Structural and immunochemical studies of neutral exopolysaccharide produced by Lactobacillus johnsonii 142.

PubMed

Górska, Sabina; Jachymek, Wojciech; Rybka, Jacek; Strus, Magdalena; Heczko, Piotr B; Gamian, Andrzej

2010-01-11

This paper describes the structure of neutral exopolysaccharide (EPS) produced by Lactobacillus johnsonii 142, strain of the lactic acid bacteria isolated from the intestine of mice with experimentally induced inflammatory bowel disease (IBD). Sugar and methylation analyses along with (1)H and (13)C NMR spectroscopy, including two-dimensional (1)H,(1)H COSY, TOCSY, NOESY, and (1)H,(13)C HSQC experiments revealed that the repeating unit of the EPS is a pentasaccharide: -->3)-alpha-D-Galp-(1-->3)-beta-d-Glcp-(1-->5)-beta-D-Galf-(1-->3)-alpha-D-Galp-(1-->3)-alpha-D-Galp-(1--> The rabbit antiserum raised against whole cells of L. johnsonii 142 reacted with homologous EPS, and cross-reacted with exopolysaccharide from Lactobacillus animalis/murinus 148 isolated also from mice with IBD, but not reacted with EPS of L. johnsonii 151 from healthy mice. Copyright 2009 Elsevier Ltd. All rights reserved.

Lactobacillus johnsonii N6.2 Modulates the Host Immune Responses: A Double-Blind, Randomized Trial in Healthy Adults.

PubMed

Marcial, Guillermo E; Ford, Amanda L; Haller, Michael J; Gezan, Salvador A; Harrison, Natalie A; Cai, Dan; Meyer, Julie L; Perry, Daniel J; Atkinson, Mark A; Wasserfall, Clive H; Garrett, Timothy; Gonzalez, Claudio F; Brusko, Todd M; Dahl, Wendy J; Lorca, Graciela L

2017-01-01

Lactobacillus johnsonii N6.2 mitigates the onset of type 1 diabetes (T1D) in biobreeding diabetes-prone rats, in part, through changes in kynurenine:tryptophan (K:T) ratios. The goal of this pilot study was to determine the safety, tolerance, and general immunological response of L. johnsonii N6.2 in healthy subjects. A double-blind, randomized clinical trial in 42 healthy individuals with no known risk factors for T1D was undertaken to evaluate subject responses to the consumption of L. johnsonii N6.2. Participants received 1 capsule/day containing 10 8 colony-forming units of L. johnsonii N6.2 or placebo for 8 weeks. Comprehensive metabolic panel (CMP), leukocyte subpopulations by complete blood count (CBC) and flow cytometry, serum cytokines, and relevant metabolites in the indoleamine-2,3-dioxygenase pathway were assessed. L. johnsonii N6.2 survival and intestinal microbiota was analyzed. Daily and weekly questionnaires were assessed for potential effects of probiotic treatment on general wellness. The administration of L. johnsonii N6.2 did not modify the CMP or CBC of participants suggesting general safety. In fact, L. johnsonii N6.2 administration significantly decreased the occurrence of abdominal pain, indigestion, and cephalic syndromes. As predicted, increased serum tryptophan levels increased resulting in a decreased K:T ratio was observed in the L. johnsonii N6.2 group. Interestingly, immunophenotyping assays revealed that monocytes and natural killer cell numbers were increased significantly after washout (12 weeks). Moreover, an increase of circulating effector Th1 cells (CD45RO + CD183 + CD196 - ) and cytotoxic CD8 + T cells subset was observed in the L. johnsonii N6.2 group. Consumption of L. johnsonii N6.2 is well tolerated in adult control subjects, demonstrates systemic impacts on innate and adaptive immune populations, and results in a decreased K:T ratio. These data provide support for the safety and feasibility of using L. johnsonii N

Lactobacillus johnsonii N6.2 Modulates the Host Immune Responses: A Double-Blind, Randomized Trial in Healthy Adults

PubMed Central

Marcial, Guillermo E.; Ford, Amanda L.; Haller, Michael J.; Gezan, Salvador A.; Harrison, Natalie A.; Cai, Dan; Meyer, Julie L.; Perry, Daniel J.; Atkinson, Mark A.; Wasserfall, Clive H.; Garrett, Timothy; Gonzalez, Claudio F.; Brusko, Todd M.; Dahl, Wendy J.; Lorca, Graciela L.

2017-01-01

Lactobacillus johnsonii N6.2 mitigates the onset of type 1 diabetes (T1D) in biobreeding diabetes-prone rats, in part, through changes in kynurenine:tryptophan (K:T) ratios. The goal of this pilot study was to determine the safety, tolerance, and general immunological response of L. johnsonii N6.2 in healthy subjects. A double-blind, randomized clinical trial in 42 healthy individuals with no known risk factors for T1D was undertaken to evaluate subject responses to the consumption of L. johnsonii N6.2. Participants received 1 capsule/day containing 108 colony-forming units of L. johnsonii N6.2 or placebo for 8 weeks. Comprehensive metabolic panel (CMP), leukocyte subpopulations by complete blood count (CBC) and flow cytometry, serum cytokines, and relevant metabolites in the indoleamine-2,3-dioxygenase pathway were assessed. L. johnsonii N6.2 survival and intestinal microbiota was analyzed. Daily and weekly questionnaires were assessed for potential effects of probiotic treatment on general wellness. The administration of L. johnsonii N6.2 did not modify the CMP or CBC of participants suggesting general safety. In fact, L. johnsonii N6.2 administration significantly decreased the occurrence of abdominal pain, indigestion, and cephalic syndromes. As predicted, increased serum tryptophan levels increased resulting in a decreased K:T ratio was observed in the L. johnsonii N6.2 group. Interestingly, immunophenotyping assays revealed that monocytes and natural killer cell numbers were increased significantly after washout (12 weeks). Moreover, an increase of circulating effector Th1 cells (CD45RO+CD183+CD196−) and cytotoxic CD8+ T cells subset was observed in the L. johnsonii N6.2 group. Consumption of L. johnsonii N6.2 is well tolerated in adult control subjects, demonstrates systemic impacts on innate and adaptive immune populations, and results in a decreased K:T ratio. These data provide support for the safety and feasibility of using L. johnsonii N6.2 in

Use of Lactobacillus johnsonii in broilers challenged with Salmonella sofia.

PubMed

Olnood, Chen G; Beski, Sleman S M; Choct, Mingan; Iji, Paul A

2015-09-01

The effects of Lactobacillus johnsonii (L. johnsonii) on gut microflora, bird performance and intestinal development were assessed using 288 one-day-old Cobb broilers challenged with Salmonella sofia ( S . sofia ). The experiment was a 3 × 2 factorial design which consisted of three treatments, a negative control (NC) with no additives, a positive control (PC) containing antimicrobials (zinc-bacitracin, 50 mg/kg) and a probiotic group (Pro), and with the two factors being unchallenged or challenged with S . sofia . A probiotic preparation of L . johnsonii (10 9 cfu/chick) was administered to chicks individually by oral gavage on days 1, 3, 7 and 12. Chicks were individually challenged with S. sofia (10 7 cfu/chick) by oral gavage on d 2, 8 and 13. Results showed that the challenge itself markedly reduced ( P < 0.05) bird performance and feed intake. And, transient clinical symptoms of the infection with S . sofia were observed from the second time they were challenged with S . sofia in the negative challenge groups. The novel probiotic candidate L . johnsonii reduced the number of S . sofia and Clostridium perfringens in the gut environment, and improved the birds' colonization resistance to S . sofia .

Complete Genome Sequences of Lactobacillus johnsonii Strain N6.2 and Lactobacillus reuteri Strain TD1.

PubMed

Leonard, Michael T; Valladares, Ricardo B; Ardissone, Alexandria; Gonzalez, Claudio F; Lorca, Graciela L; Triplett, Eric W

2014-05-08

We report here the complete genome sequences of Lactobacillus johnsonii strain N6.2, a homofermentative lactic acid intestinal bacterium, and Lactobacillus reuteri strain TD1, a heterofermentative lactic acid intestinal bacterium, both isolated from a type 1 diabetes-resistant rat model.

Oxygen relieves the CO2 and acetate dependency of Lactobacillus johnsonii NCC 533.

PubMed

Hertzberger, Rosanne Y; Pridmore, R David; Gysler, Christof; Kleerebezem, Michiel; Teixeira de Mattos, M Joost

2013-01-01

Oxygen relieves the CO2 and acetate dependency of Lactobacillus johnsonii NCC 533. The probiotic Lactobacillus johnsonii NCC 533 is relatively sensitive to oxidative stress; the presence of oxygen causes a lower biomass yield due to early growth stagnation. We show however that oxygen can also be beneficial to this organism as it relieves the requirement for acetate and CO2 during growth. Both on agar- and liquid-media, anaerobic growth of L. johnsonii NCC 533 requires CO2 supplementation of the gas phase. Switching off the CO2 supply induces growth arrest and cell death. The presence of molecular oxygen overcomes the CO2 dependency. Analogously, L. johnsonii NCC 533 strictly requires media with acetate to sustain anaerobic growth, although supplementation at a level that is 100-fold lower (120 microM) than the concentration in regular growth medium for lactobacilli already suffices for normal growth. Analogous to the CO2 requirement, oxygen supply relieves this acetate-dependency for growth. The L. johnsonii NCC 533 genome indicates that this organism lacks genes coding for pyruvate formate lyase (PFL) and pyruvate dehydrogenase (PDH), both CO2 and acetyl-CoA producing systems. Therefore, C1- and C2- compound production is predicted to largely depend on pyruvate oxidase activity (POX). This proposed role of POX in C2/C1-generation is corroborated by the observation that in a POX deficient mutant of L. johnsonii NCC 533, oxygen is not able to overcome acetate dependency nor does it relieve the CO2 dependency.

Oxygen Relieves the CO2 and Acetate Dependency of Lactobacillus johnsonii NCC 533

PubMed Central

Hertzberger, Rosanne Y.; Pridmore, R. David; Gysler, Christof; Kleerebezem, Michiel; Teixeira de Mattos, M. Joost

2013-01-01

Oxygen relieves the CO2 and acetate dependency of Lactobacillus johnsonii NCC 533. The probiotic Lactobacillus johnsonii NCC 533 is relatively sensitive to oxidative stress; the presence of oxygen causes a lower biomass yield due to early growth stagnation. We show however that oxygen can also be beneficial to this organism as it relieves the requirement for acetate and CO2 during growth. Both on agar- and liquid-media, anaerobic growth of L. johnsonii NCC 533 requires CO2 supplementation of the gas phase. Switching off the CO2 supply induces growth arrest and cell death. The presence of molecular oxygen overcomes the CO2 dependency. Analogously, L. johnsonii NCC 533 strictly requires media with acetate to sustain anaerobic growth, although supplementation at a level that is 100-fold lower (120 microM) than the concentration in regular growth medium for lactobacilli already suffices for normal growth. Analogous to the CO2 requirement, oxygen supply relieves this acetate-dependency for growth. The L. johnsonii NCC 533 genome indicates that this organism lacks genes coding for pyruvate formate lyase (PFL) and pyruvate dehydrogenase (PDH), both CO2 and acetyl-CoA producing systems. Therefore, C1- and C2- compound production is predicted to largely depend on pyruvate oxidase activity (POX). This proposed role of POX in C2/C1-generation is corroborated by the observation that in a POX deficient mutant of L. johnsonii NCC 533, oxygen is not able to overcome acetate dependency nor does it relieve the CO2 dependency. PMID:23468944

Lactobacillus johnsonii inhibits indoleamine 2,3-dioxygenase and alters tryptophan metabolite levels in BioBreeding rats.

PubMed

Valladares, Ricardo; Bojilova, Lora; Potts, Anastasia H; Cameron, Evan; Gardner, Christopher; Lorca, Graciela; Gonzalez, Claudio F

2013-04-01

In our previous work, we found that feeding Lactobacillus johnsonii to BioBreeding diabetes-prone (BBDP) rats decreased the incidence of diabetes development. The aim of this study was to investigate host pathways affected by L. johnsonii, with specific focus on the rate-limiting enzyme of tryptophan catabolism, indoleamine 2,3-dioxygenase (IDO). Suspensions of L. johnsonii or an equal volume of vehicle were orally administered to BBDP rats. Tissue IDO was investigated using quantitative RT-PCR and Western blot, whereas tryptophan, kynurenine, and 5-hydroxytryptamine (5-HT) concentrations were quantified by HPLC and ELISA. IDO activity was also investigated using L. johnsonii culture cell-free supernatant (CFS) with affinity-purified IDO and HT-29 intestinal epithelial cells. L. johnsonii feeding resulted in a 17% reduction in serum kynurenine compared with that in vehicle-fed controls, correlating with a 1.4-fold elevation in 5-HT levels. H₂O₂ produced by L. johnsonii abolished IDO activity in vitro, and L. johnsonii feeding resulted in a 3.9-fold increase in ileum lumen H₂O₂. L. johnsonii CFS significantly reduced IDO activity in HT-29 intestinal epithelial cells (47% reduction) compared with that in vehicle-treated controls, an effect abolished by catalase treatment. These data support the role of H₂O₂ in commensal bacteria-host interactions and highlight the influence of commensal bacteria-derived H₂O₂ on host physiology.

The structure and immunoreactivity of exopolysaccharide isolated from Lactobacillus johnsonii strain 151.

PubMed

Górska-Frączek, Sabina; Sandström, Corine; Kenne, Lennart; Paściak, Mariola; Brzozowska, Ewa; Strus, Magdalena; Heczko, Piotr; Gamian, Andrzej

2013-08-30

The exopolysaccharide (EPS) structure from Lactobacillus johnsonii strain 151 isolated from the intestinal tract of mice was investigated. Sugar and methylation analyses together with (1)H and (13)C NMR spectroscopy, including two-dimensional (1)H,(1)H COSY, TOCSY, NOESY, and (1)H,(13)C HSQC, HMBC experiments, revealed that the repeating unit of the EPS is the linear pentasaccharide: →6)-α-d-Galp-(1→6)-α-d-Glcp-(1→3)-β-d-Galf-(1→3)-α-d-Glcp-(1→2)-β-d-Galf-(1→ The immunoreactivity of two structurally different exopolysaccharides isolated from L. johnsonii, 151 and 142 (Carbohydr. Res. 2010, 345, 108-114), was compared. Both EPSs differed in their reactivity with antisera. EPS from L. johnsonii 151 reacted with anti-Lactobacillus polyclonal sera against cells of five different strains, while EPS from L. johnsonii 142 was found to react only with its own antiserum. The broader specificity and higher reactivity of EPS from 151 strain than EPS from 142 strain were also observed with human sera. The physiological antibodies recognizing polysaccharide antigens were present in both adults and umbilical cord blood sera. A highly specific EPS 142 bearing strain was isolated from experimentally induced inflammatory bowel disease (IBD) mice, while a strain with EPS 151 isolated from the intestinal tract of healthy mice is characterized by a broad immune reactivity common structure. Copyright © 2013 Elsevier Ltd. All rights reserved.

Lactobacillus johnsonii Supplementation Attenuates Respiratory Viral Infection via Metabolic Reprogramming and Immune Cell Modulation

PubMed Central

Fonseca, Wendy; Lucey, Kaitlyn; Jang, Sihyug; Fujimura, Kei E.; Rasky, Andrew; Ting, Hung-An; Petersen, Julia; Johnson, Christine C.; Boushey, Homer A.; Zoratti, Edward; Ownby, Dennis R.; Levine, Albert M.; Bobbit, Kevin R.

2017-01-01

Summary Regulation of respiratory mucosal immunity by microbial-derived metabolites has been a proposed mechanism that may provide airway protection. Here we examine the effect of oral Lactobacillus johnsonii-supplementation on metabolic and immune response dynamics during respiratory syncytial virus (RSV) infection. L. johnsonii-supplementation reduced airway Th2 cytokines, dendritic cell function, increased T-regulatory cells, and was associated with a reprogrammed circulating metabolic environment, including docosahexanoic acid (DHA) enrichment. RSV-infected bone-marrow derived dendritic cells (BMDC) from L. johnsonii-supplemented mice had altered cytokine secretion, reduced expression of co-stimulatory molecules, and modified CD4+ T cell cytokines. This was replicated upon co-incubation of wild-type BMDCs with either plasma from L. johnsonii-supplemented mice, or DHA. Finally, airway transfer of BMDCs from L. johnsonii-supplemented mice, or with wild-type derived BMDCs pre-treated with plasma from L. johnsonii-supplemented mice, reduced airway pathologic responses to infection in recipient animals. Thus, L. johnsonii-supplementation mediates airway mucosal protection via immunomodulatory metabolites and altered immune function. PMID:28295020

Lactobacillus johnsonii supplementation attenuates respiratory viral infection via metabolic reprogramming and immune cell modulation.

PubMed

Fonseca, W; Lucey, K; Jang, S; Fujimura, K E; Rasky, A; Ting, H-A; Petersen, J; Johnson, C C; Boushey, H A; Zoratti, E; Ownby, D R; Levine, A M; Bobbit, K R; Lynch, S V; Lukacs, N W

2017-11-01

Regulation of respiratory mucosal immunity by microbial-derived metabolites has been a proposed mechanism that may provide airway protection. Here we examine the effect of oral Lactobacillus johnsonii supplementation on metabolic and immune response dynamics during respiratory syncytial virus (RSV) infection. L. johnsonii supplementation reduced airway T helper type 2 cytokines and dendritic cell (DC) function, increased regulatory T cells, and was associated with a reprogrammed circulating metabolic environment, including docosahexanoic acid (DHA) enrichment. RSV-infected bone marrow-derived DCs (BMDCs) from L. johnsonii-supplemented mice had altered cytokine secretion, reduced expression of co-stimulatory molecules, and modified CD4+ T-cell cytokines. This was replicated upon co-incubation of wild-type BMDCs with either plasma from L. johnsonii-supplemented mice or DHA. Finally, airway transfer of BMDCs from L. johnsonii-supplemented mice or with wild-type derived BMDCs pretreated with plasma from L. johnsonii-supplemented mice reduced airway pathological responses to infection in recipient animals. Thus L. johnsonii supplementation mediates airway mucosal protection via immunomodulatory metabolites and altered immune function.

Host Specific Diversity in Lactobacillus johnsonii as Evidenced by a Major Chromosomal Inversion and Phage Resistance Mechanisms

PubMed Central

Guinane, Caitriona M.; Kent, Robert M.; Norberg, Sarah; Hill, Colin; Fitzgerald, Gerald F.; Stanton, Catherine; Ross, R. Paul

2011-01-01

Genetic diversity and genomic rearrangements are a driving force in bacterial evolution and niche adaptation. We sequenced and annotated the genome of Lactobacillus johnsonii DPC6026, a strain isolated from the porcine intestinal tract. Although the genome of DPC6026 is similar in size (1.97mbp) and GC content (34.8%) to the sequenced human isolate L. johnsonii NCC 533, a large symmetrical inversion of approximately 750 kb differentiated the two strains. Comparative analysis among 12 other strains of L. johnsonii including 8 porcine, 3 human and 1 poultry isolate indicated that the genome architecture found in DPC6026 is more common within the species than that of NCC 533. Furthermore a number of unique features were annotated in DPC6026, some of which are likely to have been acquired by horizontal gene transfer (HGT) and contribute to protection against phage infection. A putative type III restriction-modification system was identified, as were novel Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) elements. Interestingly, these particular elements are not widely distributed among L. johnsonii strains. Taken together these data suggest intra-species genomic rearrangements and significant genetic diversity within the L. johnsonii species and indicate towards a host-specific divergence of L. johnsonii strains with respect to genome inversion and phage exposure. PMID:21533100

Host specific diversity in Lactobacillus johnsonii as evidenced by a major chromosomal inversion and phage resistance mechanisms.

PubMed

Guinane, Caitriona M; Kent, Robert M; Norberg, Sarah; Hill, Colin; Fitzgerald, Gerald F; Stanton, Catherine; Ross, R Paul

2011-04-20

Genetic diversity and genomic rearrangements are a driving force in bacterial evolution and niche adaptation. We sequenced and annotated the genome of Lactobacillus johnsonii DPC6026, a strain isolated from the porcine intestinal tract. Although the genome of DPC6026 is similar in size (1.97 mbp) and GC content (34.8%) to the sequenced human isolate L. johnsonii NCC 533, a large symmetrical inversion of approximately 750 kb differentiated the two strains. Comparative analysis among 12 other strains of L. johnsonii including 8 porcine, 3 human and 1 poultry isolate indicated that the genome architecture found in DPC6026 is more common within the species than that of NCC 533. Furthermore a number of unique features were annotated in DPC6026, some of which are likely to have been acquired by horizontal gene transfer (HGT) and contribute to protection against phage infection. A putative type III restriction-modification system was identified, as were novel Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) elements. Interestingly, these particular elements are not widely distributed among L. johnsonii strains. Taken together these data suggest intra-species genomic rearrangements and significant genetic diversity within the L. johnsonii species and indicate towards a host-specific divergence of L. johnsonii strains with respect to genome inversion and phage exposure.

Application of Lactobacillus johnsonii expressing phage endolysin for control of Clostridium perfringens.

PubMed

Gervasi, T; Lo Curto, R; Minniti, E; Narbad, A; Mayer, M J

2014-10-01

Clostridium perfringens is frequently found in food and the environment and produces potent toxins that have a negative impact on both human and animal health and particularly on the poultry industry. Lactobacillus johnsonii FI9785, isolated from the chicken gastrointestinal tract, has been demonstrated to exclude Cl. perfringens in poultry. We have investigated the interaction of wild-type Lact. johnsonii FI9785 or an engineered strain expressing a cell wall-hydrolysing endolysin with Cl. perfringens in vitro, using a batch culture designed to simulate human gastrointestinal tract conditions. Co-culture experiments indicated that acid production by Lact. johnsonii is important in pathogen control. The co-culture of the endolysin-secreting Lact. johnsonii with Cl. perfringens showed that the engineered strain had the potential to control the pathogen, but the ability to reduce Cl. perfringens numbers was not consistent. Results obtained indicate that survival of high numbers of Lact. johnsonii will be essential for effective pathogen control. Significance and impact of the study: The bacterium Lactobacillus johnsonii FI9785 reduces numbers of the pathogen Clostridium perfringens in vitro. Biocontrol was improved by engineering the strain to produce and export a cell wall-hydrolysing endolysin, but good survival of the producer strain is essential. The production of bacteriophage endolysins by commensal bacteria has the potential to improve competitive exclusion of pathogens in the gastrointestinal tract. © 2014 The Society for Applied Microbiology.

Structure and biosynthesis of two exopolysaccharides produced by Lactobacillus johnsonii FI9785.

PubMed

Dertli, Enes; Colquhoun, Ian J; Gunning, A Patrick; Bongaerts, Roy J; Le Gall, Gwénaëlle; Bonev, Boyan B; Mayer, Melinda J; Narbad, Arjan

2013-11-01

Exopolysaccharides were isolated and purified from Lactobacillus johnsonii FI9785, which has previously been shown to act as a competitive exclusion agent to control Clostridium perfringens in poultry. Structural analysis by NMR spectroscopy revealed that L. johnsonii FI9785 can produce two types of exopolysaccharide: EPS-1 is a branched dextran with the unusual feature that every backbone residue is substituted with a 2-linked glucose unit, and EPS-2 was shown to have a repeating unit with the following structure: -6)-α-Glcp-(1-3)-β-Glcp-(1-5)-β-Galf-(1-6)-α-Glcp-(1-4)-β-Galp-(1-4)-β-Glcp-(1-. Sites on both polysaccharides were partially occupied by substituent groups: 1-phosphoglycerol and O-acetyl groups in EPS-1 and a single O-acetyl group in EPS-2. Analysis of a deletion mutant (ΔepsE) lacking the putative priming glycosyltransferase gene located within a predicted eps gene cluster revealed that the mutant could produce EPS-1 but not EPS-2, indicating that epsE is essential for the biosynthesis of EPS-2. Atomic force microscopy confirmed the localization of galactose residues on the exterior of wild type cells and their absence in the ΔepsE mutant. EPS2 was found to adopt a random coil structural conformation. Deletion of the entire 14-kb eps cluster resulted in an acapsular mutant phenotype that was not able to produce either EPS-2 or EPS-1. Alterations in the cell surface properties of the EPS-specific mutants were demonstrated by differences in binding of an anti-wild type L. johnsonii antibody. These findings provide insights into the biosynthesis and structures of novel exopolysaccharides produced by L. johnsonii FI9785, which are likely to play an important role in biofilm formation, protection against harsh environment of the gut, and colonization of the host.

Lactobacillus johnsonii ameliorates intestinal, extra-intestinal and systemic pro-inflammatory immune responses following murine Campylobacter jejuni infection.

PubMed

Bereswill, Stefan; Ekmekciu, Ira; Escher, Ulrike; Fiebiger, Ulrike; Stingl, Kerstin; Heimesaat, Markus M

2017-05-18

Campylobacter jejuni infections are progressively increasing worldwide. Probiotic treatment might open novel therapeutic or even prophylactic approaches to combat campylobacteriosis. In the present study secondary abiotic mice were generated by broad-spectrum antibiotic treatment and perorally reassociated with a commensal murine Lactobacillus johnsonii strain either 14 days before (i.e. prophylactic regimen) or 7 days after (i.e. therapeutic regimen) peroral C. jejuni strain 81-176 infection. Following peroral reassociation both C. jejuni and L. johnsonii were able to stably colonize the murine intestinal tract. Neither therapeutic nor prophylactic L. johnsonii application, however, could decrease intestinal C. jejuni burdens. Notably, C. jejuni induced colonic apoptosis could be ameliorated by prophylactic L. johnsonii treatment, whereas co-administration of L. johnsonii impacted adaptive (i.e. T and B lymphocytes, regulatory T cells), but not innate (i.e. macrophages and monocytes) immune cell responses in the intestinal tract. Strikingly, C. jejuni induced intestinal, extra-intestinal and systemic secretion of pro-inflammatory mediators (such as IL-6, MCP-1, TNF and nitric oxide) could be alleviated by peroral L. johnsonii challenge. In conclusion, immunomodulatory probiotic species might offer valuable strategies for prophylaxis and/or treatment of C. jejuni induced intestinal, extra-intestinal as well as systemic pro-inflammatory immune responses in vivo.

Draft Genome Sequence of Lactobacillus johnsonii Strain 16, Isolated from Mice.

