method. DLB patients exhibit higher CSF concentrations of asparagine (+25%) and glycine (+21%) compared to a control group, whereas no differences in CSF/plasma ratios were found between both groups. On the other hand, no alterations in concentrations of glutamate, aspartate and GABA were detected in CSF of patients compared to a control group. There was no correlation among amino acid levels and CSF/plasma ratios with age, age of onset, body mass index, duration of the disease or scores of the Mini Mental State Examination, UPDRS and Hoehn and Yahr stage. These results suggest a possible role of glycine and asparagine in the pathogenic mechanism of dementia with Lewy bodies.

Age Factors↗
PubMed2003

[Vibrio vulnificus septicemia transmitted through a wound caused by a crustacea].

INTRODUCTION: Vibrio vulnificus proliferates during the summer in salt water where it infects the crustaceans. Expression of its pathogenicity depends on the underlying condition and mode of contamination. OBSERVATION: A 65 year-old man presented with a Vibrio vulnificus septicaemia of cutaneous origin, transmitted when he cut himself with a crawfish. The severity of the infection was enhanced by severe immuno-depression and haemochromatosis. The infection regressed with appropriate antibiotherapy. COMMENTS: Severe V. vulnificus infections are rare. Depending on the underlying condition and mode of contamination, one can distinguish between benign gastro-enteritis, local occasionally devastating infections and usually fatal septicaemia. CONCLUSION: Even the most severe forms of V. vulnificus infections may be cured with early and well adapted anti-infectious treatment.

Aged↗
PubMed2002

Cerebrospinal fluid levels of insulin in patients with Alzheimer's disease.

OBJECTIVES: Some previous reports suggested a potential role of insulin in memory and in the pathophysiology of Alzheimer's disease (AD). We assessed the cerebrospinal fluid (CSF) levels of insulin in patients with AD and in age and sex-matched controls trying to elucidate whether this value could be related with the risk or severity of AD. PATIENTS AND METHODS: We measured the CSF insulin levels in 27 patients with AD and 16 matched controls using a RadioImmunoanalysis method. RESULTS: CSF insulin levels did not differ significantly between AD-patient and control groups. These values were not correlated with age, age at onset, duration of the disease, and scores of the MiniMental State Examination in the AD group. CONCLUSION: These results suggest that CSF insulin concentrations are not related with the risk or severity of AD.

Age of Onset↗
PubMed2002

Predictive value of (99m)Tc sestamibi scintigraphy in the evaluation of doxorubicin based chemotherapy response in patients with advanced breast cancer.

Resistance to doxorubicin based chemotherapy is a major therapeutic problem limiting advanced breast cancer treatment. 99mTc hexakis-2-methoxyisobutylisonitrile ((99m)Tc-MIBI) has been reported to be extruded from tumour cells by the P-glycoprotein and multidrug resistance protein encoded by MDR1 and MRP1 genes, respectively. These proteins are involved in the cellular efflux of several chemotherapeutic agents including doxorubicin. The aim of this study was to investigate the clinical value of a standard (99m)Tc-MIBI scintimammography technique in the prediction of response to chemotherapy in advanced breast cancer patients. Fifty-six lesions from 33 female patients with locally advanced (n=27) or recurrent breast cancer (n=6) were included in the study. MIBI scintigraphy was performed 2-8 days prior to chemotherapy (FAC regimen). Images were acquired 10 min and 1 h post-injection of 740-1110 MBq of (99m)Tc-MIBI. Tumour-to-normal background tissue uptake ratios were calculated on each lesion in the early (T/B(e)) and delayed phase of the study (T/B(d)). Both T/B(e) and T/B(d) ratios were significantly higher (P<0.0001) in responders (n=43) than nonresponders (n=13). Diagnostic values of (99m)Tc-MIBI in the prediction of chemotherapy response were evaluated using the arbitrary cut-off values of 1.5 for T/B(e) and 1.4 forT/B(d). Sensitivity, specificity, positive and negative predictive values were 88.4%, 92.3%, 97.4%, 70.6%; and 90.7%, 100.0%, 100.0%, 76.6%, for T/B(e) and T/B(d), respectively. We conclude that (99m)Tc-MIBI scintigraphy may be a clinically valuable tool for guiding chemotherapy in advanced breast cancer patients.

Adult↗
PubMed2001

Potential role of endogenous brain-derived neurotrophic factor in long-term neuronal reorganization of the superior colliculus after bilateral visual deprivation.

The role of the brain-derived neurotrophic factor (BDNF), the BDNF receptor (TrkB), and the glutamic acid decarboxylase (GAD67) after neonatal, bilateral nerve deafferentiation during postnatal development was investigated in the rat superior colliculus (SC). BDNF and GAD67 mRNA expression were significantly increased in optic (Op) and intermediate gray (InG) layers at 5, 8, 15, and 21 days after birth, but not in adult animals. However, TrkB mRNA expression was not modified at any time tested. At 15 days, where changes in BDNF and GAD67 mRNAs were more evident, an upregulation of the NMDAR(1A) mRNA glutamate receptor in the Op and InG, a modification in the pattern of synaptic zinc in the superficial layers of SC, and an increased synaptophysin immunoreactivity in the Op was found. This indicates the existence of a synergic mechanism between BDNF and NMDA to determine refinement of connections after the loss of visual input in SC.

Animals↗
PubMed2001

Anaerobic reductive dechlorination of chlorinated dioxins in estuarine sediments.