PubMed

Buhnik-Rosenblau, Keren; Danin-Poleg, Yael; Elgavish, Sharona; Kashi, Yechezkel

2015-10-08

Here, we report the genome sequence of Lactobacillus johnsonii, a member of the gut lactobacilli. This draft genome of L. johnsonii strain 16 isolated from C57BL/6J mice enables the identification of bacterial genes responsible for host-specific gut persistence. Copyright © 2015 Buhnik-Rosenblau et al.

Urinary D-lactate excretion in infants receiving Lactobacillus johnsonii with formula.

PubMed

Haschke-Becher, Elisabeth; Brunser, Oscar; Cruchet, Sylvia; Gotteland, Martin; Haschke, Ferdinand; Bachmann, Claude

2008-01-01

Supplementation with certain probiotics can improve gut microbial flora and immune function but should not have adverse effects. This study aimed to assess the risk of D-lactate accumulation and subsequent metabolic acidosis in infants fed on formula containing Lactobacillus johnsonii (La1). In the framework of a double-blind, randomized controlled trial enrolling 71 infants aged 4-5 months, morning urine samples were collected before and 4 weeks after being fed formulas with or without La1 (1 x 10(8)/g powder) or being breastfed. Urinary D- and L-lactate concentrations were assayed by enzymatic, fluorimetric methods and excretion was normalized per mol creatinine. At baseline, no significant differences in urinary D-/L-lactate excretion among the formula-fed and breastfed groups were found. After 4 weeks, D-lactate excretion did not differ between the two formula groups, but was higher in both formula groups than in breastfed infants. In all infants receiving La1, urinary D-lactate concentrations remained within the concentration ranges of age-matched healthy infants which had been determined in an earlier study using the same analytical method. Urinary L-lactate also did not vary over time or among groups. Supplementation of La1 to formula did not affect urinary lactate excretion and there is no evidence of an increased risk of lactic acidosis. Copyright 2008 S. Karger AG, Basel.

The Genetic Analysis of an Acinetobacter johnsonii Clinical Strain Evidenced the Presence of Horizontal Genetic Transfer.

PubMed

Montaña, Sabrina; Schramm, Sareda T J; Traglia, German Matías; Chiem, Kevin; Parmeciano Di Noto, Gisela; Almuzara, Marisa; Barberis, Claudia; Vay, Carlos; Quiroga, Cecilia; Tolmasky, Marcelo E; Iriarte, Andrés; Ramírez, María Soledad

2016-01-01

Acinetobacter johnsonii rarely causes human infections. While most A. johnsonii isolates are susceptible to virtually all antibiotics, strains harboring a variety of β-lactamases have recently been described. An A. johnsonii Aj2199 clinical strain recovered from a hospital in Buenos Aires produces PER-2 and OXA-58. We decided to delve into its genome by obtaining the whole genome sequence of the Aj2199 strain. Genome comparison studies on Aj2199 revealed 240 unique genes and a close relation to strain WJ10621, isolated from the urine of a patient in China. Genomic analysis showed evidence of horizontal genetic transfer (HGT) events. Forty-five insertion sequences and two intact prophages were found in addition to several resistance determinants such as blaPER-2, blaOXA-58, blaTEM-1, strA, strB, ereA, sul1, aacC2 and a new variant of blaOXA-211, called blaOXA-498. In particular, blaPER-2 and blaTEM-1 are present within the typical contexts previously described in the Enterobacteriaceae family. These results suggest that A. johnsonii actively acquires exogenous DNA from other bacterial species and concomitantly becomes a reservoir of resistance genes.

Structure and Biosynthesis of Two Exopolysaccharides Produced by Lactobacillus johnsonii FI9785*

PubMed Central

Dertli, Enes; Colquhoun, Ian J.; Gunning, A. Patrick; Bongaerts, Roy J.; Le Gall, Gwénaëlle; Bonev, Boyan B.; Mayer, Melinda J.; Narbad, Arjan

2013-01-01

Exopolysaccharides were isolated and purified from Lactobacillus johnsonii FI9785, which has previously been shown to act as a competitive exclusion agent to control Clostridium perfringens in poultry. Structural analysis by NMR spectroscopy revealed that L. johnsonii FI9785 can produce two types of exopolysaccharide: EPS-1 is a branched dextran with the unusual feature that every backbone residue is substituted with a 2-linked glucose unit, and EPS-2 was shown to have a repeating unit with the following structure: -6)-α-Glcp-(1–3)-β-Glcp-(1–5)-β-Galf-(1–6)-α-Glcp-(1–4)-β-Galp-(1–4)-β-Glcp-(1-. Sites on both polysaccharides were partially occupied by substituent groups: 1-phosphoglycerol and O-acetyl groups in EPS-1 and a single O-acetyl group in EPS-2. Analysis of a deletion mutant (ΔepsE) lacking the putative priming glycosyltransferase gene located within a predicted eps gene cluster revealed that the mutant could produce EPS-1 but not EPS-2, indicating that epsE is essential for the biosynthesis of EPS-2. Atomic force microscopy confirmed the localization of galactose residues on the exterior of wild type cells and their absence in the ΔepsE mutant. EPS2 was found to adopt a random coil structural conformation. Deletion of the entire 14-kb eps cluster resulted in an acapsular mutant phenotype that was not able to produce either EPS-2 or EPS-1. Alterations in the cell surface properties of the EPS-specific mutants were demonstrated by differences in binding of an anti-wild type L. johnsonii antibody. These findings provide insights into the biosynthesis and structures of novel exopolysaccharides produced by L. johnsonii FI9785, which are likely to play an important role in biofilm formation, protection against harsh environment of the gut, and colonization of the host. PMID:24019531

Genome sequence of Lactobacillus johnsonii PF01, isolated from piglet feces.

PubMed

Lee, Je Hee; Chae, Jong Pyo; Lee, Ji Yoon; Lim, Jong-Sung; Kim, Geun-Bae; Ham, Jun-Sang; Chun, Jongsik; Kang, Dae-Kyung

2011-09-01

Lactobacillus johnsonii PF01, an autochthonous bacterium of the gastrointestinal tract, was isolated from a fecal sample from a piglet. The strain adhered specifically to the duodenal and jejunal epithelial cells of the piglet and had high bile resistance activity. Here we report the genomic sequence of L. johnsonii PF01. Copyright © 2011, American Society for Microbiology. All Rights Reserved.

In vivo characterization of Lactobacillus johnsonii FI9785 for use as a defined competitive exclusion agent against bacterial pathogens in poultry.

PubMed

La Ragione, R M; Narbad, A; Gasson, M J; Woodward, M J

2004-01-01

To test the efficacy of Lactobacillus johnsonii FI9785 in reducing the colonization and shedding of Salmonella enterica serotype Enteritidis, Escherichia coli O78:K80 and Clostridium perfringens in poultry. Specific pathogen-free chicks (1 day old) were dosed with a single oral inoculum of 1x10(9) CFU. Lactobacillus johnsonii FI9785 and 24 h later were challenged in separate experiments with S. Enteritidis (S1400, nalr) and E. coli O78:K80 (EC34195, nalr). There were no significant effects against S. Enteritidis whereas colonization of the small intestine by E. coli O78:K80 was reduced significantly. Both S. Enteritidis and E. coli colonized the caeca and colon to levels equivalent to control birds and there was no reduction in shedding as assessed by a semi-quantitative cloacal swabbing technique. Specific pathogen-free chicks (20 day old) were dosed with a single oral inoculum of 1x10(9) CFU L. johnsonii FI9785 and 24 h later were challenged with C. perfringens. A single oral dose of L. johnsonii FI9785 was sufficient to suppress all aspects of colonization and persistence of C. perfringens. Lactobacillus johnsonii FI9785 may be given to poultry for use as a competitive exclusion agent to control C. perfringens. Lactobacillus johnsonii FI9785 may be a valuable tool to control the endemic disease of necrotic enteritis, thereby reducing economic losses associated with reduced use of antimicrobials in the poultry industry.

Molecular analysis of a chromosome-carried erm(B) gene and its flanking insertion points in Lactobacillus johnsonii G41.

PubMed

Flórez, Ana Belén; Ammor, Mohammed Salim; Delgado, Susana; Mayo, Baltasar

2006-12-01

An erm(B) gene carried on the Lactobacillus johnsonii G41 chromosome and the upstream and downstream regions were fully sequenced. Apparently, a 1,495-bp segment of pRE25 from Enterococcus faecalis carrying the erm(B) gene became inserted, by an unknown mechanism, into the L. johnsonii chromosome.

Predominant effect of host genetics on levels of Lactobacillus johnsonii bacteria in the mouse gut.

PubMed

Buhnik-Rosenblau, Keren; Danin-Poleg, Yael; Kashi, Yechezkel

2011-09-01

The gut microbiota is strongly associated with the well-being of the host. Its composition is affected by environmental factors, such as food and maternal inoculation, while the relative impact of the host's genetics have been recently uncovered. Here, we studied the effect of the host genetic background on the composition of intestinal bacteria in a murine model, focusing on lactic acid bacteria (LAB) as an important group that includes many probiotic strains. Based on 16S rRNA gene genotyping, variation was observed in fecal LAB populations of BALB/c and C57BL/6J mouse lines. Lactobacillus johnsonii, a potentially probiotic bacterium, appeared at significantly higher levels in C57BL/6J versus BALB/c mouse feces. In the BALB/c gut, the L. johnsonii level decreased rapidly after oral administration, suggesting that some selective force does not allow its persistence at higher levels. The genetic inheritance of L. johnsonii levels was further tested in reciprocal crosses between the two mouse lines. The resultant F1 offspring presented similar L. johnsonii levels, confirming that mouse genetics plays a major role in determining these levels compared to the smaller maternal effect. Our findings suggest that mouse genetics has a major effect on the composition of the LAB population in general and on the persistence of L. johnsonii in the gut in particular. Concentrating on a narrow spectrum of culturable LAB enables the isolation and characterization of such potentially probiotic bacterial strains, which might be specifically oriented to the genetic background of the host as part of a personalized-medicine approach.

The complete genomes of Lactobacillus plantarum and Lactobacillus johnsonii reveal extensive differences in chromosome organization and gene content.

PubMed

Boekhorst, Jos; Siezen, Roland J; Zwahlen, Marie-Camille; Vilanova, David; Pridmore, Raymond D; Mercenier, Annick; Kleerebezem, Michiel; de Vos, Willem M; Brüssow, Harald; Desiere, Frank

2004-11-01

The first comprehensive comparative analysis of lactobacilli was done by comparing the genomes of Lactobacillus plantarum (3.3 Mb) and Lactobacillus johnsonii (2.0 Mb). L. johnsonii is predominantly found in the gastrointestinal tract, while L. plantarum is also found on plants and plant-derived material, and is used in a variety of industrial fermentations. The L. plantarum and L. johnsonii chromosomes have only 28 regions with conservation of gene order, totalling about 0.75 Mb; these regions are not co-linear, indicating major chromosomal rearrangements. Metabolic reconstruction indicates many differences between L. johnsonii and L. plantarum: numerous enzymes involved in sugar metabolism and in biosynthesis of amino acids, nucleotides, fatty acids and cofactors are lacking in L. johnsonii. Major differences were seen in the number and types of putative extracellular proteins, which are of interest because of their possible role in host-microbe interactions. The differences between L. plantarum and L. johnsonii, both in genome organization and gene content, are exceptionally large for two bacteria of the same genus, emphasizing the difficulty in taxonomic classification of lactobacilli.

Isolation and characterization of a virulent bacteriophage infecting Acinetobacter johnsonii from activated sludge.

PubMed

Fan, Niansi; Qi, Rong; Yang, Min

2017-06-01

A double-stranded DNA phage named AJO1, infecting Acinetobacter johnsonii, which plays an important role in wastewater treatment, was isolated from activated sludge in a full-scale municipal wastewater treatment plant. Based on morphological taxonomy, AJO1, with an icosahedral head 55 ± 2 nm in diameter and a non-contractile tail 8 ± 2 nm in length, was classified as a member of the Podoviridae family. Bacterial infection characteristics were as follows: no polyvalent infectivity, optimal multiplicity of infection of 10 -2 ; eclipse and burst size of 30 min and 51.2 PFU-infected cells -1 , respectively. It showed considerable infectivity under a neutral pH condition (pH 6.0-9.0) and relatively high temperature (55 °C). Whole-genome sequencing of AJO1 revealed a linearly permuted DNA (41 437 bp) carrying 54 putative open reading frames and 4 repeats. This is the first report of isolation of an A. johnsonii phage, whose bacteriophage distribution and population dynamics are not well known. The results of this study could contribute to subsequent research on the interaction between bacteriophages and their hosts during wastewater treatment. In addition, AJO1 may become a candidate for potential therapy against A. johnsonii infection in clinical applications, since this species is an opportunistic pathogen. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Predominant Effect of Host Genetics on Levels of Lactobacillus johnsonii Bacteria in the Mouse Gut▿†

PubMed Central

Buhnik-Rosenblau, Keren; Danin-Poleg, Yael; Kashi, Yechezkel

2011-01-01

The gut microbiota is strongly associated with the well-being of the host. Its composition is affected by environmental factors, such as food and maternal inoculation, while the relative impact of the host's genetics have been recently uncovered. Here, we studied the effect of the host genetic background on the composition of intestinal bacteria in a murine model, focusing on lactic acid bacteria (LAB) as an important group that includes many probiotic strains. Based on 16S rRNA gene genotyping, variation was observed in fecal LAB populations of BALB/c and C57BL/6J mouse lines. Lactobacillus johnsonii, a potentially probiotic bacterium, appeared at significantly higher levels in C57BL/6J versus BALB/c mouse feces. In the BALB/c gut, the L. johnsonii level decreased rapidly after oral administration, suggesting that some selective force does not allow its persistence at higher levels. The genetic inheritance of L. johnsonii levels was further tested in reciprocal crosses between the two mouse lines. The resultant F1 offspring presented similar L. johnsonii levels, confirming that mouse genetics plays a major role in determining these levels compared to the smaller maternal effect. Our findings suggest that mouse genetics has a major effect on the composition of the LAB population in general and on the persistence of L. johnsonii in the gut in particular. Concentrating on a narrow spectrum of culturable LAB enables the isolation and characterization of such potentially probiotic bacterial strains, which might be specifically oriented to the genetic background of the host as part of a personalized-medicine approach. PMID:21803912

A highly acid-resistant novel strain of Lactobacillus johnsonii No. 1088 has antibacterial activity, including that against Helicobacter pylori, and inhibits gastrin-mediated acid production in mice

PubMed Central

Aiba, Yuji; Nakano, Yasuhiro; Koga, Yasuhiro; Takahashi, Kenji; Komatsu, Yasuhiko

2015-01-01

A novel strain of Lactobacillus johnsonii No. 1088 was isolated from the gastric juice of a healthy Japanese male volunteer, and characterized for its effectiveness in the stomach environment. Lactobacillus johnsonii No. 1088 was found to have the strongest acid resistance among several lactobacilli examined (>10% of cells survived at pH 1.0 after 2 h), and such a high acid resistance property was a specific characteristic of this strain of L. johnsonii. When cultured with various virulent bacteria, L. johnsonii No. 1088 inhibited the growth of Helicobacter pylori,Escherichia coli O-157, Salmonella Typhimurium, and Clostridium difficile, in which case its effectiveness was more potent than that of a type strain of L. johnsonii,JCM2012. In addition to its effect in vitro, L. johnsonii No. 1088 inhibited the growth of H. pylori in human intestinal microbiota-associated mice in both its live and lyophilized forms. Moreover, L. johnsonii No. 1088 suppressed gastric acid secretion in mice via decreasing the number of gastrin-positive cells in the stomach. These results taken together suggest that L. johnsonii No. 1088 is a unique lactobacillus having properties beneficial for supporting H. pylori eradication by triple therapy including the use of a proton pump inhibitor (PPI) and also for prophylaxis of gastroesophageal reflux disease possibly caused after H. pylori eradication as a side effect of PPI. PMID:25771812

Hydrolysis of chicoric and caftaric acids with esterases and Lactobacillus johnsonii in Vitro and in a gastrointestinal model.

PubMed

Bel-Rhlid, Rachid; Pagé-Zoerkler, Nicole; Fumeaux, René; Ho-Dac, Thang; Chuat, Jean-Yves; Sauvageat, Jean Luc; Raab, Thomas

2012-09-12

Chicoric acid (ChA) and caftaric acid (CafA) were identified as bioactive components of chicory and have been ascribed a number of health benefits. This study investigated the hydrolysis of ChA and CafA with enzymes and a probiotic bacterium Lactobacillus johnsonii (La1). Esterase from Aspergillus japonicus (24 U/mg) hydrolyzed 100% of ChA (5 mM) and CafA (5 mM) after 3 h, at pH 7.0 and 37 °C. Under the same reaction conditions, 100% hydrolysis of ChA and CafA was achieved with a spray-dried preparation of La1. The addition of La1 (100 mg/mL, 3.3 E9 cfu/g) to CafA solution in a gastrointestinal model (GI model) resulted in 65% hydrolysis of CafA. This model simulates the physicochemical conditions of the human gastrointestinal tract. No hydrolysis of CafA was observed after passage through the GI model in the absence of La1. The results of this study support the hypothesis that ChA and CafA are degraded by gut microflora before absorption and metabolization.

Characterization of a novel Lactobacillus species closely related to Lactobacillus johnsonii using a combination of molecular and comparative genomics methods

PubMed Central

2010-01-01

Background Comparative genomic hybridization (CGH) constitutes a powerful tool for identification and characterization of bacterial strains. In this study we have applied this technique for the characterization of a number of Lactobacillus strains isolated from the intestinal content of rats fed with a diet supplemented with sorbitol. Results Phylogenetic analysis based on 16S rRNA gene, recA, pheS, pyrG and tuf sequences identified five bacterial strains isolated from the intestinal content of rats as belonging to the recently described Lactobacillus taiwanensis species. DNA-DNA hybridization experiments confirmed that these five strains are distinct but closely related to Lactobacillus johnsonii and Lactobacillus gasseri. A whole genome DNA microarray designed for the probiotic L. johnsonii strain NCC533 was used for CGH analysis of L. johnsonii ATCC 33200T, L. johnsonii BL261, L. gasseri ATCC 33323T and L. taiwanensis BL263. In these experiments, the fluorescence ratio distributions obtained with L. taiwanensis and L. gasseri showed characteristic inter-species profiles. The percentage of conserved L. johnsonii NCC533 genes was about 83% in the L. johnsonii strains comparisons and decreased to 51% and 47% for L. taiwanensis and L. gasseri, respectively. These results confirmed the separate status of L. taiwanensis from L. johnsonii at the level of species, and also that L. taiwanensis is closer to L. johnsonii than L. gasseri is to L. johnsonii. Conclusion Conventional taxonomic analyses and microarray-based CGH analysis have been used for the identification and characterization of the newly species L. taiwanensis. The microarray-based CGH technology has been shown as a remarkable tool for the identification and fine discrimination between phylogenetically close species, and additionally provided insight into the adaptation of the strain L. taiwanensis BL263 to its ecological niche. PMID:20849602

Characterization of a novel Lactobacillus species closely related to Lactobacillus johnsonii using a combination of molecular and comparative genomics methods.

PubMed

Sarmiento-Rubiano, Luz-Adriana; Berger, Bernard; Moine, Déborah; Zúñiga, Manuel; Pérez-Martínez, Gaspar; Yebra, María J

2010-09-17

Comparative genomic hybridization (CGH) constitutes a powerful tool for identification and characterization of bacterial strains. In this study we have applied this technique for the characterization of a number of Lactobacillus strains isolated from the intestinal content of rats fed with a diet supplemented with sorbitol. Phylogenetic analysis based on 16S rRNA gene, recA, pheS, pyrG and tuf sequences identified five bacterial strains isolated from the intestinal content of rats as belonging to the recently described Lactobacillus taiwanensis species. DNA-DNA hybridization experiments confirmed that these five strains are distinct but closely related to Lactobacillus johnsonii and Lactobacillus gasseri. A whole genome DNA microarray designed for the probiotic L. johnsonii strain NCC533 was used for CGH analysis of L. johnsonii ATCC 33200T, L. johnsonii BL261, L. gasseri ATCC 33323T and L. taiwanensis BL263. In these experiments, the fluorescence ratio distributions obtained with L. taiwanensis and L. gasseri showed characteristic inter-species profiles. The percentage of conserved L. johnsonii NCC533 genes was about 83% in the L. johnsonii strains comparisons and decreased to 51% and 47% for L. taiwanensis and L. gasseri, respectively. These results confirmed the separate status of L. taiwanensis from L. johnsonii at the level of species, and also that L. taiwanensis is closer to L. johnsonii than L. gasseri is to L. johnsonii. Conventional taxonomic analyses and microarray-based CGH analysis have been used for the identification and characterization of the newly species L. taiwanensis. The microarray-based CGH technology has been shown as a remarkable tool for the identification and fine discrimination between phylogenetically close species, and additionally provided insight into the adaptation of the strain L. taiwanensis BL263 to its ecological niche.

A highly acid-resistant novel strain of Lactobacillus johnsonii No. 1088 has antibacterial activity, including that against Helicobacter pylori, and inhibits gastrin-mediated acid production in mice.

PubMed

Aiba, Yuji; Nakano, Yasuhiro; Koga, Yasuhiro; Takahashi, Kenji; Komatsu, Yasuhiko

2015-06-01

A novel strain of Lactobacillus johnsonii No. 1088 was isolated from the gastric juice of a healthy Japanese male volunteer, and characterized for its effectiveness in the stomach environment. Lactobacillus johnsonii No. 1088 was found to have the strongest acid resistance among several lactobacilli examined (>10% of cells survived at pH 1.0 after 2 h), and such a high acid resistance property was a specific characteristic of this strain of L. johnsonii. When cultured with various virulent bacteria, L. johnsonii No. 1088 inhibited the growth of Helicobacter pylori, Escherichia coli O-157, Salmonella Typhimurium, and Clostridium difficile, in which case its effectiveness was more potent than that of a type strain of L. johnsonii, JCM2012. In addition to its effect in vitro, L. johnsonii No. 1088 inhibited the growth of H. pylori in human intestinal microbiota-associated mice in both its live and lyophilized forms. Moreover, L. johnsonii No. 1088 suppressed gastric acid secretion in mice via decreasing the number of gastrin-positive cells in the stomach. These results taken together suggest that L. johnsonii No. 1088 is a unique lactobacillus having properties beneficial for supporting H. pylori eradication by triple therapy including the use of a proton pump inhibitor (PPI) and also for prophylaxis of gastroesophageal reflux disease possibly caused after H. pylori eradication as a side effect of PPI. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

l-Alanine Auxotrophy of Lactobacillus johnsonii as Demonstrated by Physiological, Genomic, and Gene Complementation Approaches

PubMed Central

van der Kaaij, Hengameh; Desiere, Frank; Mollet, Beat; Germond, Jacques-Edouard

2004-01-01

Using a chemically defined medium without l-alanine, Lactobacillus johnsonii was demonstrated to be strictly auxotrophic for that amino acid. A comparative genetic analysis showed that all known genes involved in l-alanine biosynthesis are absent from the genome of L. johnsonii. This auxotrophy was complemented by heterologous expression of the Bacillus subtilis l-alanine dehydrogenase. PMID:15006820

Complete genome sequence of Lactobacillus johnsonii FI9785, a competitive exclusion agent against pathogens in poultry.

PubMed

Wegmann, Udo; Overweg, Karin; Horn, Nikki; Goesmann, Alexander; Narbad, Arjan; Gasson, Michael J; Shearman, Claire

2009-11-01

Lactobacillus johnsonii is a member of the acidophilus group of lactobacilli. Because of their probiotic properties, including attachment to epithelial cells, immunomodulation, and competitive exclusion of pathogens, representatives of this group are being intensively studied. Here we report the complete annotated genome sequence of Lactobacillus johnsonii FI9785, a strain which prevents the colonization of specific-pathogen-free chicks by Clostridium perfringens.

Biotransformation of caffeoyl quinic acids from green coffee extracts by Lactobacillus johnsonii NCC 533.

PubMed

Bel-Rhlid, Rachid; Thapa, Dinesh; Kraehenbuehl, Karin; Hansen, Carl Erik; Fischer, Lutz

2013-01-01

The potential of Lactobacillus johnsonii NCC 533 to metabolize chlorogenic acids from green coffee extract was investigated. Two enzymes, an esterase and a hydroxycinnamate decarboxylase (HCD), were involved in this biotransformation. The complete hydrolysis of 5-caffeoylquinic acid (5-CQA) into caffeic acid (CA) by L. johnsonii esterase occurred during the first 16 h of reaction time. No dihydrocaffeic acid was identified in the reaction mixture. The decarboxylation of CA into 4-vinylcatechol (4-VC) started only when the maximum concentration of CA was reached (10 μmol/ml). CA was completely transformed into 4-VC after 48 h of incubation. No 4-vinylphenol or other derivatives could be identified in the reaction media. In this study we demonstrate the capability of L. johnsonii to transform chlorogenic acids from green coffee extract into 4-VC in two steps one pot reaction. Thus, the enzymatic potential of certain lactobacilli might be explored to generate flavor compounds from plant polyphenols.

The metabolic fate of doubly stable isotope labelled heat-killed Lactobacillus johnsonii in humans.

PubMed

Wutzke, K D; Berg, D; Haffner, D

2008-02-01

In this study, heat-killed Lactobacillus johnsonii (La1), doubly labelled with (13)C and (15)N (hk-dlLa1), was used to follow the metabolic fate after oral administration in humans. Experimental study. University of Rostock, Children's Hospital, Research Laboratory. Ten healthy adults aged 23-26 years. The subjects received 74.6 mg/kg body weight hk-dlLa1 and 10 g alpha-D-raffinose together with breakfast. A sample of venous blood was taken after 2 h. Expired air samples were taken over 14 h, whereas urine and faeces were collected over a period of 48 h. (13)C- and (15)N-enrichments were measured by isotope ratio mass spectrometry. Hydrogen concentrations were measured by electrochemical detection. The orocaecal transit time (OCTT) was reached after 3.4 h. After 2 h, (13)C- and (15)N-enrichment of fibrinogen amounted to 2 and 25 p.p.m. excess, respectively. The (13)CO(2)-exhalation amounted to 9.2% of the ingested dose. The urinary excretion of (13)C and (15)N was 2.1 and 10.4% of the ingested dose, respectively, whereas the faecal excretion was 47.9 and 43.7% of the ingested dose, respectively. In comparison to OCTT of 3.4 h, both stable isotopes appear after 30 min in breath and urine, indicating that hk-dlLa1 is rapidly digested in the small bowel before reaching the caecum. This is confirmed by (13)C-and (15)N-enrichments of blood plasma fractions. The ingestion of hk-dlLa1 led to a (13)C- and (15)N-excretion of 59.2 and 54.1% of the ingested dose, respectively, of both stable isotopes.

Improved bioavailability of dietary phenolic acids in whole grain barley and oat groat following fermentation with probiotic Lactobacillus acidophilus , Lactobacillus johnsonii , and Lactobacillus reuteri.

PubMed

Hole, Anastasia S; Rud, Ida; Grimmer, Stine; Sigl, Stefanie; Narvhus, Judith; Sahlstrøm, Stefan

2012-06-27

The aim of this study was to improve the bioavailability of the dietary phenolic acids in flours from whole grain barley and oat groat following fermentation with lactic acid bacteria (LAB) exhibiting high feruloyl esterase activity (FAE). The highest increase of free phenolic acids was observed after fermentation with three probiotic strains, Lactobacillus johnsonii LA1, Lactobacillus reuteri SD2112, and Lactobacillus acidophilus LA-5, with maximum increases from 2.55 to 69.91 μg g(-1) DM and from 4.13 to 109.42 μg g(-1) DM in whole grain barley and oat groat, respectively. Interestingly, higher amounts of bound phenolic acids were detected after both water treatment and LAB fermentation in whole grain barley, indicating higher bioaccessibility, whereas some decrease was detected in oat groat. To conclude, cereal fermentation with specific probiotic strains can lead to significant increase of free phenolic acids, thereby improving their bioavailability.

Administration of Lactobacillus johnsonii FI9785 to chickens affects colonisation by Campylobacter jejuni and the intestinal microbiota.

PubMed

Mañes-Lázaro, R; Van Diemen, P M; Pin, C; Mayer, M J; Stevens, M P; Narbad, A

2017-08-01

1. Campylobacter jejuni is the most common bacterial cause of human food-borne gastroenteritis in the world. A major source of human infection is the consumption of contaminated meat, particularly poultry. New control measures to reduce or eliminate this pathogen from the animal gastrointestinal tract are urgently required, and the use of probiotics as competitive exclusion agents is a promising biocontrol measure to reduce C. jejuni in the food chain. 2. In this study, we assessed the potential of Lactobacillus johnsonii FI9785, which has shown efficacy against Clostridium perfringens, to combat C. jejuni. The effect of prophylactic administration of L. johnsonii on the ability of C. jejuni to colonise chickens was determined. 3. Two doses of L. johnsonii given a week apart led to a reduction in C. jejuni colonisation in the caecal contents, but this biocontrol seemed reliant upon a high level of initial colonisation by the probiotic. 4. The microbial composition in the chicken gut was significantly altered by the probiotic treatment, as shown by denaturing gradient gel electrophoresis of 16S rRNA gene amplicons. 5. Together these results demonstrate the potential of this probiotic strain to be tested further as a competitive exclusion agent in poultry against C. jejuni.

Modification of the technical properties of Lactobacillus johnsonii NCC 533 by supplementing the growth medium with unsaturated fatty acids.

PubMed

Muller, J A; Ross, R P; Sybesma, W F H; Fitzgerald, G F; Stanton, C

2011-10-01

The aim of this study was to investigate the influence of supplementing growth medium with unsaturated fatty acids on the technical properties of the probiotic strain Lactobacillus johnsonii NCC 533, such as heat and acid tolerance, and inhibition of Salmonella enterica serovar Typhimurium infection. Our results showed that the membrane composition and morphology of L. johnsonii NCC 533 were significantly changed by supplementing a minimal Lactobacillus medium with oleic, linoleic, and linolenic acids. The ratio of saturated to unsaturated plus cyclic fatty acids in the bacterial membrane decreased by almost 2-fold when minimal medium was supplemented with unsaturated fatty acids (10 μg/ml). The subsequent acid and heat tolerance of L. johnsonii decreased by 6- and 20-fold when the strain was grown in the presence of linoleic and linolenic acids, respectively, compared with growth in oleic acid (all at 10 μg/ml). Following acid exposure, significantly higher (P < 0.05) oleic acid content was detected in the membrane when growth medium was supplemented with linoleic or linolenic acid, indicating that saturation of the membrane fatty acids occurred during acid stress. Cell integrity was determined in real time during stressed conditions using a fluorescent viability kit in combination with flow cytometric analysis. Following heat shock (at 62.5°C for 5 min), L. johnsonii was unable to form colonies; however, 60% of the bacteria showed no cell integrity loss, which could indicate that the elevated heat inactivated vital processes within the cell, rendering it incapable of replication. Furthermore, L. johnsonii grown in fatty acid-enriched minimal medium had different adhesion properties and caused a 2-fold decrease in S. enterica serovar Typhimurium UK1-lux invasion of HT-29 epithelial cells compared with bacteria grown in minimal medium alone. This could be related to changes in the hydrophobicity and fluidity of the membrane. Our study shows that technical

Modification of the Technical Properties of Lactobacillus johnsonii NCC 533 by Supplementing the Growth Medium with Unsaturated Fatty Acids ▿

PubMed Central

Muller, J. A.; Ross, R. P.; Sybesma, W. F. H.; Fitzgerald, G. F.; Stanton, C.

2011-01-01

The aim of this study was to investigate the influence of supplementing growth medium with unsaturated fatty acids on the technical properties of the probiotic strain Lactobacillus johnsonii NCC 533, such as heat and acid tolerance, and inhibition of Salmonella enterica serovar Typhimurium infection. Our results showed that the membrane composition and morphology of L. johnsonii NCC 533 were significantly changed by supplementing a minimal Lactobacillus medium with oleic, linoleic, and linolenic acids. The ratio of saturated to unsaturated plus cyclic fatty acids in the bacterial membrane decreased by almost 2-fold when minimal medium was supplemented with unsaturated fatty acids (10 μg/ml). The subsequent acid and heat tolerance of L. johnsonii decreased by 6- and 20-fold when the strain was grown in the presence of linoleic and linolenic acids, respectively, compared with growth in oleic acid (all at 10 μg/ml). Following acid exposure, significantly higher (P < 0.05) oleic acid content was detected in the membrane when growth medium was supplemented with linoleic or linolenic acid, indicating that saturation of the membrane fatty acids occurred during acid stress. Cell integrity was determined in real time during stressed conditions using a fluorescent viability kit in combination with flow cytometric analysis. Following heat shock (at 62.5°C for 5 min), L. johnsonii was unable to form colonies; however, 60% of the bacteria showed no cell integrity loss, which could indicate that the elevated heat inactivated vital processes within the cell, rendering it incapable of replication. Furthermore, L. johnsonii grown in fatty acid-enriched minimal medium had different adhesion properties and caused a 2-fold decrease in S. enterica serovar Typhimurium UK1-lux invasion of HT-29 epithelial cells compared with bacteria grown in minimal medium alone. This could be related to changes in the hydrophobicity and fluidity of the membrane. Our study shows that technical

Identification and Characterization of Novel Surface Proteins in Lactobacillus johnsonii and Lactobacillus gasseri

PubMed Central

Ventura, Marco; Jankovic, Ivana; Walker, D. Carey; Pridmore, R. David; Zink, Ralf

2002-01-01

We have identified and sequenced the genes encoding the aggregation-promoting factor (APF) protein from six different strains of Lactobacillus johnsonii and Lactobacillus gasseri. Both species harbor two apf genes, apf1 and apf2, which are in the same orientation and encode proteins of 257 to 326 amino acids. Multiple alignments of the deduced amino acid sequences of these apf genes demonstrate a very strong sequence conservation of all of the genes with the exception of their central regions. Northern blot analysis showed that both genes are transcribed, reaching their maximum expression during the exponential phase. Primer extension analysis revealed that apf1 and apf2 harbor a putative promoter sequence that is conserved in all of the genes. Western blot analysis of the LiCl cell extracts showed that APF proteins are located on the cell surface. Intact cells of L. johnsonii revealed the typical cell wall architecture of S-layer-carrying gram-positive eubacteria, which could be selectively removed with LiCl treatment. In addition, the amino acid composition, physical properties, and genetic organization were found to be quite similar to those of S-layer proteins. These results suggest that APF is a novel surface protein of the Lactobacillus acidophilus B-homology group which might belong to an S-layer-like family. PMID:12450842

Extending viability of Lactobacillus plantarum and Lactobacillus johnsonii by microencapsulation in alginate microgels.

PubMed

Tiani, Kendra A; Yeung, Timothy W; McClements, D Julian; Sela, David A

2018-03-01

To investigate whether microencapsulation of Lactobacillus in alginate microbeads will lead to increased longevity during refrigerated storage or simulated digestion. Microscopy was used to confirm that Lactobacillus plantarum ATCC BAA-793 and Lactobacillus johnsonii ATCC 33200 were immobilised within the microbeads and laser scattering analysis was used to determine the mean diameter of the microbeads. The number of viable cells were enumerated throughout refrigerated storage and simulated digestion experiments. Microencapsulation was shown to have differing effects on viability depending on the species, but led to extended viability during refrigerated storage and simulated digestion in L. johnsonii and L. plantarum respectively. Fermented functional foods contain microbes beneficial to human health. However, extended shelf storage and the harsh environment of the GI tract significantly reduces the number of viable microbes reaching the consumer. Microencapsulation allows beneficial microbes to reach the gut of the consumer in higher numbers, and thus confer greater health benefits.

Lactobacillus johnsonii glycolipids, their structure and immunoreactivity with sera from inflammatory bowel disease patients.

PubMed

Paściak, Mariola; Górska, Sabina; Jawiarczyk, Natalia; Gamian, Andrzej

2017-03-01

Structural studies of the major glycolipids produced by two Lactobacillus johnsonii (LJ) strains, LJ 151 isolated from intestinal tract of healthy mice and LJ 142 isolated from mice with experimentally induced inflammatory bowel disease (IBD), were performed. Two major glycolipids, GL1 and GL2, were present in lipid extracts from L. johnsonii 142 and 151 strains. Glycolipid GL1 has been identified as β-D-Glcp-(1→6)-α-D-Galp-(1→2)-α-D-Glcp-diglyceride and GL2 as α-D-Galp-(1→2)-α-D-Glcp-diglyceride. The main fatty acid residues identified by gas-liquid chromatography-mass spectrometry were palmitic, stearic and lactobacillic acids. Besides structural elucidation of the major glycolipids, the aim of this study was to determine the immunochemical properties of these glycolipids and to compare their immunoreactivity to that of polysaccharides obtained from the same strains. Sera from rabbits immunized with bacterial cells possessed much higher serological reactivity with polysaccharides than with glycolipids. Inversely, reactivity of the glycolipids with human sera from patients with IBD was much higher than that determined for the polysaccharides, while reactivity of glycolipids with human sera from healthy individuals was much lower than one measured for the polysaccharides. Results indicate that glycoconjugates from Lactobacillus cell wall act as antigens and may represent new IBD diagnostic biomarkers. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Identification of a mouse Lactobacillus johnsonii strain with deconjugase activity against the FXR antagonist T-β-MCA

PubMed Central

DiMarzio, Michael; Rusconi, Brigida; Yennawar, Neela H.; Eppinger, Mark; Patterson, Andrew D.

2017-01-01

Bile salt hydrolase (BSH) activity against the bile acid tauro-beta-muricholic acid (T-β-MCA) was recently reported to mediate host bile acid, glucose, and lipid homeostasis via the farnesoid X receptor (FXR) signaling pathway. An earlier study correlated decreased Lactobacillus abundance in the cecum with increased concentrations of intestinal T-β-MCA, an FXR antagonist. While several studies have characterized BSHs in lactobacilli, deconjugation of T-β-MCA remains poorly characterized among members of this genus, and therefore it was unclear what strain(s) were responsible for this activity. Here, a strain of L. johnsonii with robust BSH activity against T-β-MCA in vitro was isolated from the cecum of a C57BL/6J mouse. A screening assay performed on a collection of 14 Lactobacillus strains from nine different species identified BSH substrate specificity for T-β-MCA only in two of three L. johnsonii strains. Genomic analysis of the two strains with this BSH activity revealed the presence of three bsh genes that are homologous to bsh genes in the previously sequenced human-associated strain L. johnsonii NCC533. Heterologous expression of several bsh genes in E. coli followed by enzymatic assays revealed broad differences in substrate specificity even among closely related bsh homologs, and suggests that the phylogeny of these enzymes does not closely correlate with substrate specificity. Predictive modeling allowed us to propose a potential mechanism driving differences in BSH activity for T-β-MCA in these homologs. Our data suggests that L. johnsonii regulates T-β-MCA levels in the mouse intestinal environment, and that this species may play a central role in FXR signaling in the mouse. PMID:28910295

Identification of a mouse Lactobacillus johnsonii strain with deconjugase activity against the FXR antagonist T-β-MCA.

PubMed

DiMarzio, Michael; Rusconi, Brigida; Yennawar, Neela H; Eppinger, Mark; Patterson, Andrew D; Dudley, Edward G

2017-01-01

Bile salt hydrolase (BSH) activity against the bile acid tauro-beta-muricholic acid (T-β-MCA) was recently reported to mediate host bile acid, glucose, and lipid homeostasis via the farnesoid X receptor (FXR) signaling pathway. An earlier study correlated decreased Lactobacillus abundance in the cecum with increased concentrations of intestinal T-β-MCA, an FXR antagonist. While several studies have characterized BSHs in lactobacilli, deconjugation of T-β-MCA remains poorly characterized among members of this genus, and therefore it was unclear what strain(s) were responsible for this activity. Here, a strain of L. johnsonii with robust BSH activity against T-β-MCA in vitro was isolated from the cecum of a C57BL/6J mouse. A screening assay performed on a collection of 14 Lactobacillus strains from nine different species identified BSH substrate specificity for T-β-MCA only in two of three L. johnsonii strains. Genomic analysis of the two strains with this BSH activity revealed the presence of three bsh genes that are homologous to bsh genes in the previously sequenced human-associated strain L. johnsonii NCC533. Heterologous expression of several bsh genes in E. coli followed by enzymatic assays revealed broad differences in substrate specificity even among closely related bsh homologs, and suggests that the phylogeny of these enzymes does not closely correlate with substrate specificity. Predictive modeling allowed us to propose a potential mechanism driving differences in BSH activity for T-β-MCA in these homologs. Our data suggests that L. johnsonii regulates T-β-MCA levels in the mouse intestinal environment, and that this species may play a central role in FXR signaling in the mouse.

A Mesocosm of Lactobacillus johnsonii, Bifidobacterium longum, and Escherichia coli in the mouse gut.

PubMed

Denou, Emmanuel; Rezzonico, Enea; Panoff, Jean-Michel; Arigoni, Fabrizio; Brüssow, Harald

2009-08-01

The relative contribution of competition and cooperation at the microbe-microbe level is not well understood for the bacteria constituting the gut microbiota. The high number and variability of human gut commensals have hampered the analysis. To get some insight into the question how so many different bacterial species can coexist in the mammalian gut, we studied the interaction between three human gut commensals (Escherichia coli K-12, Lactobacillus johnsonii NCC533, and Bifidobacterium longum NCC2705) in the intestine of gnotobiotic mice. The bacterial titers and their anatomical distribution were studied in the colonized mice. L. johnsonii achieved the highest cell counts in the stomach, while B. longum dominated the colon. The colon was also the intestinal location in which B. longum displayed the highest number of expressed genes, followed by the cecum and the small intestine. Addition of further bacterial strains led to strikingly different results. A Lactobacillus paracasei strain coexisted, while a second B. longum strain was excluded from the system. Notably, this strain lacked an operon involved in the degradation, import, and metabolism of mannosylated glycans. Subsequent introduction of the E. coli Nissle strain resulted in the elimination of L. johnsonii NCC533 and E. coli K-12, while B. longum NCC2705 showed a transient decrease in population size, demonstrating the dynamic nature of microbe-microbe interactions. The study of such simple interacting bacterial systems might help to derive some basic rules governing microbial ecology within the mammalian gut.

Mosaic tetracycline resistance genes and their flanking regions in Bifidobacterium thermophilum and Lactobacillus johnsonii.

PubMed

van Hoek, Angela H A M; Mayrhofer, Sigrid; Domig, Konrad J; Flórez, Ana B; Ammor, Mohammed S; Mayo, Baltasar; Aarts, Henk J M

2008-01-01

For the first time, mosaic tetracycline resistance genes were identified in Lactobacillus johnsonii and in Bifidobacterium thermophilum strains. The L. johnsonii strain investigated contains a complex hybrid gene, tet(O/W/32/O/W/O), whereas the five bifidobacterial strains possess two different mosaic tet genes: i.e., tet(W/32/O) and tet(O/W). As reported by others, the crossover points of the mosaic tet gene segments were found at similar positions within the genes, suggesting a hot spot for recombination. Analysis of the sequences flanking these genes revealed that the upstream part corresponds to the 5' end of the mosaic open reading frame. In contrast, the downstream region was shown to be more variable. Surprisingly, in one of the B. thermophilum strains a third tet determinant was identified, coding for the efflux pump Tet(L).

Impact of the exopolysaccharide layer on biofilms, adhesion and resistance to stress in Lactobacillus johnsonii FI9785.

PubMed

Dertli, Enes; Mayer, Melinda J; Narbad, Arjan

2015-02-04

The bacterial cell surface is a crucial factor in cell-cell and cell-host interactions. Lactobacillus johnsonii FI9785 produces an exopolysaccharide (EPS) layer whose quantity and composition is altered in mutants that harbour genetic changes in their eps gene clusters. We have assessed the effect of changes in EPS production on cell surface characteristics that may affect the ability of L. johnsonii to colonise the poultry host and exclude pathogens. Analysis of physicochemical cell surface characteristics reflected by Zeta potential and adhesion to hexadecane showed that an increase in EPS gave a less negative, more hydrophilic surface and reduced autoaggregation. Autoaggregation was significantly higher in mutants that have reduced EPS, indicating that EPS can mask surface structures responsible for cell-cell interactions. EPS also affected biofilm formation, but here the quantity of EPS produced was not the only determinant. A reduction in EPS production increased bacterial adhesion to chicken gut explants, but made the bacteria less able to survive some stresses. This study showed that manipulation of EPS production in L. johnsonii FI9785 can affect properties which may improve its performance as a competitive exclusion agent, but that positive changes in adhesion may be compromised by a reduction in the ability to survive stress.

Primary administration of Lactobacillus johnsonii NCC533 in weaning period suppresses the elevation of proinflammatory cytokines and CD86 gene expressions in skin lesions in NC/Nga mice.

PubMed

Inoue, Ryo; Otsuka, Mai; Nishio, Ayako; Ushida, Kazunari

2007-06-01

The administration of probiotic lactic acid bacteria (LAB) has been studied for its potential to prevent atopic dermatitis (AD). The objective of this study was to assess the inhibitory mechanism of a skin lesion by LAB using an experimental model that we previously demonstrated in NC/Nga mice. Lactobacillus johnsonii NCC533 (La1) was administered orally to the La1 group from 20 to 22 days after birth, while phosphate-buffered saline was given to the control group. After the induction of skin lesions in 6-week-old mice, the expression of genes supposedly involved in AD was evaluated. Gene expression of the proinflammatory cytokines [interleukin-8 (IL-8), IL-12 and IL-23] was significantly enhanced in the lesional skin of the control group by the induction of the lesion, whereas gene expression of those in the La1 group was not elevated. Interestingly, expression of the costimulatory molecule CD86 showed a pattern similar to the expression of the cytokines in the lesional skin. Moreover, the La1 group showed a significantly lower gene expression of CD86 in Peyer's patches and mesenteric lymph nodes than the control group. The suppression of proinflammatory cytokines and CD86 by primary administration of La1 may significantly contribute to the inhibitory effect on the skin lesion.

Effect of a lotion containing the heat-treated probiotic strain Lactobacillus johnsonii NCC 533 on Staphylococcus aureus colonization in atopic dermatitis.

PubMed

Blanchet-Réthoré, Sandrine; Bourdès, Valérie; Mercenier, Annick; Haddar, Cyrille H; Verhoeven, Paul O; Andres, Philippe

2017-01-01

Staphylococcus aureus dominates the skin microbiota in patients with atopic dermatitis (AD), with bacterial loads correlating with disease severity. The aim of this exploratory study was to investigate the effect of a cosmetic lotion containing heat-treated Lactobacillus johnsonii NCC 533 (HT La1) on S. aureus colonization in AD patients. This open-label, multicenter study was performed in AD patients in Germany. First, detection of S. aureus was performed in all patients using the swab or scrub-wash method of sampling, followed by quantitative culture or quantitative polymerase chain reaction. Repeatability and reproducibility of all method combinations were evaluated to select the best combination of sampling and quantification. Second, a lotion containing HT La1 was applied to lesional skin twice daily for 3 weeks. Scoring using local objective SCORing Atopic Dermatitis (SCORAD), measurement of S. aureus load, and lesional microbiome analysis were performed before and after the 3-week treatment period. Thirty-one patients with AD were included in the study. All sampling and quantification methods were found to be robust, reproducible, and repeatable for assessing S. aureus load. For simplicity, a combination of swab and quantitative polymerase chain reaction was chosen to assess the efficacy of HT La1. Following application of a lotion containing HT La1 to AD lesions for 3 weeks, a reduction in S. aureus load was observed in patients, which correlated with a decrease in local objective SCORAD. Interestingly, high baseline skin concentrations of S. aureus were associated with good responses to the lotion. This study demonstrated that the application of a lotion containing HT La1 to the lesional skin of patients with AD for 3 weeks controlled S. aureus colonization and was associated with local clinical improvement (SCORAD). These findings support further development of topical treatments containing heat-treated nonreplicating beneficial bacteria for patients with

The probiotic Lactobacillus johnsonii NCC 533 produces high-molecular-mass inulin from sucrose by using an inulosucrase enzyme.

PubMed

Anwar, Munir A; Kralj, Slavko; van der Maarel, Marc J E C; Dijkhuizen, Lubbert

2008-06-01

Fructansucrase enzymes polymerize the fructose moiety of sucrose into levan or inulin fructans, with beta(2-6) and beta(2-1) linkages, respectively. The probiotic bacterium Lactobacillus johnsonii strain NCC 533 possesses a single fructansucrase gene (open reading frame AAS08734) annotated as a putative levansucrase precursor. However, (13)C nuclear magnetic resonance (NMR) analysis of the fructan product synthesized in situ revealed that this is of the inulin type. The ftf gene of L. johnsonii was cloned and expressed to elucidate its exact identity. The purified L. johnsonii protein was characterized as an inulosucrase enzyme, producing inulin from sucrose, as identified by (13)C NMR analysis. Thin-layer chromatographic analysis of the reaction products showed that InuJ synthesized, besides the inulin polymer, a broad range of fructose oligosaccharides. Maximum InuJ enzyme activity was observed in a pH range of 4.5 to 7.0, decreasing sharply at pH 7.5. InuJ exhibited the highest enzyme activity at 55 degrees C, with a drastic decrease at 60 degrees C. Calcium ions were found to have an important effect on enzyme activity and stability. Kinetic analysis showed that the transfructosylation reaction of the InuJ enzyme does not obey Michaelis-Menten kinetics. The non-Michaelian behavior of InuJ may be attributed to the oligosaccharides that were initially formed in the reaction and which may act as better acceptors than the growing polymer chain. This is only the second example of the isolation and characterization of an inulosucrase enzyme and its inulin (oligosaccharide) product from a Lactobacillus strain. Furthermore, this is the first Lactobacillus strain shown to produce inulin polymer in situ.

A topical treatment containing heat-treated Lactobacillus johnsonii NCC 533 reduces Staphylococcus aureus adhesion and induces antimicrobial peptide expression in an in vitro reconstructed human epidermis model.

PubMed

Rosignoli, Carine; Thibaut de Ménonville, Séverine; Orfila, Danielle; Béal, Méline; Bertino, Béatrice; Aubert, Jérôme; Mercenier, Annick; Piwnica, David

2018-04-01

Staphylococcus aureus colonization is thought to contribute to the pathophysiology of atopic dermatitis (AD). AD patients exhibit reduced levels of cutaneous antimicrobial peptides (AMPs), which may explain their increased susceptibility to infections. Using an in vitro reconstructed human epidermis (RHE) model, we sought to determine whether topical application of a non-replicating probiotic, heat-treated Lactobacillus johnsonii NCC 533 (HT La1), could inhibit S. aureus adhesion to skin and boost cutaneous innate immunity. We found that application of HT La1 suspension to RHE samples reduced the binding of radiolabelled S. aureus by up to 74%. To investigate a potential effect of HT La1 on innate immunity, we analysed the expression of nine AMP genes, including those encoding beta defensins and S100 proteins, following topical application of HT La1 in suspension or in a daily moisturizer lotion. Analysed genes were induced by up to fourfold in a dose-dependent manner by HT La1 in suspension and by up to 2.4-fold by HT La1 in the moisturizer lotion. Finally, using ELISA and immunohistochemical detection, we evaluated the expression and secretion of the AMPs hBD-2 and psoriasin and determined that both proteins were induced by topical HT La1, particularly in the stratum corneum of the RHE. These findings demonstrate that a topically applied, non-replicating probiotic can modulate endogenous AMP expression and inhibit binding of S. aureus to an RHE model in vitro. Moreover, they suggest that a topical formulation containing HT La1 could benefit atopic skin by enhancing cutaneous innate immunity and reducing S. aureus colonization. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Efficacy of combined or single use of Lactobacillus crispatus LT116 and L. johnsonii LT171 on broiler performance.

PubMed

Taheri, H R; Moravej, H; Tabandeh, F; Zaghari, M; Shivazad, M

2010-10-01

1. The objective of this research was to investigate the efficacy of combined or single use of Lactobacillus crispatus LT116 and Lactobacillus johnsonii LT171 on broiler performance. 2. A total of 320 one-d-old male Ross broiler chicks were allocated in 4 experimental treatments for 6 weeks. The experimental treatments received a maize-soybean meal basal diet that was supplemented as follows: 'control', with no other additions; 'LJ', 1 × 10(6) CFU of L. johnsonii LT171; 'LC', 1 × 10(6) CFU of L. crispatus LT116; and 'LCJ', 0·5 × 10(6) CFU of L. johnsonii LT171 + 0·5 × 10(6) CFU of L. crispatus LT116/g of the diet. A suspension of sheep red blood cells (SRBC) was injected into the breast of 8 birds from each treatment on d 14 and 30, and the antibody titre was measured on d 20, 26, 36 and 42. 3. Body weight was improved when compared with control for broilers fed diets supplemented with LCJ. The feed conversion ratio (FCR) decreased in LC and LCJ groups compared with control. The number of coliforms in the ileum of LJ, LC and LCJ birds was lower than that from the control birds. However, only the LCJ treatment significantly decreased the number of coliforms in the caecum. The LCJ group had greater villus height in the duodenum than the LC group, and both LCJ and LC groups showed increased villus height in the duodenum and jejunum relative to the control. Antibody titre against SRBC was higher for the LCJ group than for the LJ and control groups in terms of secondary immune response (mean of 36 and 42 d). 4. This study showed, compared with the control, that the combination of Lactobacillus spp. could positively affect body weight, coliform numbers in the caecum and immune response.