The biotransformation of 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-tetraCDD) under anaerobic sulfate-reducing, methanogenic, and iron-reducing conditions was examined with anaerobic enrichment cultures established with sediment from an estuarine intertidal strait in the New York/New Jersey harbor. In addition, the effect of prior enrichment on 2-bromophenol or a mixture of 2-, 3-, and 4-bromophenol on dioxin dechlorination was examined. All enrichments were spiked with 1 ppm 1,2,3,4-tetraCDD and monitored by gas chromatography-mass spectrometry for up to a 3-year period. Reductive dechlorination was initially observed only under methanogenic conditions in the cultures enriched on all three bromophenol isomers. 1,2,3,4-TetraCDD was dechlorinated in the lateral position to 1,2,4-triCDD. The initial appearance of 1,2,4-triCDD was observed after 2 months, with further dechlorination to 1,3-diCDD within 17 months.

Anaerobiosis↗
PubMed2001

Ontogeny and subcellular localization of rat liver mitochondrial branched chain amino-acid aminotransferase.

Branched chain amino-acid aminotransferase (BCAT) activity is present in fetal liver but the developmental pattern of mitochondrial BCAT (BCATm) expression in rat liver has not been studied. The aim of this study was to determine the activity, protein and mRNA concentration of BCATm in fetal and postnatal rat liver, and to localize this enzyme at the cellular and subcellular levels at both developmental stages. Maximal BCAT activity and BCATm mRNA expression occurred at 17 days' gestation in fetal rat liver and then declined significantly immediately after birth. This pattern was observed only in liver; rat heart showed a different developmental pattern. Fetal liver showed intense immunostaining to BCATm in the nuclei and mitochondria of hepatic cells and blood cell precursors; in contrast, adult liver showed mild immunoreactivity located only in the mitochondria of hepatocytes. BCAT activity in isolated fetal liver nuclei was 0.64 mU x mg(-1) protein whereas it was undetectable in adult liver nuclei. By Western blot analysis the BCATm antibody recognized a 41-kDa protein in fetal liver nuclei, and proteins of 41 and 43 kDa in fetal liver supernatant. In adult rat liver supernatant, the BCATm antibody recognized only a 43-kDa protein; however, neither protein was detected in adult rat liver nuclei. The appearance of the 41-kDa protein was associated with the presence of the highly active form of BCATm. These results suggest the existence of active and inactive forms of BCAT in rat liver.

Animals↗
PubMed2001

Chromohalobacter salexigens sp. nov., a moderately halophilic species that includes Halomonas elongata DSM 3043 and ATCC 33174.

Two strains that were originally isolated and characterized as members of the moderately halophilic species Halomonas elongata, strains DSM 3043 (= 1H11) and ATCC 33174 (= 1H15), were studied in detail. Their complete 16S rRNA sequences were determined and, when compared to sequences available from the databases, they showed a close phylogenetic relationship to Chromohalobacter marismortui. In addition, DNA-DNA hybridization experiments showed that both strains are members of the same species, but their DNA relatedness to the type strains of Halomonas elongata, ATCC 33173T, and Chromohalobacter marismortui, ATCC 17056T, is very low. Phenotypically, the two strains showed very similar features, related to those of Chromohalobacter, but clear differences were found between these two strains and Chromohalobacter marismortui. On the basis of these data, it is proposed that Halomonas elongata DSM 3043 and ATCC 33174 should be included in a new species of the genus Chromohalobacter, Chromohalobacter salexigens sp. nov. The type strain is DSM 3043T (= ATCC BAA-138T = CECT 5384T = CCM4921T = CIP106854T = NCIMB 13768T).

Base Composition↗
PubMed2000

Production and biochemical characterization of an alpha-amylase from the moderate halophile Halomonas meridiana.

Extracellular amylase production by the moderate halophile Halomonas meridiana was optimized and the enzyme was characterized biochemically. The highest amylase production was achieved by growing H. meridiana cultures in media with 5% salts and starch, in the absence of glucose until the end of the exponential phase. The amylase exhibited maximal activity at pH 7.0, being relatively stable in alkaline conditions. Optimal temperature and salinity for activity were 37 degrees C and 10% NaCl, respectively. Moreover, activity at salinity as high as 30% salts was detected. Maltose and maltotriose were the main end products of starch hydrolysis, indicating an alpha-amylase activity.

Culture Media↗
PubMed2000

Upregulation of BDNF mRNA and trkB mRNA in the nigrostriatal system and in the lesion site following unilateral transection of the medial forebrain bundle.

We have performed unilateral transection of the medial forebrain bundle (MFB) and studied BDNF mRNA and trkB mRNA levels at different postlesion times in the nigrostriatal system by means of in situ hybridization. BDNF mRNA levels were transiently induced in the substantia nigra pars compacta at 1 day postaxotomy. The disposition of BDNF mRNA expressing cells at this postlesion time in substantia nigra mimicked that of the dopaminergic neurons expressing the mRNA for the dopamine transporter. TrkB mRNA levels remained unaltered in the ventral mesencephalon at the different postlesion times examined-1 to 14 days. In contrast, trkB mRNA levels were significantly induced in the striatum at the longer postlesion time examined-14 days-when all neurodegenerative events are completed. It is becoming apparent that nigral BDNF mRNA levels are anterogradely transported to its target tissue in striatum. However, following axotomy, the lesion site represents a second potential target for BDNF action. Consequently, we also analyzed the pattern of mRNA expression for BDNF and trkB at the lesion site where dopaminergic axons are disconnected. There, we found notable inductions of both BDNF mRNA and trkB mRNA levels at 4 days postaxotomy. BDNF mRNA expressing cells were confined at the site of axotomy, which coincided precisely to that showing induction of trkB mRNA. Altogether, our results anticipate promising trophic roles of BNDF in the injured nigrostriatal system.

Animals↗