Hydrolysis of rosmarinic acid from rosemary extract with esterases and Lactobacillus johnsonii in vitro and in a gastrointestinal model.

PubMed

Bel-Rhlid, Rachid; Crespy, Vanessa; Pagé-Zoerkler, Nicole; Nagy, Kornél; Raab, Thomas; Hansen, Carl-Erik

2009-09-09

Rosmarinic acid (RA) was identified as one of the main components of rosemary extracts and has been ascribed to a number of health benefits. Several studies suggested that after ingestion, RA is metabolized by gut microflora into caffeic acid and derivatives. However, only limited information on the microorganisms and enzymes involved in this biotransformation is available. In this study, we investigated the hydrolysis of RA from rosemary extract with enzymes and a probiotic bacterium Lactobacillus johnsonii NCC 533. Chlorogenate esterase from Aspergillus japonicus (0.02 U/mg) hydrolyzed 90% of RA (5 mg/mL) after 2 h at pH 7.0 and 40 degrees C. Complete hydrolysis of RA (5 mg/mL) was achieved with a preparation of L. johnsonii (25 mg/mL, 3.3 E9 cfu/g) after 2 h of incubation at pH 7.0 and 37 degrees C. No hydrolysis of RA was observed after the passage of rosemary extract through the gastrointestinal tract model (GI model). Thus, RA is hydrolyzed neither chemically under the conditions of the GI model (temperature, pH, and bile salts) nor by secreted enzymatic activity (lipase and pancreatic enzymes). The addition of L. johnsonii cells to rosemary extract in the GI model resulted in substantial hydrolysis of RA (up to 99%).

Effect of Lactobacillus johnsonii CRL1647 on different parameters of honeybee colonies and bacterial populations of the bee gut.

PubMed

Audisio, M C; Sabaté, D C; Benítez-Ahrendts, M R

2015-01-01

Lactobacillus johnsonii CRL1647, isolated from the intestinal tract of a worker-bee in Salta, Argentina, was delivered to Apis mellifera L. honey bee colonies according to two different administration schedules: 1×10(5) cfu/ml every 15 days (2011) or monthly (2012). The effect of each treatment on the bee-colony performance was monitored by measuring honey production, and the prevalence of varroasis and nosemosis. Worker bees from each assay were randomly captured 3 days after administration and assayed for the following intestinal culturable and defined bacterial populations: total aerobic microorganisms, Bacillus spp. spores, Lactobacillus spp., Enterococcus spp. and enterobacteria. Interestingly, both treatments generated a similar increase in honey production in treated colonies compared to controls: 36.8% (every 15 days) and 36.3% (monthly). Nosema index always exhibited a reduction when lactobacilli were administered; in turn, Varroa incidence was lower when the lactobacilli were administered once a month. Moreover, the administration of L. johnsonii CRL1647 every 15 days produced an increase in the total number of aerobic microorganisms and in bacteria belonging to the genera Lactobacillus and Enterococcus; at the same time, a decrease was observed in the number of total spores at the end of the treatment. The number of enterobacteria was constant and remained below that of control hives at the end of the assay. On the other hand, the delivery of lactobacilli once a month only showed an increase in the number of bacteria belonging to the genus Lactobacillus; meanwhile, viable counts of the remaining microorganisms assayed were reduced. Even though it seems that both treatments were similar, those bee colonies that received L. johnsonii CRL1647 every 15 days became so strong that they swarmed.

Effects of Lactobacillus johnsonii and Lactobacillus reuteri on gut barrier function and heat shock proteins in intestinal porcine epithelial cells.

PubMed

Liu, Hao-Yu; Roos, Stefan; Jonsson, Hans; Ahl, David; Dicksved, Johan; Lindberg, Jan Erik; Lundh, Torbjörn

2015-04-01

Heat shock proteins (HSPs) are a set of highly conserved proteins that can serve as intestinal gate keepers in gut homeostasis. Here, effects of a probiotic, Lactobacillus rhamnosus GG (LGG), and two novel porcine isolates, Lactobacillus johnsonii strain P47-HY and Lactobacillus reuteri strain P43-HUV, on cytoprotective HSP expression and gut barrier function, were investigated in a porcine IPEC-J2 intestinal epithelial cell line model. The IPEC-J2 cells polarized on a permeable filter exhibited villus-like cell phenotype with development of apical microvilli. Western blot analysis detected HSP expression in IPEC-J2 and revealed that L. johnsonii and L. reuteri strains were able to significantly induce HSP27, despite high basal expression in IPEC-J2, whereas LGG did not. For HSP72, only the supernatant of L. reuteri induced the expression, which was comparable to the heat shock treatment, which indicated that HSP72 expression was more stimulus specific. The protective effect of lactobacilli was further studied in IPEC-J2 under an enterotoxigenic Escherichia coli (ETEC) challenge. ETEC caused intestinal barrier destruction, as reflected by loss of cell-cell contact, reduced IPEC-J2 cell viability and transepithelial electrical resistance, and disruption of tight junction protein zonula occludens-1. In contrast, the L. reuteri treatment substantially counteracted these detrimental effects and preserved the barrier function. L. johnsonii and LGG also achieved barrier protection, partly by directly inhibiting ETEC attachment. Together, the results indicate that specific strains of Lactobacillus can enhance gut barrier function through cytoprotective HSP induction and fortify the cell protection against ETEC challenge through tight junction protein modulation and direct interaction with pathogens. © 2015 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Effects of Lactobacillus johnsonii and Lactobacillus reuteri on gut barrier function and heat shock proteins in intestinal porcine epithelial cells

PubMed Central

Liu, Hao-Yu; Roos, Stefan; Jonsson, Hans; Ahl, David; Dicksved, Johan; Lindberg, Jan Erik; Lundh, Torbjörn

2015-01-01

Heat shock proteins (HSPs) are a set of highly conserved proteins that can serve as intestinal gate keepers in gut homeostasis. Here, effects of a probiotic, Lactobacillus rhamnosus GG (LGG), and two novel porcine isolates, Lactobacillus johnsonii strain P47-HY and Lactobacillus reuteri strain P43-HUV, on cytoprotective HSP expression and gut barrier function, were investigated in a porcine IPEC-J2 intestinal epithelial cell line model. The IPEC-J2 cells polarized on a permeable filter exhibited villus-like cell phenotype with development of apical microvilli. Western blot analysis detected HSP expression in IPEC-J2 and revealed that L. johnsonii and L. reuteri strains were able to significantly induce HSP27, despite high basal expression in IPEC-J2, whereas LGG did not. For HSP72, only the supernatant of L. reuteri induced the expression, which was comparable to the heat shock treatment, which indicated that HSP72 expression was more stimulus specific. The protective effect of lactobacilli was further studied in IPEC-J2 under an enterotoxigenic Escherichia coli (ETEC) challenge. ETEC caused intestinal barrier destruction, as reflected by loss of cell–cell contact, reduced IPEC-J2 cell viability and transepithelial electrical resistance, and disruption of tight junction protein zonula occludens-1. In contrast, the L. reuteri treatment substantially counteracted these detrimental effects and preserved the barrier function. L. johnsonii and LGG also achieved barrier protection, partly by directly inhibiting ETEC attachment. Together, the results indicate that specific strains of Lactobacillus can enhance gut barrier function through cytoprotective HSP induction and fortify the cell protection against ETEC challenge through tight junction protein modulation and direct interaction with pathogens. PMID:25847917

Fecal Microbiota Transplantation, Commensal Escherichia coli and Lactobacillus johnsonii Strains Differentially Restore Intestinal and Systemic Adaptive Immune Cell Populations Following Broad-spectrum Antibiotic Treatment.

PubMed

Ekmekciu, Ira; von Klitzing, Eliane; Neumann, Christian; Bacher, Petra; Scheffold, Alexander; Bereswill, Stefan; Heimesaat, Markus M

2017-01-01

The essential role of the intestinal microbiota in the well-functioning of host immunity necessitates the investigation of species-specific impacts on this interplay. Aim of this study was to examine the ability of defined Gram-positive and Gram-negative intestinal commensal bacterial species, namely Escherichia coli and Lactobacillus johnsonii , respectively, to restore immune functions in mice that were immunosuppressed by antibiotics-induced microbiota depletion. Conventional mice were subjected to broad-spectrum antibiotic treatment for 8 weeks and perorally reassociated with E. coli , L. johnsonii or with a complex murine microbiota by fecal microbiota transplantation (FMT). Analyses at days (d) 7 and 28 revealed that immune cell populations in the small and large intestines, mesenteric lymph nodes and spleens of mice were decreased after antibiotic treatment but were completely or at least partially restored upon FMT or by recolonization with the respective bacterial species. Remarkably, L. johnsonii recolonization resulted in the highest CD4+ and CD8+ cell numbers in the small intestine and spleen, whereas neither of the commensal species could stably restore those cell populations in the colon until d28. Meanwhile less efficient than FMT, both species increased the frequencies of regulatory T cells and activated dendritic cells and completely restored intestinal memory/effector T cell populations at d28. Furthermore, recolonization with either single species maintained pro- and anti-inflammatory immune functions in parallel. However, FMT could most effectively recover the decreased frequencies of cytokine producing CD4+ lymphocytes in mucosal and systemic compartments. E. coli recolonization increased the production of cytokines such as TNF, IFN-γ, IL-17, and IL-22, particularly in the small intestine. Conversely, only L. johnsonii recolonization maintained colonic IL-10 production. In summary, FMT appears to be most efficient in the restoration of

Fecal Microbiota Transplantation, Commensal Escherichia coli and Lactobacillus johnsonii Strains Differentially Restore Intestinal and Systemic Adaptive Immune Cell Populations Following Broad-spectrum Antibiotic Treatment

PubMed Central

Ekmekciu, Ira; von Klitzing, Eliane; Neumann, Christian; Bacher, Petra; Scheffold, Alexander; Bereswill, Stefan; Heimesaat, Markus M.

2017-01-01

The essential role of the intestinal microbiota in the well-functioning of host immunity necessitates the investigation of species-specific impacts on this interplay. Aim of this study was to examine the ability of defined Gram-positive and Gram-negative intestinal commensal bacterial species, namely Escherichia coli and Lactobacillus johnsonii, respectively, to restore immune functions in mice that were immunosuppressed by antibiotics-induced microbiota depletion. Conventional mice were subjected to broad-spectrum antibiotic treatment for 8 weeks and perorally reassociated with E. coli, L. johnsonii or with a complex murine microbiota by fecal microbiota transplantation (FMT). Analyses at days (d) 7 and 28 revealed that immune cell populations in the small and large intestines, mesenteric lymph nodes and spleens of mice were decreased after antibiotic treatment but were completely or at least partially restored upon FMT or by recolonization with the respective bacterial species. Remarkably, L. johnsonii recolonization resulted in the highest CD4+ and CD8+ cell numbers in the small intestine and spleen, whereas neither of the commensal species could stably restore those cell populations in the colon until d28. Meanwhile less efficient than FMT, both species increased the frequencies of regulatory T cells and activated dendritic cells and completely restored intestinal memory/effector T cell populations at d28. Furthermore, recolonization with either single species maintained pro- and anti-inflammatory immune functions in parallel. However, FMT could most effectively recover the decreased frequencies of cytokine producing CD4+ lymphocytes in mucosal and systemic compartments. E. coli recolonization increased the production of cytokines such as TNF, IFN-γ, IL-17, and IL-22, particularly in the small intestine. Conversely, only L. johnsonii recolonization maintained colonic IL-10 production. In summary, FMT appears to be most efficient in the restoration of

Eradication of Helicobacter pylori infection by the probiotic strains Lactobacillus johnsonii MH-68 and L. salivarius ssp. salicinius AP-32.

PubMed

Hsieh, Pei-Shan; Tsai, Yi-Chun; Chen, Yi-Chun; Teh, Su-Fen; Ou, Chung-Mou; King, V An-Erl

2012-12-01

The current therapy for Helicobacter pylori infection includes antimicrobial agents and proton pump inhibitors. We have examined the ability of Lactobacillus spp. to inhibit H. pylori infection. Probiotic strains isolated from samples of adult feces, infant feces, breast milk, and vaginal swab collected from healthy volunteers in Taiwan and commercially available strains were screened for antagonism toward H. pylori. Inhibition liquid culture assay was used to screen potential anti-H. pylori activity. Then, we performed agar plate inhibition assay, and assays to determine the capacity of probiotics for adhesion, and inhibition and killing of H. pylori, and measured the levels of IL-8 and IL-10. Using animal models, we studied regulation of gastric acid and histopathological changes accompanying anti-H. pylori activity. We found that six of the tested strains suppressed urease activity of H. pylori: Lactobacillus acidophilus TYCA08, L. acidophilus TYCA15, L. johnsonii MH-68, and L. salivarius subsp. salicinius AP-32 were more effective than the others. In vivo, L. johnsonii MH-68 and L. salivarius subsp. salicinius AP-32 alone or in combination, reduced the H. pylori load in the gastric mucosa, and also reduced inflammatory chemokine expression and lymphocyte infiltration. Lactobacillus johnsonii MH-68 and L. salivarius subsp. salicinius AP-32 effectively suppress H. pylori viability, and when used as probiotics, they may help decrease the occurrence of gastritis, and even reduce the risk of H. pylori infection. © 2012 Blackwell Publishing Ltd.

Spontaneous mutation reveals influence of exopolysaccharide on Lactobacillus johnsonii surface characteristics.

PubMed

Horn, Nikki; Wegmann, Udo; Dertli, Enes; Mulholland, Francis; Collins, Samuel R A; Waldron, Keith W; Bongaerts, Roy J; Mayer, Melinda J; Narbad, Arjan

2013-01-01

As a competitive exclusion agent, Lactobacillus johnsonii FI9785 has been shown to prevent the colonization of selected pathogenic bacteria from the chicken gastrointestinal tract. During growth of the bacterium a rare but consistent emergence of an altered phenotype was noted, generating smooth colonies in contrast to the wild type rough form. A smooth colony variant was isolated and two-dimensional gel analysis of both strains revealed a protein spot with different migration properties in the two phenotypes. The spot in both gels was identified as a putative tyrosine kinase (EpsC), associated with a predicted exopolysaccharide gene cluster. Sequencing of the epsC gene from the smooth mutant revealed a single substitution (G to A) in the coding strand, resulting in the amino acid change D88N in the corresponding gene product. A native plasmid of L. johnsonii was engineered to produce a novel vector for constitutive expression and this was used to demonstrate that expression of the wild type epsC gene in the smooth mutant produced a reversion to the rough colony phenotype. Both the mutant and epsC complemented strains had increased levels of exopolysaccharides compared to the wild type strain, indicating that the rough phenotype is not solely associated with the quantity of exopolysaccharide. Another gene in the cluster, epsE, that encoded a putative undecaprenyl-phosphate galactosephosphotransferase, was deleted in order to investigate its role in exopolysaccharide biosynthesis. The ΔepsE strain exhibited a large increase in cell aggregation and a reduction in exopolysaccharide content, while plasmid complementation of epsE restored the wild type phenotype. Flow cytometry showed that the wild type and derivative strains exhibited clear differences in their adhesive ability to HT29 monolayers in tissue culture, demonstrating an impact of EPS on surface properties and bacteria-host interactions.

Spontaneous Mutation Reveals Influence of Exopolysaccharide on Lactobacillus johnsonii Surface Characteristics

PubMed Central

Horn, Nikki; Wegmann, Udo; Dertli, Enes; Mulholland, Francis; Collins, Samuel R. A.; Waldron, Keith W.; Bongaerts, Roy J.; Mayer, Melinda J.; Narbad, Arjan

2013-01-01

As a competitive exclusion agent, Lactobacillus johnsonii FI9785 has been shown to prevent the colonization of selected pathogenic bacteria from the chicken gastrointestinal tract. During growth of the bacterium a rare but consistent emergence of an altered phenotype was noted, generating smooth colonies in contrast to the wild type rough form. A smooth colony variant was isolated and two-dimensional gel analysis of both strains revealed a protein spot with different migration properties in the two phenotypes. The spot in both gels was identified as a putative tyrosine kinase (EpsC), associated with a predicted exopolysaccharide gene cluster. Sequencing of the epsC gene from the smooth mutant revealed a single substitution (G to A) in the coding strand, resulting in the amino acid change D88N in the corresponding gene product. A native plasmid of L. johnsonii was engineered to produce a novel vector for constitutive expression and this was used to demonstrate that expression of the wild type epsC gene in the smooth mutant produced a reversion to the rough colony phenotype. Both the mutant and epsC complemented strains had increased levels of exopolysaccharides compared to the wild type strain, indicating that the rough phenotype is not solely associated with the quantity of exopolysaccharide. Another gene in the cluster, epsE, that encoded a putative undecaprenyl-phosphate galactosephosphotransferase, was deleted in order to investigate its role in exopolysaccharide biosynthesis. The ΔepsE strain exhibited a large increase in cell aggregation and a reduction in exopolysaccharide content, while plasmid complementation of epsE restored the wild type phenotype. Flow cytometry showed that the wild type and derivative strains exhibited clear differences in their adhesive ability to HT29 monolayers in tissue culture, demonstrating an impact of EPS on surface properties and bacteria-host interactions. PMID:23544114

Preventing subclinical necrotic enteritis through Lactobacillus johnsonii BS15 by ameliorating lipid metabolism and intestinal microflora in broiler chickens.

PubMed

Qing, Xiaodan; Zeng, Dong; Wang, Hesong; Ni, Xueqin; Liu, Lei; Lai, Jing; Khalique, Abdul; Pan, Kangcheng; Jing, Bo

2017-12-01

Increasing studies have focused on the beneficial effects of Lactobacillus johnsonii in certain diseases. Here, we studied the prevention ability of a probiotic strain, L. johnsonii BS15 on subclinical necrotic enteritis (SNE), and its underlying mechanism. 180 male Cobb 500 chicks were randomly allotted into three groups and administrated with BS15 (1 × 10 6 cfu/g) or Man Rogosa Sharpe liquid medium throughout a 28-day experimental period. With the exception of the normal group, SNE infection was treated for the remaining experimental period after the chicks were fed with normal diet 14 days. Results showed that BS15 notably suppressed the SNE-induced loss of average daily gain and liver functional abnormality. Additionally, BS15 facilitated lipid metabolism of SNE boilers when the contents of peroxisome proliferator activated receptor γ and adipose triglyceride lipase in adipose tissue and serum high-density lipoprotein cholesterol decreased. BS15 also attenuated the hepatic lipid accumulation of stricken chicks by suppressing the genes expression of acetyl-CoA carboxylase, fatty acid synthase and sterol regulatory element binding protein-1c as well as stimulating the genes expression of peroxisome proliferator activated receptor α and carnitine palmitoyltransferase-1. Moreover, BS15 enhanced the development of SNE gut by improving the intestinal development and digestion as well as adjusting the gut microflora. Therefore, BS15 may provide a promising natural preventative strategy against SNE, which may be contributed to the amelioration of lipid metabolism and intestinal microflora.

Inhibition of type 1 diabetes correlated to a Lactobacillus johnsonii N6.2-mediated Th17 bias.

PubMed

Lau, Kenneth; Benitez, Patrick; Ardissone, Alexandria; Wilson, Tenisha D; Collins, Erin L; Lorca, Graciela; Li, Nan; Sankar, Dhyana; Wasserfall, Clive; Neu, Josef; Atkinson, Mark A; Shatz, Desmond; Triplett, Eric W; Larkin, Joseph

2011-03-15

Although it is known that resident gut flora contribute to immune system function and homeostasis, their role in the progression of the autoimmune disease type 1 diabetes (T1D) is poorly understood. Comparison of stool samples isolated from Bio-Breeding rats, a classic model of T1D, shows that distinct bacterial populations reside in spontaneous Bio-Breeding diabetes-prone (BBDP) and Bio-Breeding diabetes-resistant animals. We have previously shown that the oral transfer of Lactobacillus johnsonii strain N6.2 (LjN6.2) from Bio-Breeding diabetes-resistant to BBDP rodents conferred T1D resistance to BBDP rodents, whereas Lactobacillus reuteri strain TD1 did not. In this study, we show that diabetes resistance in LjN6.2-fed BBDP rodents was correlated to a Th17 cell bias within the mesenteric lymph nodes. The Th17 bias was not observed in the non-gut-draining axillary lymph nodes, suggesting that the Th17 bias was because of immune system interactions with LjN6.2 within the mesenteric lymph node. LjN6.2 interactions with the immune system were observed in the spleens of diabetes-resistant, LjN6.2-fed BBDP rats, as they also possessed a Th17 bias in comparison with control or Lactobacillus reuteri strain TD1-fed rats. Using C57BL/6 mouse in vitro assays, we show that LjN6.2 directly mediated enhanced Th17 differentiation of lymphocytes in the presence of TCR stimulation, which required APCs. Finally, we show that footpad vaccination of NOD mice with LjN6.2-pulsed dendritic cells was sufficient to mediate a Th17 bias in vivo. Together, these data suggest an interesting paradigm whereby T1D induction can be circumvented by gut flora-mediated Th17 differentiation.

Lactobacillus johnsonii HY7042 ameliorates Gardnerella vaginalis-induced vaginosis by killing Gardnerella vaginalis and inhibiting NF-κB activation.

PubMed

Joo, Hyun-Min; Hyun, Yang-Jin; Myoung, Kil-Sun; Ahn, Young-Tae; Lee, Jung-Hee; Huh, Chul-Sung; Han, Myung Joo; Kim, Dong-Hyun

2011-11-01

Hydrogen peroxide-producing lactic acid bacteria (LAB) were isolated from women's vaginas and their anti-inflammatory effects against Gardnerella vaginalis-induced vaginosis were examined in β-estradiol-immunosuppressed mice. Oral and intravaginal treatment with five LABs significantly decreased viable G. vaginalis numbers in vaginal cavities and myeloperoxidase activity in mouse vaginal tissues. Of the LABs examined, Lactobacillus johnsonii HY7042 (LJ) most potently inhibited G. vaginalis-induced vaginosis. This LAB also inhibited the expressions of IL-1β, IL-6, TNF-α, COX-2, and iNOS, and the activation of NF-κB in vaginal tissues, but increased IL-10 expression. Orally administered LJ (0.2×10(8) CFU/mouse) also inhibited the expression of TNF-α by 91.7% in β-estradiol-immunosuppressed mice intraperitoneally injected with LPS. However, it increased IL-10 expression by 63.3% in these mice. Furthermore, LJ inhibited the expressions of the pro-inflammatory cytokines, TNF-α and IL-1β, and the activation of NF-κB in lipopolysaccharide-stimulated peritoneal macrophages. LJ also killed G. vaginalis attached with and without HeLa cells. These findings suggest that LJ inhibits bacterial vaginosis by inhibiting the expressions of COX-2, iNOS, IL-1β, and TNF-α by regulating NF-κB activation and by killing G. vaginalis, and that LJ could ameliorate bacterial vaginosis. Copyright © 2011 Elsevier B.V. All rights reserved.

Co-biodegradation of anthracene and naphthalene by the bacterium Acinetobacter johnsonii.

PubMed

Jiang, Yan; Qi, Hui; Zhang, Xian M

2018-04-16

NAP (Naphthalene) and ANT (anthracene) usually co-exist in environment and possessed interactional effects on their biodegradation in environment. Presently, a strain of Acinetobacter johnsonii was employed to degrade NAP and ANT in single- and dual-substrate systems. NAP was utilized as prefer substrate by cells to accelerate ANT biodegradation. As much as 200 mg L -1 ANT could be entirely degraded with 1,500 mg L -1 NAP, which was beyond bacterial potential in single substrate system. Especially, the shortest biodegradation period (103 h) for ANT was observed with the presence of 50 mg L -1 NAP. By contrast, ANT showed strong inhibition on NAP degradation, while the peak biodegradation of 1,950 mg L -1 NAP with 50 mg L -1 ANT could still proceed. By introducing an inhibition constant parameter to fit the inhibition on cells, modeling indicated the substrate inhibition for NAP and ANT over the concentrations of 174 and 49 mg L -1 , respectively. Furthermore, enzyme assay revealed the pathway of meta fission in NAP biodegradation due to the appearance of catechol 2,3-dioxygenase activity, and low-level lipase excretion was also found in both NAP and ANT biodegradation, but hardly affect NAP and ANT biodegradation in the present study. To research the interplay of NAP and ANT is conducive to targeted decontamination.

H2O2 production rate in Lactobacillus johnsonii is modulated via the interplay of a heterodimeric flavin oxidoreductase with a soluble 28 Kd PAS domain containing protein

PubMed Central

Valladares, Ricardo B.; Graves, Christina; Wright, Kaitlyn; Gardner, Christopher L.; Lorca, Graciela L.; Gonzalez, Claudio F.

2015-01-01

Host and commensals crosstalk, mediated by reactive oxygen species (ROS), has triggered a growing scientific interest to understand the mechanisms governing such interaction. However, the majority of the scientific studies published do not evaluate the ROS production by commensals bacteria. In this context we recently showed that Lactobacillus johnsonii N6.2, a strain of probiotic value, modulates the activity of the critical enzymes 2,3-indoleamine dioxygenase via H2O2 production. L. johnsonii N6.2 by decreasing IDO activity, is able to modify the tryptophan/kynurenine ratio in the host blood with further systemic consequences. Understanding the mechanisms of H2O2 production is critical to predict the probiotic value of these strains and to optimize bacterial biomass production in industrial processes. We performed a transcriptome analysis to identify genes differentially expressed in L. johnsonii N6.2 cells collected from cultures grown under different aeration conditions. Herein we described the biochemical characteristics of a heterodimeric FMN reductase (FRedA/B) whose in vitro activity is controlled by LjPAS protein with a typical Per-Arnst-Sim (PAS) sensor domain. Interestingly, LjPAS is fused to the FMN reductase domains in other lactobacillaceae. In L. johnsonii, LjPAS is encoded by an independent gene which expression is repressed under anaerobic conditions (>3 fold). Purified LjPAS was able to slow down the FRedA/B initial activity rate when the holoenzyme precursors (FredA, FredB, and FMN) were mixed in vitro. Altogether the results obtained suggest that LjPAS module regulates the H2O2 production helping the cells to minimize oxidative stress in response to environmental conditions. PMID:26236298

H2O2 production rate in Lactobacillus johnsonii is modulated via the interplay of a heterodimeric flavin oxidoreductase with a soluble 28 Kd PAS domain containing protein.

PubMed

Valladares, Ricardo B; Graves, Christina; Wright, Kaitlyn; Gardner, Christopher L; Lorca, Graciela L; Gonzalez, Claudio F

2015-01-01

Host and commensals crosstalk, mediated by reactive oxygen species (ROS), has triggered a growing scientific interest to understand the mechanisms governing such interaction. However, the majority of the scientific studies published do not evaluate the ROS production by commensals bacteria. In this context we recently showed that Lactobacillus johnsonii N6.2, a strain of probiotic value, modulates the activity of the critical enzymes 2,3-indoleamine dioxygenase via H2O2 production. L. johnsonii N6.2 by decreasing IDO activity, is able to modify the tryptophan/kynurenine ratio in the host blood with further systemic consequences. Understanding the mechanisms of H2O2 production is critical to predict the probiotic value of these strains and to optimize bacterial biomass production in industrial processes. We performed a transcriptome analysis to identify genes differentially expressed in L. johnsonii N6.2 cells collected from cultures grown under different aeration conditions. Herein we described the biochemical characteristics of a heterodimeric FMN reductase (FRedA/B) whose in vitro activity is controlled by LjPAS protein with a typical Per-Arnst-Sim (PAS) sensor domain. Interestingly, LjPAS is fused to the FMN reductase domains in other lactobacillaceae. In L. johnsonii, LjPAS is encoded by an independent gene which expression is repressed under anaerobic conditions (>3 fold). Purified LjPAS was able to slow down the FRedA/B initial activity rate when the holoenzyme precursors (FredA, FredB, and FMN) were mixed in vitro. Altogether the results obtained suggest that LjPAS module regulates the H2O2 production helping the cells to minimize oxidative stress in response to environmental conditions.

Proteomic and transcriptional analysis of Lactobacillus johnsonii PF01 during bile salt exposure by iTRAQ shotgun proteomics and quantitative RT-PCR.

PubMed

Lee, Ji Yoon; Pajarillo, Edward Alain B; Kim, Min Jeong; Chae, Jong Pyo; Kang, Dae-Kyung

2013-01-04

Lactobacillus johnsonii PF01 has been reported to be highly resistant to bile, a key property of probiotic microorganisms. Here, we examine the nature of the bile-salt tolerance of L. johnsonii PF01. Growth inhibition and surface morphology and physiology aberrations were observed after overnight exposure to bile stress. Quantitative proteomic profiles using iTRAQ-LC-MS/MS technology identified 8307 peptides from both untreated PF01 cells and those exposed to 0.1%, 0.2%, and 0.3% bile salts. Some 215 proteins exhibited changed levels in response to bile stress; of these, levels of 94 peptides increased while those of 121 decreased. These were classified into the following categories: stress responses, cell division, transcription, translation, nucleotide metabolism, carbohydrate transport and metabolism, cell wall biosynthesis, and amino acid biosynthesis, and 16 of unidentified function. Analysis of the mRNA expression of selected genes by quantitative reverse transcriptase-PCR verified the proteomic data. Both proteomic and mRNA data provided evidence for increased phosphotransferase activity and cell wall biosynthesis. In addition, three bile salt hydrolases were significantly upregulated by bile exposure. These findings provide a basis for future evaluations of the tolerance of potential probiotic strains toward the various gastrointestinal challenges, including bile stress.

Genome shuffling improves production of the low-temperature alkalophilic lipase by Acinetobacter johnsonii.

PubMed

Wang, HaiKuan; Zhang, Jie; Wang, XiaoJie; Qi, Wei; Dai, YuJie

2012-01-01

The production of a low-temperature alkalophilic lipase from Acinetobacter johnsonii was improved using genome shuffling. The starting populations, obtained by UV irradiation and diethyl sulfate mutagenesis, were subjected to recursive protoplast fusion. The optimal conditions for protoplast formation and regeneration were 0.15 mg lysozyme/ml for 45 min at 37°C. The protoplasts were inactivated under UV for 20 min or heated at 60°C for 60 min and a fusant probability of ~98% was observed. The positive colonies were created by fusing the inactivated protoplasts. After two rounds of genome shuffling, one strain, F22, with a lipase activity of 7 U/ml was obtained.

Inhibition of Bacillus cereus Strains by Antimicrobial Metabolites from Lactobacillus johnsonii CRL1647 and Enterococcus faecium SM21.

PubMed

Soria, M Cecilia; Audisio, M Carina

2014-12-01

Bacillus cereus is an endospore-forming, Gram-positive bacterium able to cause foodborne diseases. Lactic acid bacteria (LAB) are known for their ability to synthesize organic acids and bacteriocins, but the potential of these compounds against B. cereus has been scarcely documented in food models. The present study has examined the effect of the metabolites produced by Lactobacillus johnsonii CRL1647 and Enterococcus faecium SM21 on the viability of select B. cereus strains. Furthermore, the effect of E. faecium SM21 metabolites against B. cereus strains has also been investigated on a rice food model. L. johnsonii CRL1647 produced 128 mmol/L of lactic acid, 38 mmol/L of acetic acid and 0.3 mmol/L of phenyl-lactic acid. These organic acids reduced the number of vegetative cells and spores of the B. cereus strains tested. However, the antagonistic effect disappeared at pH 6.5. On the other hand, E. faecium SM21 produced only lactic and acetic acid (24.5 and 12.2 mmol/L, respectively) and was able to inhibit both vegetative cells and spores of the B. cereus strains, at a final fermentation pH of 5.0 and at pH 6.5. This would indicate the action of other metabolites, different from organic acids, present in the cell-free supernatant. On cooked rice grains, the E. faecium SM21 bacteriocin(s) were tested against two B. cereus strains. Both of them were significantly affected within the first 4 h of contact; whereas B. cereus BAC1 cells recovered after 24 h, the effect on B. cereus 1 remained up to the end of the assay. The LAB studied may thus be considered to define future strategies for biological control of B. cereus.

The role of prophage for genome diversification within a clonal lineage of Lactobacillus johnsonii: characterization of the defective prophage LJ771.

PubMed

Denou, Emmanuel; Pridmore, Raymond David; Ventura, Marco; Pittet, Anne-Cécile; Zwahlen, Marie-Camille; Berger, Bernard; Barretto, Caroline; Panoff, Jean-Michel; Brüssow, Harald

2008-09-01

Two independent isolates of the gut commensal Lactobacillus johnsonii were sequenced. These isolates belonged to the same clonal lineage and differed mainly by a 40.8-kb prophage, LJ771, belonging to the Sfi11 phage lineage. LJ771 shares close DNA sequence identity with Lactobacillus gasseri prophages. LJ771 coexists as an integrated prophage and excised circular phage DNA, but phage DNA packaged into extracellular phage particles was not detected. Between the phage lysin gene and attR a likely mazE ("antitoxin")/pemK ("toxin") gene cassette was detected in LJ771 but not in the L. gasseri prophages. Expressed pemK could be cloned in Escherichia coli only together with the mazE gene. LJ771 was shown to be highly stable and could be cured only by coexpression of mazE from a plasmid. The prophage was integrated into the methionine sulfoxide reductase gene (msrA) and complemented the 5' end of this gene, creating a protein with a slightly altered N-terminal sequence. The two L. johnsonii strains had identical in vitro growth and in vivo gut persistence phenotypes. Also, in an isogenic background, the presence of the prophage resulted in no growth disadvantage.

EpsA is an essential gene in exopolysaccharide production in Lactobacillus johnsonii FI9785.

PubMed

Dertli, Enes; Mayer, Melinda J; Colquhoun, Ian J; Narbad, Arjan

2016-07-01

Lactobacillus johnsonii FI9785 has an eps gene cluster which is required for the biosynthesis of homopolymeric exopolysaccharides (EPS)-1 and heteropolymeric EPS-2 as a capsular layer. The first gene of the cluster, epsA, is the putative transcriptional regulator. In this study we showed the crucial role of epsA in EPS biosynthesis by demonstrating that deletion of epsA resulted in complete loss of both EPS-1 and EPS-2 on the cell surface. Plasmid complementation of the epsA gene fully restored EPS production, as confirmed by transmission electron microscopy and nuclear magnetic resonance (NMR) analysis. Furthermore, this complementation resulted in a twofold increase in the expression levels of this gene, which almost doubled amounts of EPS production in comparison with the wild-type strain. Analysis of EPS by NMR showed an increased ratio of the heteropolysaccharide to homopolysaccharide in the complemented strain and allowed identification of the acetylated residue in EPS-2 as the (1,4)-linked βGlcp unit, with the acetyl group located at O-6. These findings indicate that epsA is a positive regulator of EPS production and that EPS production can be manipulated by altering its expression. © 2015 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Adaptation to Aerobic Environment of Lactobacillus johnsonii/gasseri Strains

PubMed Central

Maresca, Diamante; Zotta, Teresa; Mauriello, Gianluigi

2018-01-01

Oxygen is considered one of the main factors affecting probiotic bacteria survival due to the induction of oxidative damages caused by the action of reactive oxygen species (ROS). It has been shown that oxidative stress resistance in lactic acid bacteria is strongly dependent on the type of cell metabolism. Shift from fermentative to respiratory metabolism (through the addition of heme and menaquinone and in presence of oxygen) was associated to increase in biomass, long-term survival, and production of antioxidant enzymes. The aim of this work was to investigate the effect of aerobic (presence of oxygen) and respiratory (presence of oxygen, heme, and menaquinone) cultivation on the growth kinetic, catalase production, oxygen uptake, and oxidative stress response of Lactobacillus johnsonii/gasseri strains previously isolated from infant feces. Seven strains showed to consume oxygen under aerobic and respiratory conditions. The strain AL5 showed a catalase activity in both growth conditions, while AL3 showed this activity only in respiratory condition. Respiratory condition improved their tolerance to oxidative compounds (hydrogen peroxide and ROS generators) and further they showed promising probiotic features. The exploration of respiratory competent phenotypes with probiotic features may be extremely useful for the development of competitive starter or probiotic cultures. PMID:29479342

Adaptation to Aerobic Environment of Lactobacillus johnsonii/gasseri Strains.

PubMed

Maresca, Diamante; Zotta, Teresa; Mauriello, Gianluigi

2018-01-01

Oxygen is considered one of the main factors affecting probiotic bacteria survival due to the induction of oxidative damages caused by the action of reactive oxygen species (ROS). It has been shown that oxidative stress resistance in lactic acid bacteria is strongly dependent on the type of cell metabolism. Shift from fermentative to respiratory metabolism (through the addition of heme and menaquinone and in presence of oxygen) was associated to increase in biomass, long-term survival, and production of antioxidant enzymes. The aim of this work was to investigate the effect of aerobic (presence of oxygen) and respiratory (presence of oxygen, heme, and menaquinone) cultivation on the growth kinetic, catalase production, oxygen uptake, and oxidative stress response of Lactobacillus johnsonii/gasseri strains previously isolated from infant feces. Seven strains showed to consume oxygen under aerobic and respiratory conditions. The strain AL5 showed a catalase activity in both growth conditions, while AL3 showed this activity only in respiratory condition. Respiratory condition improved their tolerance to oxidative compounds (hydrogen peroxide and ROS generators) and further they showed promising probiotic features. The exploration of respiratory competent phenotypes with probiotic features may be extremely useful for the development of competitive starter or probiotic cultures.

Gene expression of commensal Lactobacillus johnsonii strain NCC533 during in vitro growth and in the murine gut.

PubMed

Denou, Emmanuel; Berger, Bernard; Barretto, Caroline; Panoff, Jean-Michel; Arigoni, Fabrizio; Brüssow, Harald

2007-11-01

Work with pathogens like Vibrio cholerae has shown major differences between genes expressed in bacteria grown in vitro and in vivo. To explore this subject for commensals, we investigated the transcription of the Lactobacillus johnsonii NCC533 genome during in vitro and in vivo growth using the microarray technology. During broth growth, 537, 626, and 277 of the 1,756 tested genes were expressed during exponential phase, "adaptation" (early stationary phase), and stationary phase, respectively. One hundred one, 150, and 33 genes, respectively, were specifically transcribed in these three phases. To explore the in vivo transcription program, we fed L. johnsonii containing a resistance plasmid to antibiotic-treated mice. After a 2-day washout phase, we determined the viable-cell counts of lactobacilli that were in the lumina and associated with the mucosae of different gut segments. While the cell counts showed a rather uniform distribution along the gut, we observed marked differences with respect to the expression of the Lactobacillus genome. The largest number of transcribed genes was in the stomach (n = 786); the next-largest numbers occurred in the cecum (n = 391) and the jejunum (n = 296), while only 26 Lactobacillus genes were transcribed in the colon. In vitro and in vivo transcription programs overlapped only partially. One hundred ninety-one of the transcripts from the lactobacilli in the stomach were not detected during in vitro growth; 202 and 213 genes, respectively, were transcribed under all in vitro and in vivo conditions; but the core transcriptome for all growth conditions comprised only 103 genes. Forty-four percent of the NCC533 genes were not detectably transcribed under any of the investigated conditions. Nontranscribed genes were clustered on the genome and enriched in the variable-genome part. Our data revealed not only major differences between in vitro- and in vivo-expressed genes in a Lactobacillus gut commensal organism but also marked

Lactobacillus johnsonii CRL1647, isolated from Apis mellifera L. bee-gut, exhibited a beneficial effect on honeybee colonies.

PubMed

Audisio, M C; Benítez-Ahrendts, M R

2011-03-01

Lactobacillus johnsonii CRL1647, isolated from the intestinal tract of a honeybee and selected due to its high lactic acid production, was assayed as a monoculture on bee colony performance. It was delivered to the bees on a one litre of 125 g/l sugar-cane syrup with a final concentration of 105 cfu/ml lactobacilli. The bees accepted the new nourishment, which was consumed within 24-48 h and was administered in two independent trials (every 14-15 days for 3 consecutive months in one case, and once a month for 13 consecutive months in the other). From late spring - early summer (2008) the photo-records and statistical analyses revealed significant differences in the open and the operculated brood areas in the treated group compared with the control. This stimulation was observed after the first administration of the lactobacilli and maintained throughout. Also, a higher number of bees were measured in the treated group (54%) and the control (18%) with respect to the initial bees' number. Furthermore, honey storage was higher, 40% and 19%, for the treated and control groups, respectively. From December 2008 to December 2009, a similar situation was observed even though, in this trial, the lactobacilli cells were administered once a month. The in vivo results of this study are promising and indicate that a L. johnsonii CRL1647 supplement to beehives favours mainly open and operculated brood areas, demonstrating a stronger stimulation of egg-laying and will become a natural product which will assist the beekeeper both in colony management and the creation of late nuclei and/or bee packages due to its beneficial effects in the beehive colony.

Molecular cloning, characterization and comparison of bile salt hydrolases from Lactobacillus johnsonii PF01.

PubMed

Chae, J P; Valeriano, V D; Kim, G-B; Kang, D-K

2013-01-01

To clone, characterize and compare the bile salt hydrolase (BSH) genes of Lactobacillus johnsonii PF01. The BSH genes were amplified by polymerase chain reaction (PCR) using specific oligonucleotide primers, and the products were inserted into the pET21b expression vector. Escherichia coli BLR (DE3) cells were transformed with pET21b vectors containing the BSH genes and induced using 0·1 mmol l(-1) isopropylthiolgalactopyranoside. The overexpressed BSH enzymes were purified using a nickel-nitrilotriacetic acid (Ni(2+) -NTA) agarose column and their activities characterized. BSH A hydrolysed tauro-conjugated bile salts optimally at pH 5·0 and 55°C, whereas BSH C hydrolysed glyco-conjugated bile salts optimally at pH 5·0 and 70°C. The enzymes had no preferential activities towards a specific cholyl moiety. BSH enzymes vary in their substrate specificities and characteristics to broaden its activity. Despite the lack of conservation in their putative substrate-binding sites, these remain functional through motif conservation. This is to our knowledge the first report of isolation of BSH enzymes from a single strain, showing hydrolase activity towards either glyco-conjugated or tauro-conjugated bile salts. Future structural homology studies and site-directed mutagenesis of sites associated with substrate specificity may elucidate specificities of BSH enzymes. © 2012 The Society for Applied Microbiology.

Excretion into feces of asialo GM1 in the murine digestive tract and Lactobacillus johnsonii exhibiting binding ability toward asialo GM1. A possible role of epithelial glycolipids in the discharge of intestinal bacteria.

PubMed

Iwamori, Masao; Iwamori, Yuriko; Adachi, Shigeki; Nomura, Taisei

2011-01-01

In the digestive tract of mice (HR-1, 5 months old, ♀), asialo GM1 (GA1) exhibiting receptor activity toward several intestinal bacteria was preferentially expressed in the small intestine. Also, less than 10% of GA1 in the small intestine was converted into fucosylated and sulfated derivatives, but it was completely converted to fucosyl GA1 (FGA1) in the stomach, cecum and colon. Among the lipid components in these tissues, glycolipids other than Forssman antigen and cholesterol sulfate (CS) were present in the digestive tract contents. However, sulfated GA1, sulfatide and fucosyl GM1 in the gastro-intestinal contents were not present in the cecal and colonic contents, in which the major glycolipids were ceramide monohexoside (CMH), GA1 and FGA1. The total amount of GA1 in the whole contents was 20% of that in the tissues. Thus, glycolipids were stable during the process of digestion, and excreted from the body together with cholesterol and CS. On the other hand, Lactobacillus johnsonii (LJ), whose receptor is GA1, was detected in the cecal and colonic contents on sequential analysis of 16S-ribosomal RNA and TLC-immunostaining of antigenic glycolipids with anti-LJ antiserum. LJ was found to comprise 20% of the total bacteria cultured in the lactobacillus medium under aerobic conditions, and to be present in the cecal and colonic contents, 9.8 × 10(7) cells versus 37 μg GA1 and 1.4 × 10(8) cells versus 49 μg GA1, respectively. Thus, GA1 in the contents might facilitate the discharge of intestinal bacteria by becoming attached them to prevent their irregular diffusion.

Growth of probiotic bacteria and bifidobacteria in a soy yogurt formulation.

PubMed

Farnworth, E R; Mainville, I; Desjardins, M-P; Gardner, N; Fliss, I; Champagne, C

2007-05-01

Soy beverage and cows' milk yogurts were produced with Steptococcus thermophilus (ATCC 4356) and Lactobacillus delbrueckii subsp. bulgaricus (IM 025). The drop in pH during fermentation was faster in the soy beverage than in cows' milk, but the final pH values were similar. Yogurts were prepared with a yogurt starter in conjunction with either the probiotic bacteria Lactobacillus johnsonii NCC533 (La-1), Lactobacillus rhamnosus ATCC 53103 (GG) or human derived bifidobacteria. The presence of the probiotic bacteria did not affect the growth of the yogurt strains. Approximately 2 log increases in both L. rhamnosus GG and L. johnsonii La-1 were observed when each was added with the yogurt strains in both cows' milk and the soy beverage. Two of the five bifidobacteria strains grew well in the cows' milk and soy beverage during fermentation with the yogurt bacteria. High pressure liquid chromatography (HPLC) analyses showed that the probiotic bacteria and the bifidobacteria were using different sugars to support their growth, depending on whether the bacteria were growing in cows' milk or soy beverage.

Differential Effect of Lactobacillus johnsonii BFE 6128 on Expression of Genes Related to TLR Pathways and Innate Immunity in Intestinal Epithelial Cells.

PubMed

Seifert, Stephanie; Rodriguez Gómez, Manuel; Watzl, Bernhard; Holzapfel, Wilhelm H; Franz, Charles M A P; Vizoso Pinto, María G

2010-12-01

Probiotics have been shown to enhance immune defenses, but their mechanisms of action are only partially understood. We investigated the modulation of signal pathways involved in innate immunity in enterocytes by Lactobacillus johnsonii BFE 6128 isolated from 'Kule naoto', a Maasai traditional fermented milk product. This lactobacillus sensitized HT29 intestinal epithelial cells toward recognition of Salmonella enterica serovar Typhimurium by increasing the IL-8 levels released after challenge with this pathogen and by differentially modulating genes related to toll-like receptor (TLR) pathways and innate immunity. Thus, the modulation of pro-inflammatory mediators and TLR-pathway-related molecules may be an important mechanism contributing to the potential stimulation of innate immunity by lactobacilli at the intestinal epithelial level.

An Inserted α/β Subdomain Shapes the Catalytic Pocket of Lactobacillus johnsonii Cinnamoyl Esterase

PubMed Central

Vu, Clara; Xu, Xiaohui; Cui, Hong; Molloy, Sara; Savchenko, Alexei; Yakunin, Alexander; Gonzalez, Claudio F.

2011-01-01

Background Microbial enzymes produced in the gastrointestinal tract are primarily responsible for the release and biochemical transformation of absorbable bioactive monophenols. In the present work we described the crystal structure of LJ0536, a serine cinnamoyl esterase produced by the probiotic bacterium Lactobacillus johnsonii N6.2. Methodology/Principal Findings We crystallized LJ0536 in the apo form and in three substrate-bound complexes. The structure showed a canonical α/β fold characteristic of esterases, and the enzyme is dimeric. Two classical serine esterase motifs (GlyXSerXGly) can be recognized from the amino acid sequence, and the structure revealed that the catalytic triad of the enzyme is formed by Ser106, His225, and Asp197, while the other motif is non-functional. In all substrate-bound complexes, the aromatic acyl group of the ester compound was bound in the deepest part of the catalytic pocket. The binding pocket also contained an unoccupied area that could accommodate larger ligands. The structure revealed a prominent inserted α/β subdomain of 54 amino acids, from which multiple contacts to the aromatic acyl groups of the substrates are made. Inserts of this size are seen in other esterases, but the secondary structure topology of this subdomain of LJ0536 is unique to this enzyme and its closest homolog (Est1E) in the Protein Databank. Conclusions The binding mechanism characterized (involving the inserted α/β subdomain) clearly differentiates LJ0536 from enzymes with similar activity of a fungal origin. The structural features herein described together with the activity profile of LJ0536 suggest that this enzyme should be clustered in a new group of bacterial cinnamoyl esterases. PMID:21876742

An inserted α/β subdomain shapes the catalytic pocket of Lactobacillus johnsonii cinnamoyl esterase.

PubMed

Lai, Kin-Kwan; Stogios, Peter J; Vu, Clara; Xu, Xiaohui; Cui, Hong; Molloy, Sara; Savchenko, Alexei; Yakunin, Alexander; Gonzalez, Claudio F

2011-01-01

Microbial enzymes produced in the gastrointestinal tract are primarily responsible for the release and biochemical transformation of absorbable bioactive monophenols. In the present work we described the crystal structure of LJ0536, a serine cinnamoyl esterase produced by the probiotic bacterium Lactobacillus johnsonii N6.2. We crystallized LJ0536 in the apo form and in three substrate-bound complexes. The structure showed a canonical α/β fold characteristic of esterases, and the enzyme is dimeric. Two classical serine esterase motifs (GlyXSerXGly) can be recognized from the amino acid sequence, and the structure revealed that the catalytic triad of the enzyme is formed by Ser(106), His(225), and Asp(197), while the other motif is non-functional. In all substrate-bound complexes, the aromatic acyl group of the ester compound was bound in the deepest part of the catalytic pocket. The binding pocket also contained an unoccupied area that could accommodate larger ligands. The structure revealed a prominent inserted α/β subdomain of 54 amino acids, from which multiple contacts to the aromatic acyl groups of the substrates are made. Inserts of this size are seen in other esterases, but the secondary structure topology of this subdomain of LJ0536 is unique to this enzyme and its closest homolog (Est1E) in the Protein Databank. The binding mechanism characterized (involving the inserted α/β subdomain) clearly differentiates LJ0536 from enzymes with similar activity of a fungal origin. The structural features herein described together with the activity profile of LJ0536 suggest that this enzyme should be clustered in a new group of bacterial cinnamoyl esterases.

Identification of Genes Encoding Conjugated Bile Salt Hydrolase and Transport in Lactobacillus johnsonii 100-100

PubMed Central

Elkins, Christopher A.; Savage, Dwayne C.

1998-01-01

Cytosolic extracts of Lactobacillus johnsonii 100-100 (previously reported as Lactobacillus sp. strain 100-100) contain four heterotrimeric isozymes composed of two peptides, α and β, with conjugated bile salt hydrolase (BSH) activity. We now report cloning, from the genome of strain 100-100, a 2,977-bp DNA segment that expresses BSH activity in Escherichia coli. The sequencing of this segment showed that it contained one complete and two partial open reading frames (ORFs). The 3′ partial ORF (927 nucleotides) was predicted by BLAST and confirmed with 5′ and 3′ deletions to be a BSH gene. Thermal asymmetric interlaced PCR was used to extend and complete the 948-nucleotide sequence of the BSH gene 3′ of the cloned segment. The predicted amino acid sequence of the 5′ partial ORF (651 nucleotides) was about 80% similar to the C-terminal half of the largest, complete ORF (1,353 nucleotides), and these two putative proteins were similar to several amine, multidrug resistance, and sugar transport proteins of the major facilitator superfamily. E. coli DH5α cells transformed with a construct containing these ORFs, in concert with an extracellular factor produced by strain 100-100, demonstrated levels of uptake of [14C]taurocholic acid that were increased as much as threefold over control levels. [14C]Cholic acid was taken up in similar amounts by strain DH5α pSportI (control) and DH5α p2000 (transport clones). These findings support a hypothesis that the ORFs are conjugated bile salt transport genes which may be arranged in an operon with BSH genes. PMID:9721268

Heat-Killed Lactobacillus salivarius and Lactobacillus johnsonii Reduce Liver Injury Induced by Alcohol In Vitro and In Vivo.

PubMed

Chuang, Cheng-Hung; Tsai, Cheng-Chih; Lin, En-Shyh; Huang, Chin-Shiu; Lin, Yun-Yu; Lan, Chuan-Ching; Huang, Chun-Chih

2016-10-31

The aim of the present study was to determine whether Lactobacillus salivarius (LS) and Lactobacillus johnsonii (LJ) prevent alcoholic liver damage in HepG2 cells and rat models of acute alcohol exposure. In this study, heat-killed LS and LJ were screened from 50 Lactobacillus strains induced by 100 mM alcohol in HepG2 cells. The severity of alcoholic liver injury was determined by measuring the levels of aspartate transaminase (AST), alanine transaminase (ALT), gamma-glutamyl transferase (γ-GT), lipid peroxidation, triglyceride (TG) and total cholesterol. Our results indicated that heat-killed LS and LJ reduced AST, ALT, γ-GT and malondialdehyde (MDA) levels and outperformed other bacterial strains in cell line studies. We further evaluated these findings by administering these strains to rats. Only LS was able to reduce serum AST levels, which it did by 26.2%. In addition LS significantly inhibited serum TG levels by 39.2%. However, both strains were unable to inhibit ALT levels. In summary, we demonstrated that heat-killed LS and LJ possess hepatoprotective properties induced by alcohol both in vitro and in vivo.

A trial of adding Lactobacillus johnsonii EM1 to levocetirizine for treatment of perennial allergic rhinitis in children aged 7-12 years.

PubMed

Lue, Ko-Haung; Sun, Hai-Lun; Lu, Ko-Hsiu; Ku, Min-Sho; Sheu, Ji-Nan; Chan, Ching-Hui; Wang, Yun-Hu

2012-07-01

Supplementary consumption of probiotics may temporarily alter the intestinal microflora of infants and children, thereby preventing and treating allergic disorders. To compare the clinical efficacy of levocetirizine with that of levocetirizine plus Lactobacillus johnsonii EM1 (Lj EM1) for treating perennial allergic rhinitis (PAR) in children. Sixty-three children aged 7-12 years fulfilled the entry criteria for the study and had moderate to severe PAR of at least 1 year's duration. The treatment followed a randomized, open-label crossover design: all subjects were randomized to 2 crossover treatment regimens of levocetirizine with Lj EM1 (group 1) or levocetirizine alone (group 2) for 12 weeks; subsequently, treatments were reversed for a further 12 weeks. The effects of the 2 regimens were compared using the Pediatric Rhinoconjunctivitis Quality of Life Questionnaire (PRQLQ) and the total symptom score (TSS) from diary cards. The parameters evaluated were nasal peak expiratory flow rate (nPEFR), FVC, FEV1, serum immunoglobulin E (IgE), mite-specific IgE, eosinophilic cationic protein (ECP), resistin, blood eosinophils, eosinophil percentage in nasal smears, IL-4, IL-10, interferon-γ (IFN-γ), and transforming growth factor-β (TGF-β). After the first 12 weeks of treatment, TSS in both groups had improved progressively compared with that in the run-in period. Both groups had improved TSS at weeks 4, 8, and 12 (P<0.05), and group 1 was more efficacious than group 2 at week 4 (P=0.014), week 8 (P=0.011), and week 12 (P<0.009). During the second 12-week period, group 2 showed continual and progressive improvement, while group 1 did not. The PRQLQ scores were significantly decreased in both groups (P<0.05), but there was no statistically significant difference between the 2 groups (P=0.446). The eosinophil percentage in nasal smears decreased in both groups compared with that in the run-in period, and significant differences were detected in groups 2 and 1at 16 and

Analysis of hepatic transcriptome demonstrates altered lipid metabolism following Lactobacillus johnsonii BS15 prevention in chickens with subclinical necrotic enteritis.

PubMed

Qing, Xiaodan; Zeng, Dong; Wang, Hesong; Ni, Xueqin; Lai, Jing; Liu, Lei; Khalique, Abdul; Pan, Kangcheng; Jing, Bo

2018-04-20

Subclinical necrotic enteritis (SNE) widely outbreaks in chickens which inflicted growth-slowing, causing enormous social and economic burdens. To better understand the molecular underpinnings of SNE on lipid metabolism and explore novel preventative strategies against SNE, we studied the regulatory mechanism of a potential probiotic, Lactobacillus johnsonii BS15 on the lipid metabolism pathways involved in chickens with SNE. One hundred eighty one-day-old chickens were randomly divided into three groups and arranged with basal diet (control and SNE group). Added with BS15 (1 × 10 6  cfu/g) or Man Rogosa Sharpe (MRS) liquid medium for 28 days. The hepatic gene expression of each group was then measured using high-throughput analysis methods (RNA-Seq). Quantitative real-time PCR (qRT-PCR) was used to detect the expression changes of the related genes. The results showed that there are eleven lipid metabolic pathways were found during the prevention of BS15 treatment in SNE chickens by RNA-Seq, including the peroxisome proliferator-activated receptor (PPAR) signaling pathway and arachidonic acid metabolism. BS15 notably facilitated the expressions of fatty acid binding protein 2 (FABP2), acyl-CoA synthetase bubblegum family member 1 (ACSBG1), perilipin 1 (PLIN1) and perilipin 2 (PLIN2), which were involved in PPAR signaling pathway of SNE chickens. Besides, suppression of phospholipase A2 group IVA (PLA2G4A) in arachidonic acid metabolism was observed in SNE chickens after BS15 prevention. The expression patterns of FABP2, ACSBG1, PLIN1, PLIN2 and PLA24G in qRT-PCR validation were consistent with RNA-Seq results. These findings indicate that SNE may affect the hepatic lipid metabolism of chickens. Meanwhile, BS15 pretreatment may provide a prospective natural prophylaxis strategy against SNE through improving the PPAR signaling pathway and arachidonic acid metabolism.

PubMed

López Gómez, Juan José; Pérez Castrillón, José Luis; Romero Bobillo, Enrique; De Luis Román, Daniel A

2016-11-29

La obesidad interfiere con el metabolismo óseo a través de factores mecánicos, hormonales e inflamatorios. El principal tratamiento de dicha enfermedad es la dieta, modificación de la cantidad y tipo de alimento. Este tratamiento nutricional tiene una influencia sobre el metabolismo óseo en dos sentidos: modifica el efecto del sobrepeso y la obesidad sobre el hueso e interviene directamente en el turnoveróseo a través de las características de los nutrientes utilizados. Esta revisión analiza la evidencia del efecto sobre el hueso del descenso de peso y del patrón dietético utilizado. Por otra parte, se valorarán las modificaciones que se pueden realizar en la dieta indicada en un paciente obeso para prevenir la pérdida ósea, a corto y largo plazo, y disminuir el riesgo de fractura.

Controlling of growth performance, lipid deposits and fatty acid composition of chicken meat through a probiotic, Lactobacillus johnsonii during subclinical Clostridium perfringens infection.

PubMed

Wang, Hesong; Ni, Xueqin; Liu, Lei; Zeng, Dong; Lai, Jing; Qing, Xiaodan; Li, Guangyao; Pan, Kangcheng; Jing, Bo

2017-02-10

Meat is considered as a major source of polyunsaturated fatty acid (PUFA) which is essential for humans, therefore its lipid level and fatty acid composition have drawn great attention. As no clinical sign can be found in chicks subclinically infected by Clostridium perfringens (CP), the meat may be purchased and eaten. The objective of the present study was to determine whether Lactobacillus johnsonii (LJ) can control the CP-caused impact on growth, lipid levels, fatty acid composition and other flavor or nutritional quality in the meat. 480 one-day-old chicks were divided into four groups and fed with basal diet (control and CP group). Supplemented with 1 × 10 5 (L-LJ) and 1 × 10 6 (H-LJ) colony-forming unit (cfu), CP diet was fed for 42 days. From day 19 to 22, birds of CP and LJ groups were administered with CP twice per day and the control was administered with liver broth. LJ-treated chickens were free from negative influences on growth performance and significant decrease of abdominal fat deposit., LJ inhibited CP-caused shearing force and drip loss increase and pH 40 min and 24 h decrease after sacrifice. In addition, LJ exhibited a positive effect on muscle lipid peroxidation by significantly increasing SOD, CAT and GSH-Px activity and decreasing MDA level. Besides, LJ attenuated the decrease of intramuscular fat, total cholesterol and triglyceride contents caused by CP infection. However, levels of total protein and most of amino acids were not changed. CP infection decreased C18:3n-3 (α-LA), C20:4n-6, C20:5n-3(EPA), C22:4n-6, C22:5n-3, C22:6n-3(DHA), total PUFA, n-3 PUFA and PUFA:SFA ratio and increased C14:0, total SFA and n-6:n-3 ratio. LJ was found to protect the muscle from these changes. Meanwhile, the 28-day gut permeability level was higher in CP group. These findings suggest that CP may affect the growth performance of chicks and negatively influence lipid content and fatty acid composition in chicken meat. Meanwhile, LJ treatment

Evolution of Fermi Surface Properties in CexLa1-xB6 and PrxLa1-xB6

NASA Astrophysics Data System (ADS)

Endo, Motoki; Nakamura, Shintaro; Isshiki, Toshiyuki; Kimura, Noriaki; Nojima, Tsutomu; Aoki, Haruyoshi; Harima, Hisatomo; Kunii, Satoru

2006-11-01

We report the de Haas-van Alphen (dHvA) effect measurements of the Fermi surface properties in LaB6, CexLa1-xB6 (x = 0.1, 0.25, 0.5, 0.75, 1.0) and PrxLa1-xB6 (x = 0.25, 0.5, 0.75, 1.0) with particular attention to the spin dependence of the Fermi surface properties. The Fermi surface shape and dimension of CexLa1-xB6 change considerably with Ce concentration, while those of PrxLa1-xB6 change very slightly up to x = 0.75, and in PrB6 the Fermi surface splits into the up and down spin Fermi surfaces. The effective mass of CexLa1-xB6 increases considerably with Ce concentration and is nearly proportional to the number of Ce ions, whereas that of PrxLa1-xB6 increases slightly with Pr concentration. In CexLa1-xB6 the effective mass depends very strongly on field and increases divergently with decreasing field, while that of PrxLa1-xB6 increases slightly with decreasing field. The contribution to the dHvA signal from the conduction electrons of one spin direction diminishes with Ce concentration and appears to disappear somewhere around x = 0.25--0.5. A weak spin dependence is also found in PrxLa1-xB6. The behaviors of CexLa1-xB6 and PrxLa1-xB6 are compared to discuss the origin of the spin dependence of the Fermi surface properties.

Probiotic Lactobacillus johnsonii BS15 Improves Blood Parameters Related to Immunity in Broilers Experimentally Infected with Subclinical Necrotic Enteritis

PubMed Central

Wang, Hesong; Ni, Xueqin; Qing, Xiaodan; Liu, Lei; Xin, Jinge; Luo, Min; Khalique, Abdul; Dan, Yan; Pan, Kangcheng; Jing, Bo; Zeng, Dong

2018-01-01

The probiotic strain Lactobacillus johnsonii BS15 could exert beneficial effects on growth performance, lipid metabolism, and intestinal microflora in healthy broilers and those afflicted with subclinical necrotic enteritis (SNE). In particular, BS15 prevents SNE by enhancing intestinal immunity. To further understand the immune regulatory mechanism of BS15, we evaluated its effects on the overall immunity of broilers by determining blood parameters in healthy and SNE broilers. In this study, two experiments were conducted. Experiment 1 involved a 42-day experimental period and used 450 1-day-old male chicks. The chicks were randomly divided into three groups and fed with a basal diet with or without 1 × 105 or 106 colony-forming units (cfu) BS15/g as feed. Experiment 2 involved a 28-day experimental period and used 180 1-day-old male chicks. The chicks were randomly allotted into three groups and given with or without 1 × 106 cfu BS15/g BS15 as feed. SNE infection was treated in all broilers, except in those in the normal diet group. Antioxidant abilities, immunoglobulins, and cytokines in the serum were assessed. T-lymphocyte subsets in peripheral blood were also determined. The first experiment demonstrated that BS15 enhanced the antioxidant abilities; the serum levels of immunoglobulins, interleukin-2, and interferon-gamma; and CD3+CD4+ T-lymphocyte percentage in peripheral blood on day 21. However, limited significant changes were observed on day 42. The second experiment revealed that BS15 supplementation positively influenced the antioxidant abilities and increased the serum levels of immunoglobulins and cytokines that were affected by SNE. BS15 also positively affected T-lymphocyte subsets in peripheral blood during SNE infection. These findings suggest that BS15 supplementation may prevent SNE in broilers by improving blood parameters related to immunity and enhancing intestinal immunity. Furthermore, BS15 supplementation can improve blood parameters in

Probiotic Lactobacillus johnsonii BS15 Improves Blood Parameters Related to Immunity in Broilers Experimentally Infected with Subclinical Necrotic Enteritis.

PubMed

Wang, Hesong; Ni, Xueqin; Qing, Xiaodan; Liu, Lei; Xin, Jinge; Luo, Min; Khalique, Abdul; Dan, Yan; Pan, Kangcheng; Jing, Bo; Zeng, Dong

2018-01-01

The probiotic strain Lactobacillus johnsonii BS15 could exert beneficial effects on growth performance, lipid metabolism, and intestinal microflora in healthy broilers and those afflicted with subclinical necrotic enteritis (SNE). In particular, BS15 prevents SNE by enhancing intestinal immunity. To further understand the immune regulatory mechanism of BS15, we evaluated its effects on the overall immunity of broilers by determining blood parameters in healthy and SNE broilers. In this study, two experiments were conducted. Experiment 1 involved a 42-day experimental period and used 450 1-day-old male chicks. The chicks were randomly divided into three groups and fed with a basal diet with or without 1 × 10 5 or 10 6 colony-forming units (cfu) BS15/g as feed. Experiment 2 involved a 28-day experimental period and used 180 1-day-old male chicks. The chicks were randomly allotted into three groups and given with or without 1 × 10 6 cfu BS15/g BS15 as feed. SNE infection was treated in all broilers, except in those in the normal diet group. Antioxidant abilities, immunoglobulins, and cytokines in the serum were assessed. T-lymphocyte subsets in peripheral blood were also determined. The first experiment demonstrated that BS15 enhanced the antioxidant abilities; the serum levels of immunoglobulins, interleukin-2, and interferon-gamma; and CD3 + CD4 + T-lymphocyte percentage in peripheral blood on day 21. However, limited significant changes were observed on day 42. The second experiment revealed that BS15 supplementation positively influenced the antioxidant abilities and increased the serum levels of immunoglobulins and cytokines that were affected by SNE. BS15 also positively affected T-lymphocyte subsets in peripheral blood during SNE infection. These findings suggest that BS15 supplementation may prevent SNE in broilers by improving blood parameters related to immunity and enhancing intestinal immunity. Furthermore, BS15 supplementation can improve blood

Anti-Helicobacter pylori activity of non-living, heat-killed form of lactobacilli including Lactobacillus johnsonii No.1088.

PubMed

Aiba, Yuji; Ishikawa, Hiroki; Tokunaga, Masayoshi; Komatsu, Yasuhiko

2017-06-15

Some strains of lactic acid bacteria are reported to inhibit the growth of Helicobacter pylori and proposed to be useful to support so-called triple therapy for H. pylori. Although most strains must be alive to exert their anti-H. pylori activity, some lactobacilli strains are effective even when dead. One possible underlying mechanism of such an activity of non-living lactobacilli is reportedly co-aggregation with H. pylori. In this study, we found that a non-living heat-killed form of Lactobacillus johnsonii No.1088 (HK-LJ88) and also that of some other lactobacilli inhibited the growth of H. pylori in vitro. Furthermore, the number of H. pylori in the infected stomach of germ-free mice was significantly decreased by the repeated oral administration of HK-LJ88. Observation by scanning electron microscopy revealed that no co-aggregation had occurred between H. pylori and HK-LJ88; instead, deformations of H. pylori (e.g. disappearance of spiral, bending of cell body, coccoid formation, degradations, etc.) appeared after incubation for 24 h with HK-LJ88. These results suggest that HK-LJ88 inhibited H. pylori activity probably not by co-aggregation but by some unknown mechanism involving HK-LJ88's cell surface molecules and that even non-living lactobacilli are possibly useful to support H. pylori eradication therapy. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Thermoelectric Properties of LaFePO1-xFx and LaFeAsO1-xFx ---Possibility of the Hidden Mass Enhancement of LaFeAsO1-xFx---

NASA Astrophysics Data System (ADS)

Okuda, Tetsuji; Hirata, Wataru; Takemori, Akira; Suzuki, Shinnosuke; Saijo, Satoshi; Miyasaka, Shigeki; Tajima, Setsuko

2011-04-01

We investigated thermoelectric properties for polycrystalline oxypnictide LaFePO1-xFx and LaFeAsO1-xFx. The temperature (T) and F-doping dependences of resistivity (ρ) and Seebeck coefficient (S) are quite different between these compounds. In contrast to a monotonic T dependence and an absence of large F-doping dependences of ρ and S for LaFePO1-xFx, the S for LaFeAsO1-xFx for 0LaFeAsO0.89F0.11. The non-monotonic behavior of S with the relatively large absolute value and the reported T dependence of Hall coefficient for LaFeAsO1-xFx seem to evidence an instability of an orbital order accompanying a stripe-type AF order even in the over F-doping region for LaFeAsO1-xFx and indicate a possibility of a hidden mass enhancement of LaFeAsO1-xFx.

Individual and co-operative roles of lactic acid and hydrogen peroxide in the killing activity of enteric strain Lactobacillus johnsonii NCC933 and vaginal strain Lactobacillus gasseri KS120.1 against enteric, uropathogenic and vaginosis-associated pathogens.

PubMed

Atassi, Fabrice; Servin, Alain L

2010-03-01

The mechanism underlying the killing activity of Lactobacillus strains against bacterial pathogens appears to be multifactorial. Here, we investigate the respective contributions of hydrogen peroxide and lactic acid in killing bacterial pathogens associated with the human vagina, urinary tract or intestine by two hydrogen peroxide-producing strains. In co-culture, the human intestinal strain Lactobacillus johnsonii NCC933 and human vaginal strain Lactobacillus gasseri KS120.1 strains killed enteric Salmonella enterica serovar Typhimurium SL1344, vaginal Gardnerella vaginalis DSM 4944 and urinary tract Escherichia coli CFT073 pathogens. The cell-free culture supernatants (CFCSs) produced the same reduction in SL1344, DSM 4944 and CFT073 viability, whereas isolated bacteria had no effect. The killing activity of CFCSs was heat-stable. In the presence of Dulbecco's modified Eagle's minimum essential medium inhibiting the lactic acid-dependent killing activity, CFCSs were less effective at killing of the pathogens. Catalase-treated CFCSs displayed a strong decreased activity. Tested alone, hydrogen peroxide triggered a concentration-dependent killing activity against all three pathogens. Lactic acid alone developed a killing activity only at concentrations higher than that present in CFCSs. In the presence of lactic acid at a concentration present in Lactobacillus CFCSs, hydrogen peroxide displayed enhanced killing activity. Collectively, these results demonstrate that for hydrogen peroxide-producing Lactobacillus strains, the main metabolites of Lactobacillus, lactic acid and hydrogen peroxide, act co-operatively to kill enteric, vaginosis-associated and uropathogenic pathogens.

Prevention of polymorphic light eruption by oral administration of a nutritional supplement containing lycopene, β-carotene, and Lactobacillus johnsonii: results from a randomized, placebo-controlled, double-blinded study.

PubMed

Marini, Alessandra; Jaenicke, Thomas; Grether-Beck, Susanne; Le Floc'h, Caroline; Cheniti, Ahsène; Piccardi, Nathalie; Krutmann, Jean

2014-08-01

Polymorphic light eruption (PLE) is the most common photodermatosis. Little is known about the efficacy of systemic photoprotection provided by nutritional supplements in PLE patients. The purpose of this study was to assess efficacy of nutritional supplement containing lycopene, β-carotene, and Lactobacillus johnsonii to diminish skin lesions induced by 'photoprovocation' testing in PLE patients. In this randomized, placebo-controlled, double-blinded study, 60 PLE patients were supplemented with the nutritional supplement or placebo. For inducing skin lesions, patient skin was exposed to single daily doses of 100 J/cm2 ultraviolet A1 (UVA1) for two consecutive days. Skin lesions were evaluated using a PLE score. Skin biopsies were taken before and after supplementation from unexposed and exposed skin, and intercellular adhesion molecule 1 (ICAM-1) mRNA expression was assessed by real-time polymerase chain reaction. Prior to supplementation, skin lesions were induced in all patients with comparable PLE scores. After 12 weeks, intake of the supplement significantly reduced the PLE score after one exposure as compared with patients taking placebo (P<0.001). After two exposures, these differences were no longer significant. At a molecular level, the development of skin lesions was associated with an increased expression of ICAM-1 mRNA, which was significantly reduced after supplementation (P=0.022), but not with placebo. The nutritional supplement provides protection against the development of UVA-induced PLE lesions at clinical and molecular levels. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Biochemical Properties of Two Cinnamoyl Esterases Purified from a Lactobacillus johnsonii Strain Isolated from Stool Samples of Diabetes-Resistant Rats▿

PubMed Central

Lai, Kin Kwan; Lorca, Graciela L.; Gonzalez, Claudio F.

2009-01-01

Cinnamic acids (i.e., ferulic and caffeic acids) that are esterified to the vegetable cell walls should be enzymatically released to be absorbed in a mammal's intestines. A low dosage of ferulic acid in rodent diets stimulates insulin production and alleviates symptoms caused by diabetes (M. Sri Balasubashini, R. Rukkumani, and V. P. Menon, Acta Diabetol. 40:118-122, 2003). Several lactic acid bacteria are able to display ferulic acid esterase (FAE) activity, suggesting that their probiotic activity could be, in part, mediated by the slow release of ferulic acid. In the present work, we describe the isolation of one strain identified as being Lactobacillus johnsonii that displayed strong FAE activity in stool samples from diabetes-resistant biobreeding rats. These animals are genetically susceptible to becoming diabetic but do not develop the disease. By using genomic analysis coupled to protein purification and catalytic screening, we were able to purify two proteins with FAE activity. The enzymes displayed 42% sequence identity and a broad range of substrate preferences. High affinities and catalytic efficiencies toward aromatic compounds such as ethyl ferulate (Km = 20 to 60 μM) and chlorogenic acid (Km = 10 to 50 μM) were observed. The strain isolated herein as well as the enzymes studied could be potentially useful for the formulation of probiotics to ameliorate diabetes symptoms. PMID:19502437

Biochemical properties of two cinnamoyl esterases purified from a Lactobacillus johnsonii strain isolated from stool samples of diabetes-resistant rats.

PubMed

Lai, Kin Kwan; Lorca, Graciela L; Gonzalez, Claudio F

2009-08-01

Cinnamic acids (i.e., ferulic and caffeic acids) that are esterified to the vegetable cell walls should be enzymatically released to be absorbed in a mammal's intestines. A low dosage of ferulic acid in rodent diets stimulates insulin production and alleviates symptoms caused by diabetes (M. Sri Balasubashini, R. Rukkumani, and V. P. Menon, Acta Diabetol. 40:118-122, 2003). Several lactic acid bacteria are able to display ferulic acid esterase (FAE) activity, suggesting that their probiotic activity could be, in part, mediated by the slow release of ferulic acid. In the present work, we describe the isolation of one strain identified as being Lactobacillus johnsonii that displayed strong FAE activity in stool samples from diabetes-resistant biobreeding rats. These animals are genetically susceptible to becoming diabetic but do not develop the disease. By using genomic analysis coupled to protein purification and catalytic screening, we were able to purify two proteins with FAE activity. The enzymes displayed 42% sequence identity and a broad range of substrate preferences. High affinities and catalytic efficiencies toward aromatic compounds such as ethyl ferulate (K(m) = 20 to 60 microM) and chlorogenic acid (K(m) = 10 to 50 microM) were observed. The strain isolated herein as well as the enzymes studied could be potentially useful for the formulation of probiotics to ameliorate diabetes symptoms.

Preventing non-alcoholic fatty liver disease through Lactobacillus johnsonii BS15 by attenuating inflammation and mitochondrial injury and improving gut environment in obese mice.

PubMed

Xin, Jinge; Zeng, Dong; Wang, Hesong; Ni, Xueqin; Yi, Dan; Pan, Kangcheng; Jing, Bo

2014-08-01

The increasing prevalence of obesity worldwide is associated with a parallel increase in non-alcoholic fatty liver disease (NAFLD). To investigate the effect of Lactobacillus johnsonii BS15 on NAFLD, 120 male ICR mice were randomly divided into four groups and administrated with BS15 (2 × 10(7) cfu/0.2 mL or 2 × 10(8) cfu/0.2 mL) or phosphate buffered saline (PBS) throughout a 17-week experimental period. The mice were fed with normal chow diet (NCD) 5 weeks before the experimental period. Afterward, with the exception of the PBS group, NCD was changed into high-fat diet (HFD) for the remaining experimental period. Results showed that BS15-treated HFD mice were protected from hepatic steatosis and hepatocyte apoptosis. BS15 exhibited a positive effect on liver lipid peroxidation through an anti-oxidative stress activity by enhancing the liver antioxidant defense system. In addition, BS15 inhibited the insulin resistance; decreased the mRNA levels of acetyl-CoA carboxylase 1, fatty acid synthase, and peroxisome proliferator-activated receptor γ; and increased the expression of the fasting-induced adipose factor in livers. Meanwhile, BS15 attenuated mitochondria abnormalities when the content of uncoupling protein-2 decreased and cytochrome c increased in NAFLD mice. BS15 also reduced the level of serum lipopolysaccharide in NAFLD mice by lowering the intestinal permeability and adjusting gut flora, followed by the downregulation of the TNFα mRNA level in liver and the serum level of C-reactive protein. These findings suggest that BS15 may be effective in preventing NAFLD induced by HFD.

Live Probiotic Lactobacillus johnsonii BS15 Promotes Growth Performance and Lowers Fat Deposition by Improving Lipid Metabolism, Intestinal Development, and Gut Microflora in Broilers.

PubMed

Wang, Hesong; Ni, Xueqin; Qing, Xiaodan; Zeng, Dong; Luo, Min; Liu, Lei; Li, Guangyao; Pan, Kangcheng; Jing, Bo

2017-01-01

Numerous studies have focused on the beneficial effects of probiotics in animals. Even so, additional information should be obtained about the mechanisms by which a useful probiotic strain successfully exerts such beneficial effects. In this study, we evaluated the effect of the dietary supplementation of both live and disrupted Lactobacillus johnsonii (LJ) strain BS15 in broilers at different ages. Specifically, growth performance, lipid metabolism, gut microbiota, intestinal development, and digestive ability of the broilers were assessed. A total of 180 1-day-old Cobb 500 chicks were randomly distributed into three groups. These chicks were fed diets supplemented with 1 × 10 6 colony-forming units (cfu) LJ per gram of feed (LJ group); 1 × 10 6 cfu disrupted LJ per gram of feed (D-LJ group); and de Man, Rogosa, and Sharpe liquid medium (control group), respectively, throughout a 42-day experimental period. The results demonstrated that LJ supplementation of feed had a positive effect on the average daily gain and starter feed conversion ratio. In addition, LJ supplementation of feed decreased serum triglyceride and low-density lipid cholesterol levels, as well as abdominal fat deposition. LJ also reduced the mRNA levels of lipoprotein lipase in adipose tissue and stearoyl-CoA desaturase-1 in the liver. LJ diminished the mRNA quantities of the sterol regulatory element binding protein-1c and fatty acid synthase, as well as increased the level of serum high-density lipid cholesterol. LJ increased the mRNA quantities of peroxisome proliferator-activated receptor α, acyl-CoA oxidase in the liver, and carnitine palmitoyltransferase-1. LJ also improved the intestinal development and digestive ability mainly by increasing the villus height/crypt depth ratio in the ileum. The probiotic increased the levels of epidermal growth factor and insulin-like growth factor-1, as well as the activities of trypsin and lipase in the jejunum and ileum. LJ exerted beneficial effects

Lactobacillus johnsonii N6.2 stimulates the innate immune response through Toll-like receptor 9 in Caco-2 cells and increases intestinal crypt Paneth cell number in biobreeding diabetes-prone rats.

PubMed

Kingma, Sandra D K; Li, Nan; Sun, Frank; Valladares, Ricardo B; Neu, Joe; Lorca, Graciela L

2011-06-01

Lactobacillus johnsonii (Ljo) N6.2 has been shown to mitigate the development of type 1 diabetes when administered to diabetes-prone rats. The specific mechanisms underlying this observed response remain under investigation. The objective of this study was to assess the effect of Ljo N6.2 on mucosal inflammatory response using differentiated Caco-2 monolayers. The mRNA expression levels of CCL20, CXCL8, and CXCL10 chemokines were determined by qRT-PCR. Ljo at 10(11) CFU/L induced a strong response in all chemokines examined. To assess the specific host-signaling pathways involved, we performed RT-PCR amplification of Toll-like receptors (TLR) and nucleotide-binding oligomerization domain-like receptors. TLR7 and TLR9 expression levels were induced 4.2- and 9-fold, respectively, whereas other TLR and nucleotide-binding oligomerization domain receptors were not modified. A similar effect was observed in Caco-2 monolayers treated with Ljo cell-free extract or purified nucleic acids (NA). Increased levels of IFN type 1 and IFN regulators Stat1 and IRF7 followed the upregulation of TLR9. Activation of TLR9 was also evidenced by increased Frizzled 5 expression in Ljo-treated Caco-2 cells and an increase in the number of Paneth cells in Ljo-fed, diabetes-prone rats. These results are in agreement with the polarizing-tolerizing mechanism recently described in which the apical stimulation of TLR9 in intestinal epithelial cells leads to a higher state of immunologic alertness. Furthermore, these results suggest that live probiotics could be, in the future, replaced with select cellular components.

Spin-split fermi surfaces in CexLa1-xB6 and PrxLa1-xB6

NASA Astrophysics Data System (ADS)

Isshiki, T.; Endo, M.; Sugi, M.; Kimura, N.; Nakamura, S.; Nojima, T.; Aoki, H.; Kunii, S.

2006-05-01

We have performed the dHvA measurements on CexLa1-xB6 and PrxLa1-xB6 compounds to study spin splitting of the Fermi surfaces. In PrB 6 we have found new frequency branches to confirm that the Fermi surface splits into up and down spin Fermi surfaces, whereas no spin splitting has been found for x=0.25,0.5,0.75. We have also found several new frequency branches in CeB6. The new frequency branches imply that the Fermi surfaces of up and down spin conduction electrons are significantly different in CeB6 as well as in PrB6.

La 1–xBi 1+xS 3 ( x ≈ 0.08): An n-Type Semiconductor

DOE PAGES

Han, Fei; Liu, Huimei; Malliakas, Christos D.; ...

2016-03-21

We study the new bismuth chalcogenide La 0.92Bi 1.08S 3 which crystallizes in the monoclinic space group C2/m with a = 28.0447(19) Å, b = 4.0722(2) Å, c = 14.7350(9) Å, and β = 118.493(5)°. The structure of La 0.92Bi 1.08S 3 is built of NaCl-type Bi 2S 5 blocks and BiS 4 and LaS 5 infinitely long chains, forming a compact three-dimensional framework with parallel tunnels. Optical spectroscopy and resistivity measurements reveal a semiconducting behavior with a band gap of ~1 eV and activation energy for transport of 0.36(1) eV. Thermopower measurements suggest the majority carriers of La 0.92Bimore » 1.08S 3 are electrons. Heat capacity measurements indicate no phase transitions from 2 to 300 K. Lastly, band structure calculations at the density functional theory level confirm the semiconducting nature and the indirect gap of La 0.92Bi 1.08S 3.« less

Diverse Responses to UV-B Radiation and Repair Mechanisms of Bacteria Isolated from High-Altitude Aquatic Environments▿

PubMed Central

Fernández Zenoff, V.; Siñeriz, F.; Farías, M. E.

2006-01-01

Acinetobacter johnsonii A2 isolated from the natural community of Laguna Azul (Andean Mountains at 4,560 m above sea level), Serratia marcescens MF42, Pseudomonas sp. strain MF8 isolated from the planktonic community, and Cytophaga sp. strain MF7 isolated from the benthic community from Laguna Pozuelos (Andean Puna at 3,600 m above sea level) were subjected to UV-B (3,931 J m−2) irradiation. In addition, a marine Pseudomonas putida strain, 2IDINH, and a second Acinetobacter johnsonii strain, ATCC 17909, were used as external controls. Resistance to UV-B and kinetic rates of light-dependent (UV-A [315 to 400 nm] and cool white light [400 to 700 nm]) and -independent reactivation following exposure were determined by measuring the survival (expressed as CFU) and accumulation of cyclobutane pyrimidine dimers (CPD). Significant differences in survival after UV-B irradiation were observed: Acinetobacter johnsonii A2, 48%; Acinetobacter johnsonii ATCC 17909, 20%; Pseudomonas sp. strain MF8, 40%; marine Pseudomonas putida strain 2IDINH, 12%; Cytophaga sp. strain MF7, 20%; and Serratia marcescens, 21%. Most bacteria exhibited little DNA damage (between 40 and 80 CPD/Mb), except for the benthic isolate Cytophaga sp. strain MF7 (400 CPD/Mb) and Acinetobacter johnsonii ATCC 17909 (160 CPD/Mb). The recovery strategies through dark and light repair were different in all strains. The most efficient in recovering were both Acinetobacter johnsonii A2 and Cytophaga sp. strain MF7; Serratia marcescens MF42 showed intermediate recovery, and in both Pseudomonas strains, recovery was essentially zero. The UV-B responses and recovery abilities of the different bacteria were consistent with the irradiation levels in their native environment. PMID:17056692

7. WEYMOUTH FILTRATION PLANT, BUILDING 1 INTERIOR: LA VERNE CONTROL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. WEYMOUTH FILTRATION PLANT, BUILDING 1 INTERIOR: LA VERNE CONTROL ROOM, REGULATES DISTRIBUTION OF WATER, CONTROLS POWER HOUSES. - F. E. Weymouth Filtration Plant, 700 North Moreno Avenue, La Verne, Los Angeles County, CA

Comparative assessment of canine-origin Lactobacillus johnsonii CPN23 and dairy-origin Lactobacillus acidophillus NCDC 15 for nutrient digestibility, faecal fermentative metabolites and selected gut health indices in dogs.

PubMed

Kumar, Sachin; Pattanaik, Ashok K; Sharma, Shalini; Gupta, Reema; Jadhav, Sunil E; Dutta, Narayan

2017-01-01

The present experiment was undertaken to validate a probiotic of canine origin for its potential use in dogs. A total of fifteen adult female Labrador dogs were allocated to three equal groups and fed a basal diet without probiotic (control) or with probiotic of either canine ( Lactobacillus johnsonii CPN23; cPRO) or dairy ( L. acidophilus NCDC 15; dPRO) origin for 9 weeks. The digestibility of most macronutrients remained similar among the groups; however, fibre digestibility was improved ( P  = 0·034) in dogs receiving cPRO. The faecal fermentative metabolites ammonia ( P   <  0·05) and lactate ( P  = 0·094) were altered favourably, indicating a positive influence of both probiotics. Faecal concentrations of acetate, propionate and butyrate were increased ( P   <  0·01) in both probiotic groups. However, improvements were higher in cPRO v . dPRO. The delayed-type hypersensitivity reaction to intradermal inoculation of phytohaemagglutinin-P was higher ( P  = 0·053) in cPRO as compared with control. The antibody response to sheep erythrocytes was, however, similar across the three groups. Overall, in dogs, the canine-origin probiotic was superior when compared with the dairy-origin probiotic.

Defect Structures of La1 - y Sr y F3 - y , La1 - y Ba y F3 - y , and Nd1 - y Ca y F3 - y ( y = 0.05, 0.10) Nonstoichiometric Tysonite Phases

NASA Astrophysics Data System (ADS)

Chernaya, T. S.; Verin, I. A.; Khrykina, O. N.; Bolotina, N. B.

2018-01-01

Characteristic features of defect structures of La1 - y Sr y F3 - y , La1 - y Ba y F3 - y , and Nd1 - y Ca y F3 - y ( y = 0.05, 0.10) nonstoichiometric phases of different compositions are determined from X-ray diffraction data. Interest in subtle details of their structure is determined by the possibility of ion transport over fluorine vacancies and by a strong compositional dependence of the ionic conductivity. The La0.95Sr0.05F2.95, La0.95Ba0.05F2.95, and Nd0.95Ca0.05F2.95 phases, as well as the La0.9Ba0.1F2.9 phase, crystallize as β-LaF3 (sp. gr. P3̅c1, Z = 6). The La0.9Sr0.1F2.9 and Nd0.9Ca0.1F2.9 phases lose their superstructure and are described by a cell whose volume is three times smaller (sp. gr. P63/ mmc, Z = 2). Defects of crystal structure R1 - y M y F3 - y are not exhausted by vacancies in fluorine positions. All crystals with a "large" cell are twinned according to the merohedral twin law. The majority of atomic positions in models with a "small" cell are split by group symmetry elements and are occupied statistically.

Stoichiometry dependence of potential screening at La ( 1 - δ ) Al ( 1 + δ ) O 3 / SrTiO 3 interfaces

DOE PAGES

Weiland, Conan; Sterbinsky, George E.; Rumaiz, Abdul K.; ...

2015-04-03

Hard x-ray photoelectron spectroscopy (HAXPES) and variable kinetic energy x-ray photoelectron spectroscopy (VKE-XPS) analyses have been performed on ten-unit-cell-thick La (1-δ)Al (1+δ)O₃ films, with La:Al ratios of 1.1, 1.0, and 0.9, deposited on SrTiO₃. Only Al-rich films are known to have a conductive interface. VKE-XPS, coupled with maximum entropy analysis, shows significant differences in the compositional depth profile among the Al-rich, La-rich, and stoichiometric films: significant La enrichment at the interface is observed in the La-rich and stoichiometric films, while the Al-rich film shows little to no intermixing. Additionally, the La-rich and stoichiometric films show a high concentration of Almore » at the surface, which is not observed in the Al-rich film. HAXPES valence band (VB) analysis shows a broadening of the VB for the Al-rich sample relative to the stoichiometric and La-rich samples. This broadening is consistent with an electric field across the Al-rich film. These results are consistent with a defect-driven electronic reconstruction.« less

Identification of Lactobacillus proteins with different recognition patterns between immune rabbit sera and nonimmune mice or human sera.

PubMed

Górska, Sabina; Buda, Barbara; Brzozowska, Ewa; Schwarzer, Martin; Srutkova, Dagmar; Kozakova, Hana; Gamian, Andrzej

2016-02-09

The genus Lactobacillus belongs to a large heterogeneous group of low G + C Gram-positive anaerobic bacteria, which are frequently used as probiotics. The health-beneficial effects, in particular the immunomodulation effect, of probiotics depend on the strain and dose used. Strain variations may be related to diversity of the cell surface architecture of bacteria and the ability to express specific antigens or secrete compounds. The use of Lactobacillus as probiotic requires a comprehensive understanding of its effect on host immune system. To evaluate the potential immunoreactive properties of proteins isolated from four Lactobacillus strains: L. johnsonii 142 and L. johnsonii 151, L. rhamnosus LOCK 0900 and L. casei LOCK 0919, the polyclonal sera obtained from mouse and human have been tested as well as with sera from rabbits immunized with whole lactobacilli cells. The reactivity of isolated proteins detected by SDS-PAGE and Western blotting was heterogeneous and varied between different serum samples. The proteins with the highest immunoreactivity were isolated, purified and sequenced, in particular the fractions were identified as phosphoglycerate kinase (L. johnsonii 142), glyceraldehyde 3-phosphate dehydrogenase (L. johnosnii 142, L. rhamnosus LOCK 0900), hypothetic protein JDM1_1307 (L. johnsonii 151) and fructose/tagatose-bisphosphate-aldolase (L. casei LOCK 0919). The different prevalence of reactions against tested antigens in rabbit, mouse and human sera may indicate significant differences in immune system and commensal cross-talk in these groups. The identification of immunoreactive lactobacilli proteins opens the possibility to use them as an antigens for development of vaccines.

Identification of genes associated with the long-gut-persistence phenotype of the probiotic Lactobacillus johnsonii strain NCC533 using a combination of genomics and transcriptome analysis.

PubMed

Denou, Emmanuel; Pridmore, Raymond David; Berger, Bernard; Panoff, Jean-Michel; Arigoni, Fabrizio; Brüssow, Harald

2008-05-01

Lactobacillus johnsonii strains NCC533 and ATCC 33200 (the type strain of this species) differed significantly in gut residence time (12 versus 5 days) after oral feeding to mice. Genes affecting the long gut residence time of the probiotic strain NCC533 were targeted for analysis. We hypothesized that genes specific for this strain, which are expressed during passage of the bacterium through the gut, affect the phenotype. When the DNA of the type strain was hybridized against a microarray of the sequenced NCC533 strain, we identified 233 genes that were specific for the long-gut-persistence isolate. Whole-genome transcription analysis of the NCC533 strain using the microarray format identified 174 genes that were strongly and consistently expressed in the jejunum of mice monocolonized with this strain. Fusion of the two microarray data sets identified three gene loci that were both expressed in vivo and specific to the long-gut-persistence isolate. The identified genes included LJ1027 and LJ1028, two glycosyltransferase genes in the exopolysaccharide synthesis operon; LJ1654 to LJ1656, encoding a sugar phosphotransferase system (PTS) transporter annotated as mannose PTS; and LJ1680, whose product shares 30% amino acid identity with immunoglobulin A proteases from pathogenic bacteria. Knockout mutants were tested in vivo. The experiments revealed that deletion of LJ1654 to LJ1656 and LJ1680 decreased the gut residence time, while a mutant with a deleted exopolysaccharide biosynthesis cluster had a slightly increased residence time.

1. Photocopy of photograph (original print on file at La ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. Photocopy of photograph (original print on file at La Grande District Office, La Grande, Oregon) No information about photographer or date OFFICE, SOUTHWEST FRONT - Union Ranger District Compound, Office, Fronting State Highway 203, at West edge of Union, Union, Union County, OR

Expression of p21Waf1/Cip1 and cyclin D1 is increased in butyrate-resistant HeLa cells.

PubMed

Derjuga, A; Richard, C; Crosato, M; Wright, P S; Chalifour, L; Valdez, J; Barraso, A; Crissman, H A; Nishioka, W; Bradbury, E M; Th'ng, J P

2001-10-12

Sodium butyrate induced cell cycle arrest in mammalian cells through an increase in p21Waf1/Cip1, although another study showed that this arrest is related to pRB signaling. We isolated variants of HeLa cells adapted to growth in 5 mm butyrate. One of these variants, clone 5.1, constitutively expressed elevated levels of p21Waf1/Cip1 when incubated in regular growth medium and in the presence of butyrate. Despite this elevated level of p21Waf1/Cip1, the cells continue to proliferate, albeit at a slower rate than parental HeLa cells. Western blot analyses showed that other cell cycle regulatory proteins were not up-regulated to compensate for the elevated expression of p21Waf1/Cip1. However, cyclin D1 was down-regulated by butyrate in HeLa cells but not in clone 5.1. We conclude that continued expression of cyclin D1 allowed clone 5.1 to grow in the presence of butyrate and elevated levels of p21Waf1/Cip1.

Superconductivity and strong intrinsic defects in LaPd1-xBi2

NASA Astrophysics Data System (ADS)

Han, Fei; Malliakas, Christos D.; Stoumpos, Constantinos C.; Sturza, Mihai; Claus, Helmut; Chung, Duck Young; Kanatzidis, Mercouri G.

2013-10-01

Two new phases LaPd1-xBi2 and CePd1-xBi2 were obtained by growing single crystals in Bi flux. They adopt the tetragonal ZrCuSi2-type structure and feature Bi-square nets and PbO-type PdBi layers with significant partial Pd occupancy. Bulk superconductivity at 2.1 K and metallic behavior above Tc are observed in LaPd1-xBi2. A small residual resistance ratio (RRR) indicates a strong scattering effect induced by the Pd vacancies, which implies an s-wave pairing symmetry in LaPd1-xBi2. The broadening of the resistivity transition was measured under different magnetic fields demonstrating a high upper critical field of 3 T. Hall effect measurements reveal dominantly electron-like charge carriers and single-band transport behavior in LaPd1-xBi2. The paramagnetic CePd1-xBi2 is nonsuperconducting but shows antiferromagnetic ordering below 6 K.

Properties of different lactic acid bacteria isolated from Apis mellifera L. bee-gut.

PubMed

Carina Audisio, M; Torres, María J; Sabaté, Daniela C; Ibarguren, Carolina; Apella, María C

2011-01-20

Eight strains belonging to Lactobacillus spp. and five to Enterococcus spp. were isolated from the gut of worker Apis mellifera L. bees. Studies based on 16S rRNA sequencing revealed that AJ5, IG9, A15 and CRL1647 strains had a 99% identity with Lactobacillus johnsonii, while SM21 showed a 99% similarity with Enterococcus faecium. L. johnsonii CRL1647, AJ5 and IG9 were high lactic acid producers (values were between 177 and 275 mM), and in vitro they inhibited different human food-borne pathogens and Paenibacillus larvae, the American foulbrood agent. This bacterium was the most sensitive to the lactic acid effect being inhibited by 44 mM of this metabolite. L. johnsonii CRL1647, AJ5 and IG9 also presented important surface properties. These cells showed between 77% and 93% of auto-aggregation. The preliminary study of the chemical nature of the aggregating factors revealed that the molecules involved in the surface of each L. johnsonii strain were quite complex; and something of a peptidic nature was mainly involved. E. faecium SM21 produced bacteriocin-like compounds with anti-Listeria effects. Furthermore, a band close to 6.0-7.5 kDA was detected by SDS-PAGE studies, and the entA, B and P structural genes were amplified by PCR reactions. For the first time, bee-gut associated L. johnsonii and E. faecium strains have been isolated, identified, cultivated and some of their functional properties reported. Copyright © 2010 Elsevier GmbH. All rights reserved.

Local Matrix-Cluster Interactions In La1-x SrxCoO3.

NASA Astrophysics Data System (ADS)

Giblin, Sean; Terry, Ian; Boothroyd, Andrew; Prabhakaran, Dharmalingiam; Wu, Jing; Leighton, Chris

2006-03-01

Magneto-electronic phase separation plays an integral part in many recent advances in the understanding of correlated electron systems. We have studied the magnetically phase separated material La1-x SrxCoO3 and the parent compound LaCoO3, using muon spectroscopy and magnetic susceptibility measurements. The muon as a local magnetic probe is sensitive to the magnetic field distribution in LaCoO3 in the LS state, which is a direct consequence of magnetic excitons. We believe that these excitons are interacting with the Co ions undergoing the known thermally induced spin transition. By directly comparing the results of the parent compound with La1-x SrxCoO3 we can observe the hole-rich ferromagnetic clusters interacting with the neighboring hole poor matrix for low x. This mechanism, detected here for the first time, may play an important role in the rich electrical and magnetic properties of La1-x SrxCoO3.

RPA-1 from Leishmania amazonensis (LaRPA-1) structurally differs from other eukaryote RPA-1 and interacts with telomeric DNA via its N-terminal OB-fold domain.

PubMed

Pavani, R S; Fernandes, C; Perez, A M; Vasconcelos, E J R; Siqueira-Neto, J L; Fontes, M R; Cano, M I N

2014-12-20

Replication protein A-1 (RPA-1) is a single-stranded DNA-binding protein involved in DNA metabolism. We previously demonstrated the interaction between LaRPA-1 and telomeric DNA. Here, we expressed and purified truncated mutants of LaRPA-1 and used circular dichroism measurements and molecular dynamics simulations to demonstrate that the tertiary structure of LaRPA-1 differs from human and yeast RPA-1. LaRPA-1 interacts with telomeric ssDNA via its N-terminal OB-fold domain, whereas RPA from higher eukaryotes show different binding modes to ssDNA. Our results show that LaRPA-1 is evolutionary distinct from other RPA-1 proteins and can potentially be used for targeting trypanosomatid telomeres. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Conséquences macroéconomiques du vieillissement de la population 1

PubMed Central

Lee, Ronald; Mason, Andrew

2017-01-01

Résumé La baisse de la fécondité et l’allongement de la durée de la vie amènent au vieillissement de la population et au ralentissement ou même à la baisse de la croissance démographique. Tandis que le ralentissement de la croissance démographique réduit la nécessité d’épargner, le vieillissement de la population impose des coûts liés à la dépendance des personnes âgées qui sont particulièrement lourds pour le secteur public. Le taux de fécondité est-il trop faible ? Le projet des Comptes de transferts nationaux (National Transfer Accounts ou NTA) fournit des données permettant de quantifier les coûts liés à la dépendance. Au vu de la répartition par âge actuelle des impôts et prestations dans les pays à revenu élevé et à revenu moyen supérieur, un taux d’environ trois naissances par femme permettrait de maximiser le ratio de soutien public. Les profils d’âge inclusifs de consommation et de revenus du travail sont toutefois plus pertinents en termes de niveau de vie. Les ratios de soutien correspondants sont maximisés par un taux de fécondité légèrement supérieur à deux naissances par femme. En allant un peu plus loin et en prenant en compte la baisse de l’épargne, un taux égal à 1,5 naissance par femme dans les pays à revenu moyen supérieur et à 1,8 naissance par femme dans les pays riches industrialisés permettrait de maximiser le niveau de vie. Au sein d’économies ouvertes, ces résultats seraient légèrement différents. Par ailleurs, la prise en compte du capital humain influerait également quelque peu sur ces résultats. PMID:28804226

Les formes graves de la grippe A(H1N1) 2009 chez la femme enceinte: expérience du centre hospitalier universitaire de Fès, Maroc et revue de la littérature

PubMed Central

Adnane Berdai, Mohamed; Labib, Smael; Harandou, Mustapha

2012-01-01

Introduction Le but de cette étude est de décrire les caractéristiques épidémiologiques, cliniques, paracliniques ainsi que l’évolution des femmes enceintes ou en post partum atteintes de formes graves de Grippe A(H1N1) 2009. Méthodes C’est une étude prospective observationnelle monocentrique, menée au sein de notre service de réanimation mère et enfant au centre hospitalier universitaire Hassan II à Fès, sur une période de 3 mois, allant de novembre 2009 à janvier 2010. Résultats L’âge moyen était de 28 ans, dans 85% des cas la grossesse se situaient au troisième trimestre, le syndrome grippal était constant, la SpO2 initiale était en moyenne de 86%. A la radiographie thoracique, un syndrome alvéolaire bilatéral était toujours présent. L’infection virale était confirmée dans tous les cas par la polymerase chain reaction. Chez 3 patientes la PaO2/FiO2 était inférieure à 300. L’Oseltamivir était l’antiviral utilisé chez toutes les parturientes. Un syndrome de détresse respiratoire aigu a été développé chez 28% des parturientes, elles ont été ventilées artificiellement avec des niveaux de pressions expiratoires positives à 14 +/- 1 cmH2O. L’évolution était favorable dans 71% des cas, cependant, 2 décès ont été déplorés. Conclusion Les résultats rejoignent les données de la littérature, à savoir, un risque accru pour la femme enceinte de développer une forme grave, une présentation clinique similaire au reste de la population, l’intérêt de la vaccination et d’un traitement antiviral précoce et le rôle de l’ECMO dans le traitement des hypoxémies réfractaires. PMID:22514770

Relations de Dispersion et Diffusion des Glueballs et des Mesons dans la Theorie de Jauge U(1)(2+1) Compacte

NASA Astrophysics Data System (ADS)

Ahmed, Chaara El Mouez

Nous avons etudie les relations de dispersion et la diffusion des glueballs et des mesons dans le modele U(1)_{2+1} compact. Ce modele a ete souvent utilise comme un simple modele de la chromodynamique quantique (QCD), parce qu'il possede le confinement ainsi que les etats de glueballs. Par contre, sa structure mathematique est beaucoup plus simple que la QCD. Notre methode consiste a diagonaliser l'Hamiltonien de ce modele dans une base appropriee de graphes et sur reseau impulsion, afin de generer les relations de dispersion des glueballs et des mesons. Pour la diffusion, nous avons utilise la methode dependante du temps pour calculer la matrice S et la section efficace de diffusion des glueballs et des mesons. Les divers resultats obtenus semblent etre en accord avec les travaux anterieurs de Hakim, Alessandrini et al., Irving et al., qui eux, utilisent plutot la theorie des perturbations en couplage fort, et travaillent sur un reseau espace-temps.

Degenerate p-type conductivity in wide-gap LaCuOS1-xSex (x=0-1) epitaxial films

NASA Astrophysics Data System (ADS)

Hiramatsu, Hidenori; Ueda, Kazushige; Ohta, Hiromichi; Hirano, Masahiro; Kamiya, Toshio; Hosono, Hideo

2003-02-01

Epitaxial films of LaCuOS1-xSex (x=0-1) solid solution were grown on MgO (001) substrates and their electrical and optical properties were examined. Sharp emission due to room-temperature exciton with binding energy of ˜50 meV is observed for all x values. Hall mobility becomes large with an increase in the Se content and it reaches 8.0 cm2V-1s-1 in LaCuOSe, a comparable value to that of p-type GaN:Mg. Doping of Mg2+ ions at La3+ sites enhances a hole concentration up to 2.2×1020 cm-3, while maintaining the Hall mobility as large as 4.0 cm2V-1s-1. Consequently, a degenerate p-type electrical conduction with a conductivity of 140 S cm-1 was achieved.

[Effect of NOR1 gene knockdown on the biological behavior of HeLa cells].

PubMed

Tan, Yixin; Li, Wenjuan; Yi, Mei; Wang, Wei; Zheng, Pan; Zhang, Haijing; Xiang, Bo; Li, Guiyuan

2014-08-01

To explore the effect of the oxidored nitro domain containing protein 1 (NOR1) gene knockdown on the biological behavior of HeLa cells in cervical carcinoma. The recombinant plasmids pSUPER-shNOR1-1, pSUPER-shNOR1-2 and pSUPERscramble, which targeted to NOR1 gene, were constructed by pSUPER.neo+GFP vector, transfected into HeLa cells respectively using Lipofectamine 2000 reagent, and followed by G418 selection. The expression level of NOR1 mRNA and protein were determined by RT-PCR and Western blotting, respectively. Methyl thiazolyl tetrazolium (MTT) assay was performed to determine the growth curve of cell viability. The stable transfectants were treated with H₂O₂ and cell apoptosis was determined by Hoechst 33258 staining and terminal deoxynucleotidyl transferasemediated dUTP nick end labeling (TUNEL) assay. The expression levels of Bcl-2, cleaved caspase 9 and poly ADP-ribose polymerase (PARP) were measured by Western blot. NOR1- knockdown HeLa cells were successfully constructed by transfection of pSUPER-shNOR1-1 or pSUPER-shNOR1-2 plasmids into HeLa cells. MTT assay showed that the silence of endogenous NOR1 in HeLa cells could lead to the increase in cell viability and proliferation, and the inhibition of H₂O₂-induced apoptosis compared with the negative control. Western blot showed that the expression level of active caspase 9 and cleaved PARP was inhibited in NOR1-knockdown cells when they were treated with H₂O₂ while the expression level of Bcl-2 protein increased. Silence of endogenous NOR1 facilitates the cell viability and growth of HeLa cells, and attenuates HeLa cells apoptosis induced by H₂O₂, which might be mediated by up-regulation of Bcl-2 level and down-regulation of the cleaved caspase 9 cascade.

Crystal structure and electrical conductivity of lanthanum-calcium chromites-titanates La 1-xCa xCr 1-yTi yO 3-δ ( x=0-1, y=0-1)

NASA Astrophysics Data System (ADS)

Vashook, V.; Vasylechko, L.; Zosel, J.; Gruner, W.; Ullmann, H.; Guth, U.

2004-10-01

Five series of perovskite-type compounds in the system La1-xCaxCr1-yTiyO3 with the nominal compositions y = 0 , x = 0 - 0.5 ; y = 0.2 , x = 0.2 - 0.8 ; y = 0.5 , x = 0.5 - 1.0 ; y = 0.8 , x = 0.6 - 1.0 and y = 1 , x = 0.8 - 1 were synthesized by a ceramic technique in air (final heating 1350 °C). On the basis of the X-ray analysis of the samples with (Ca/Ti)⩾1, the phase diagram of the CaTiO3-LaCrIIIO3-CaCrIVO3 quasi-ternary system was constructed. Extended solid solution with a wide homogeneity range is formed in the quasi-ternary system CaCrIVO3-CaTiO3-LaCrIIIO3. The solid solution La(1-x‧-y)Ca(x‧+y)CrIVx‧CrIII(1-x‧-y)TiyO3 exists by up to 0.6-0.7 mol fractions of CaCrIVO3 (x‧ < 0.6 - 0.7) at the experimental conditions. The crystal structure of the compounds is orthorhombic in the space group Pbnm at room temperature. The lattice parameters and the average interatomic distances of the samples within the solid solution ranges decrease uniformly with increasing Ca content. Outside the quasi-ternary system, the nominal compositions La0.1Ca0.9TiO3, La0.2Ca0.8TiO3, La0.4Ca0.6Cr0.2Ti0.8O3 and La0.3Ca0.7Cr0.2Ti0.8O3 in the system La1-xCaxCr1-yTiyO3 were found as single phases with an orthorhombic structure. In the temperature range between 850 and 1000 °C, the synthesized single-phase compositions are stable at pO2=6×10-16-0.21×105 Pa. Oxygen stoichiometry and electrical conductivity of the separate compounds were investigated as functions of temperature and oxygen partial pressure. The chemical stability of these oxides with respect to oxygen release during thermal dissociation decreases with increasing Ca-content. At 900 °C and oxygen partial pressure 1×10-15-0.21×105 Pa, the compounds with x > y (acceptor doped) are p-type semiconductors and those with x < y (donor doped) and x = y are n-type semiconductors. The type and level of electrical conductivity are functions of the concentration ratios of cations occupying the B-sites of the perovskite

La2/3Sr1/3MnO3-La0.1Bi0.9MnO3 heterostructures for spin filtering

NASA Astrophysics Data System (ADS)

Gajek, M.; Bibes, M.; Varela, M.; Fontcuberta, J.; Herranz, G.; Fusil, S.; Bouzehouane, K.; Barthélémy, A.; Fert, A.

2006-04-01

We have grown heterostructures associating half-metallic La2/3Sr1/3MnO3 (LSMO) bottom electrodes and ferromagnetic La0.1Bi0.9MnO3 (LBMO) tunnel barriers. The layers in the heterostructures have good structural properties and top LBMO films (4 nm thick) have a very low roughness when deposited onto LSMO/SrTiO3(1.6 nm) templates. The LBMO films show an insulating behavior and a ferromagnetic character that are both preserved down to very low thicknesses. They are thus suitable for being used as tunnel barriers. Spin-dependent transport measurements performed on tunnel junctions defined from LSMO/SrTiO3/LBMO/Au samples show a magnetoresistance of up to ~90% at low temperature and bias. This evidences a spin-filtering effect by the LBMO layer, with a spin-filtering efficiency of ~35%.

Regulando la Enfermedad a través de la Definición y la Restricción: Profesionales de la Salud Hablan sobre el VIH/SIDA1

PubMed Central

Rivera, Souhail Malavé; Díaz, Nelson Varas

2009-01-01

Resumen Las profesiones de la salud tienen un papel social dual. Por un lado, velan por el mantenimiento de la salud de la población protegiendo el bien común. Por el otro, dictaminan las formas saludables, y por lo tanto socialmente apropiadas, de ser, actuar y pensar. Este último papel, está más ligado al control social de la población que a una preocupación altruista hacia la misma. A través de esta supervisión y control, se construyen los sujetos a los cuales todos/as debemos aspirar a ser para gozar de aceptación social. Los/as profesionales de la salud han jugado un rol protagónico en dicho proceso, siendo los agentes que delimitan y definen lo que es enfermo vs. saludable, útil vs. inútil, apropiado vs. inapropiado. En el caso de la epidemia del VIH, este esfuerzo se ha hecho cada vez más vigente ya que estos/as profesionales juegan un papel importante en el tratamiento de las personas que viven con VIH/SIDA (PVVS). Sin embargo, su función está plasmada de definiciones que sirven para criminalizar a las PVVS. El objetivo de este estudio fue explorar la manera en que una muestra de profesionales de la salud en Puerto Rico construyen a las PVVS. Con este propósito, entrevistamos 80 profesionales de la salud y estudiantes de estas profesiones. Estas entrevistas fueron grabadas, transcritas y sometidas a un análisis de discurso. Los resultados reflejaron que según las personas participantes: 1) la PVVS no es una persona “normal” o funcional bajo los estándares sociales debido a que su salud no se los permite, 2) representa una carga para la sociedad incluyendo familiares, amigos/as, el mundo del trabajo, e incluso para el gobierno, 3) debe ser vigilada porque representa un riesgo para la persona seronegativa que es descrita como saludable y productiva, y 4) necesita que su salud y conducta sexual sean controladas por vía legal y/o por las personas que representan las instituciones sociales, como lo son los/as profesionales de la salud

NMR study of spin fluctuations and superconductivity in LaFeAsO1-xHx

NASA Astrophysics Data System (ADS)

Fujiwara, Naoki; Sakurai, Ryosuke; Iimura, Soushi; Matsuishi, Satoru; Hosono, Hideo; Yamakawa, Yoichi; Kontani, Hiroshi

2013-03-01

We have performed NMR measurements in LaFeAsO1-xHx, an isomorphic compound of LaFeAsO1-xFx. LaFeAsO1-xHx is most recently known for having double superconducting (SC) domes on H doping. LaFeAsO1-xHx is an electron- doped system, and protons act as H-1 as well as F-1. The first SC dome is very similar between F and H doping, suggesting that H doping supplies the same amount of electrons as F doping. Interestingly, an excess amount of H up to x=0.5 can be replaced with O2-. In the H-overdoped regime (x > 0 . 2), LaFeAsO1-xHx undergoes the second superconducting state. We measured the relaxation rate of LaFeAsO1-xHx for x=0.2 and 0.4, and fond an anomalous electronic state; spin fluctuations measured from 1 /T1 T is enhanced with increasing the doping level from x = 0 . 2 to 0.4. The enhancement of spin fluctuations with increasing carrier doping is a new phenomenon that has not observed in LaFeAsO1-xFx in which the upper limit of the doping level is at most x = 0 . 2 . We will discuss the phenomenon in relation to superconductivity. Grant (KAKENHI 23340101) from the Ministry of Education, Sports and Science, Japan

Pressure-induced amorphization of La{sub 1/3}TaO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noked, O., E-mail: noked@bgu.ac.il; Physics Department, Ben-Gurion University, Beer Sheva 84105; Melchior, A.

2013-06-15

La{sub 1/3}TaO{sub 3}, an A-site cation deficient perovskite, has been studied under pressure by synchrotron X-ray powder diffraction and Raman spectroscopy. It undergoes irreversible pressure induced amorphization at P=18.5 GPa. An almost linear unit cell volume decrease vs. pressure is observed from ambient pressure up to the phase transition. The Raman spectroscopy also shows amorphization at the same pressure, with positive shifts of all modes as a function of pressure. The pressure dependence of the E{sub g} and A{sub 1g} Raman modes arising from the octahedral oxygen network is discussed. - Graphical abstract: La{sub 1/3}Tao{sub 3} exhibits linear pressure–volume relationmore » until irreversible pressure induced amorphization at 18.5 Gpa. - Highlights: • La{sub 1/3}TaO{sub 3} has been studied under pressure by synchrotron XRD and Raman spectroscopy. • La{sub 1/3}TaO{sub 3} undergoes irreversible pressure induced amorphization around 18.5 GPa. • The transition is manifested in both XRD and Raman measurements. • A linear P–V relation is observed from ambient pressure up to the phase transition.« less

Lamprey immune protein-1 (LIP-1) from Lampetra japonica induces cell cycle arrest and cell death in HeLa cells.

PubMed

Chi, Xiaoyuan; Su, Peng; Bi, Dan; Tai, Zhao; Li, Yingying; Pang, Yue; Li, Qingwei

2018-04-01

The lamprey (Lampetra japonica), a representative of the jawless vertebrates, is the oldest extant species in the world. LIP-1, which has a jacalin-like domain and an aerolysin pore-forming domain, has previously been identified in Lampetra japonica. However, the structure and function of the LIP-1 protein have not been described. In this study, the LIP-1 gene was overexpressed in HeLa cells and H293T cells. The results showed that the overexpression of LIP-1 in HeLa cells significantly elevated LDH release (P < 0.05), phosphatidylserine exposure and ROS accumulation. The overexpression of LIP-1 also had remarkable effects on the organelles in HeLa cells, while it had no effect on H293T cell organelles. Array data indicated that overexpression of LIP-1 primarily upregulated P53 signaling pathways in HeLa cells. Cell cycle assay results confirmed that LIP-1 caused arrest in the G 2 /M phase of the cell cycle in HeLa cells. In summary, our findings provide insights into the function and characterization of LIP-1 genes in vertebrates and establish the foundation for further research into the biological function of LIP-1. Our observations suggest that this lamprey protein has the potential for use in new applications in the medical field. Copyright © 2018. Published by Elsevier Ltd.

Evaluation of the LA 1 bridge at the Morganza flood control structure.

DOT National Transportation Integrated Search

2010-11-01

This technical assistance report documents the investigation conducted by the Louisiana Transportation : Research Center (LTRC) of the LA 1 Bridge located at the flood control structure near Morganza, LA. : The in-place condition of the bridge deck s...

Evaluation of the LA 1 bridge at the Morganza flood control structure.

DOT National Transportation Integrated Search

2010-11-01

This technical assistance report documents the investigation conducted by the Louisiana Transportation Research Center (LTRC) of the LA 1 Bridge located at the flood control structure near Morganza, LA. The in-place condition of the bridge deck showe...

Inactivation of Gram-negative and Gram-positive bacteria in red cell concentrates using INACTINE PEN110 chemistry.

PubMed

Zavizion, B; Serebryanik, D; Chapman, J; Alford, B; Purmal, A

2004-10-01

The risk of transfusion-transmitted bacterial infections as a result of the presence of bacteria in blood is one of the major concerns in transfusion medicine. The purpose of this study was to investigate whether bacteria inoculated into red blood cell concentrates can be inactivated by the INACTINE PEN110 pathogen-reduction process. Four bacterial species were chosen for the study: anaerobic Gram-positive Clostridium perfringens and Propionibacterium acnes, known to be transfusion-transmitted; and two Gram-negative species, Acinetobacter johnsonii and Acinetobacter lwoffii, recently reported to be a common cause of transfusion-associated infections in Europe. Identical units of leucoreduced red cell concentrates were inoculated with A. johnsonii, A. lwoffii, C. perfringens, or P. acnes. The 4 degrees C control units were put on storage immediately after receiving the spike. The test units were subjected to PEN110 treatment and then stored. The bacterial titre in all units was monitored during a 6-week storage period. The PEN110 inactivation of all tested bacterial strains was time- and titre-dependent. For A. johnsonii and A. lwoffii, no viable bacteria were detected in the units spiked with up to 10(4) colony-forming units (CFU)/ml and treated with PEN110. For red cell units spiked with 10(4)-10(5) CFU/ml of C. perfringens and P. acnes, no viable bacteria were detected in the units treated with PEN110. In control units, there was a gradual decrease in A. johnsonii, A. lwoffii and C. perfringens titres during cold storage, while P. acnes titres remained stable. The PEN110 pathogen-reduction process was demonstrated to inactivate high titres of A. johnsonii, A. lwoffii, C. perfringens and P. acnes in red cell concentrates.

The effects of Tb substitution for La on the magnetic properties of LaFe11.5Si1.5 compound

NASA Astrophysics Data System (ADS)

Imam, H.; Zhang, H. G.; Xu, L.; Zhao, J. L.; Gao, X. X.; Yue, M.

2018-05-01

The structural and magnetic properties of La1-yTbyFe11.5Si1.5 compounds have been investigated. The substituted 5 percent of Tb has remarkably increased the maximum entropy change (-ΔSM) to a value of 25.2 J/kg·K. However, a further increase of Tb leads to a monotonous decrease in the entropy change, mainly due to phase separation. The Tb substitution also can lower the thermal and magnetic hysteresis loss of the system. Another feature of this replacement is that, with Tb content higher than 10 percent, the Curie temperature (TC) starts to increase and reaches 197 K when 30 percent of La is substituted. These results indicate that La1-yTbyFe11.5Si1.5 may be a promising candidate for magnetic refrigeration material in certain temperature range.

Perovskite-based heterostructures integrating ferromagnetic-insulating La0.1Bi0.9MnO3

NASA Astrophysics Data System (ADS)

Gajek, M.; Bibes, M.; Barthélémy, A.; Varela, M.; Fontcuberta, J.

2005-05-01

We report on the growth of thin films and heterostructures of the ferromagnetic-insulating perovskite La0.1Bi0.9MnO3. We show that the La0.1Bi0.9MnO3 perovskite grows single phased, epitaxially, and with a single out-of-plane orientation either on SrTiO3 substrates or onto strained La2/3Sr1/3MnO3 and SrRuO3 ferromagnetic-metallic buffer layers. We discuss the magnetic properties of the La0.1Bi0.9MnO3 films and heterostructures in view of their possible potential as magnetoelectric or spin-dependent tunneling devices.

House dust exposure mediates gut microbiome Lactobacillus enrichment and airway immune defense against allergens and virus infection.

PubMed

Fujimura, Kei E; Demoor, Tine; Rauch, Marcus; Faruqi, Ali A; Jang, Sihyug; Johnson, Christine C; Boushey, Homer A; Zoratti, Edward; Ownby, Dennis; Lukacs, Nicholas W; Lynch, Susan V

2014-01-14

Exposure to dogs in early infancy has been shown to reduce the risk of childhood allergic disease development, and dog ownership is associated with a distinct house dust microbial exposure. Here, we demonstrate, using murine models, that exposure of mice to dog-associated house dust protects against ovalbumin or cockroach allergen-mediated airway pathology. Protected animals exhibited significant reduction in the total number of airway T cells, down-regulation of Th2-related airway responses, as well as mucin secretion. Following dog-associated dust exposure, the cecal microbiome of protected animals was extensively restructured with significant enrichment of, amongst others, Lactobacillus johnsonii. Supplementation of wild-type animals with L. johnsonii protected them against both airway allergen challenge or infection with respiratory syncytial virus. L. johnsonii-mediated protection was associated with significant reductions in the total number and proportion of activated CD11c(+)/CD11b(+) and CD11c(+)/CD8(+) cells, as well as significantly reduced airway Th2 cytokine expression. Our results reveal that exposure to dog-associated household dust results in protection against airway allergen challenge and a distinct gastrointestinal microbiome composition. Moreover, the study identifies L. johnsonii as a pivotal species within the gastrointestinal tract capable of influencing adaptive immunity at remote mucosal surfaces in a manner that is protective against a variety of respiratory insults.

House dust exposure mediates gut microbiome Lactobacillus enrichment and airway immune defense against allergens and virus infection

PubMed Central

Fujimura, Kei E.; Demoor, Tine; Rauch, Marcus; Faruqi, Ali A.; Jang, Sihyug; Johnson, Christine C.; Boushey, Homer A.; Zoratti, Edward; Ownby, Dennis; Lukacs, Nicholas W.; Lynch, Susan V.

2014-01-01

Exposure to dogs in early infancy has been shown to reduce the risk of childhood allergic disease development, and dog ownership is associated with a distinct house dust microbial exposure. Here, we demonstrate, using murine models, that exposure of mice to dog-associated house dust protects against ovalbumin or cockroach allergen-mediated airway pathology. Protected animals exhibited significant reduction in the total number of airway T cells, down-regulation of Th2-related airway responses, as well as mucin secretion. Following dog-associated dust exposure, the cecal microbiome of protected animals was extensively restructured with significant enrichment of, amongst others, Lactobacillus johnsonii. Supplementation of wild-type animals with L. johnsonii protected them against both airway allergen challenge or infection with respiratory syncytial virus. L. johnsonii-mediated protection was associated with significant reductions in the total number and proportion of activated CD11c+/CD11b+ and CD11c+/CD8+ cells, as well as significantly reduced airway Th2 cytokine expression. Our results reveal that exposure to dog-associated household dust results in protection against airway allergen challenge and a distinct gastrointestinal microbiome composition. Moreover, the study identifies L. johnsonii as a pivotal species within the gastrointestinal tract capable of influencing adaptive immunity at remote mucosal surfaces in a manner that is protective against a variety of respiratory insults. PMID:24344318

Thermoelectric properties of the ceramic oxide Sr1- x La x TiO3

NASA Astrophysics Data System (ADS)

Mahmud, Iqbal; Yoon, Man-Soon; Kim, Il-Ho; Choi, Moon-Kwan; Ur, Soon-Chul

2016-01-01

The effect of lanthanum on the electric and the thermoelectric properties of the ceramic oxide Sr1- x La x TiO3 (where x = 0.0, 0.04, 0.06, 0.08 and 0.12 mole) have been studied. La-doped SrTiO3 was prepared by using the conventional mixed-oxide reaction method. XRD patterns indicated that almost all the La atoms incorporated into the SrTiO3 crystal provided charge carriers. The lattice parameter increases with increasing La doping content. The relative densities of all the samples varied from 89.6% to 94.8%. The electrical conductivity increased with La doping up to 0.08 moles and then decreased as the content of La was increased above 0.08 moles. The thermal conductivity decreased with increasing La content. The largest absolute value of the Seebeck coefficient, 394 μVK-1 at 973 K, was observed at x = 0.04. The Sr0.92La0.08TiO3 sample showed its maximum electrical conductivity at 773 K and its largest ZT value of 0.20 at 973 K.

Appearance of the octupole ordered phase IV in CexLa1 -x B6

NASA Astrophysics Data System (ADS)

Sera, M.; Kunimori, K.; Matsumura, T.; Kondo, A.; Tanida, H.; Tou, H.; Iga, F.

2018-05-01

We investigated the physical properties of CexLa1 -xB6 at x ˜0.8 , below which the Tβ-type antiferro-octupole (AFO) ordered phase IV appears as a result of the larger suppression rate of TQ than TN by La doping. The most important result is that while the peak of the specific heat at TQ is rapidly suppressed and broadened by La doping, that at TIV is sharp and large. This indicates that although the Tβ-AFO order in the phase IV is robust against the local lattice distortion induced by La doping, the Ox y-type antiferroquadrupole (AFQ) ordered phase II is very weak. The Tx y z-AFO interaction is robust against La doping from the observation of the pronounced enhancement of TQ even in a small x region. Based on these La-doping effect of the multipole interactions, we carried out the mean-field calculation for the four-sublattice model to reproduce the magnetic phase diagrams of CexLa1 -xB6 . Based on the calculated results, we propose that the small splitting of the quartet is induced by La doping in phase I to explain the magnetic phase diagram for x <0.65 . We could obtain the calculated results roughly consistent with the experimental results, although there appear new problems. We classified the mechanisms of the four different types of the competition among the four interactions with roughly the same magnitude, which induce the interesting and complicated properties in CexLa1 -xB6 .

Thermodynamic properties of Ba{sub 1-x}La{sub x}CoO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaur, N. K., E-mail: srl-nkgaur@yahoo.co.in; Thakur, Rasna, E-mail: rasnathakur@yahoo.com; Thakur, Rajesh K., E-mail: thakur.rajesh2009@gmail.com

2016-05-06

We have predicted the thermodynamic behavior of Ba{sub 1-x}La{sub x}CoO{sub 3} family at temperature 1K≤T≤300K using the Modified Rigid Ion Model (MRIM). The specific heat of BaCoO{sub 3} with La doping in the perovskite structure at A-site has been reported. Also, the cohesive energy (ϕ), molecular force constant (f), Reststrahlen frequency (υ), Debye temperature (θ{sub D}), specific heat (C) and Gruneisen parameter (γ) of Ba{sub 1-x}La{sub x}CoO{sub 3} compounds are discussed.

Nanocrystalline Ce1- x La x O2- δ Solid Solutions Synthesized by Hydrolyzing and Oxidizing

NASA Astrophysics Data System (ADS)

Hou, Xueling; Xue, Yun; Han, Ning; Lu, Qianqian; Wang, Xiaochen; Phan, Manh-Huong; Zhong, Yunbo

2016-05-01

We undertook a novel batch production approach for the synthesis of CeO2 nanopowders doped with rare earth elements. Solid solution nanopowders of Ce1- x La x O2- δ ( x = 0.15) were successfully synthesized in a large-scale and low-cost production by hydrolyzing and oxidizing Ce-La-C alloys at room temperature and subsequent calcining of their powders at different temperatures (873-1073 K) for 1 h. The Ce-La-C alloys were prepared in a vacuum induction melting furnace. The final products were characterized by x-ray diffraction, transmission electron microscopy, Brunner-Emmet-Teller (BET) surface area analyzer, and Raman spectroscopy. The calculated lattice parameters of the cubic fluorite-type phase of CeO2 tended to increase when La3+ was incorporated into CeO2. The F 2g band shift and the absence of a peak corresponding to La2O3 in the Raman spectra consistently confirmed the incorporation of the La3+ ion into CeO2, and the formation of Ce1- x La x O2- δ solid solutions as manifested by increased oxygen vacancy defects. High-quality Ce1- x La x O2- δ nanopowders of ~10-15 nm diameter with a high BET surface area of ~77 m2 g-1 were obtained. The average crystallite size of Ce1- x La x O2- δ was found to be smaller than that of CeO2 for the same calcination temperature of 1073 K, demonstrating that the introduction of La3+ into CeO2 can stabilize the host lattice and refine the grain size at high temperatures.

Photoemission study of the electronic structure (Pr 0.2La 0.8)(Ba 1.875La 0.125)Cu 3O 7- gd

NASA Astrophysics Data System (ADS)

Lindberg, P. A. P.; Shen, Z.-X.; Lindau, I.; Spicer, W. E.; Mitzi, D. B.; Kapitulnik, A.

1989-11-01

Photoemission results from the Pr and La doped 1 2 3 system (Pr 0.2La 0.8) (Ba 1.875La 0.125)Cu 3O 7-gd are reported. The core level spectra show strong resemblance to those of other compounds of the 1 2 3 and 2 1 4 systems. The Cu 2 p satellite intensity is found to be ˜ 35% of the main Cu 2 p line, and the O 1 s core level spectra, exhibiting a clear doublet, show evidence of extrinsic oxygen. The clear correlation between the intensities of certain features in the valence band and the amount of extrinsic oxygen, as monitored by the O 1 s core level spectra, is explicitly addressed.

H2O2 Production in Species of the Lactobacillus acidophilus Group: a Central Role for a Novel NADH-Dependent Flavin Reductase

PubMed Central

Hertzberger, Rosanne; Arents, Jos; Dekker, Henk L.; Pridmore, R. David; Gysler, Christof; Kleerebezem, Michiel

2014-01-01

Hydrogen peroxide production is a well-known trait of many bacterial species associated with the human body. In the presence of oxygen, the probiotic lactic acid bacterium Lactobacillus johnsonii NCC 533 excretes up to 1 mM H2O2, inducing growth stagnation and cell death. Disruption of genes commonly assumed to be involved in H2O2 production (e.g., pyruvate oxidase, NADH oxidase, and lactate oxidase) did not affect this. Here we describe the purification of a novel NADH-dependent flavin reductase encoded by two highly similar genes (LJ_0548 and LJ_0549) that are conserved in lactobacilli belonging to the Lactobacillus acidophilus group. The genes are predicted to encode two 20-kDa proteins containing flavin mononucleotide (FMN) reductase conserved domains. Reductase activity requires FMN, flavin adenine dinucleotide (FAD), or riboflavin and is specific for NADH and not NADPH. The Km for FMN is 30 ± 8 μM, in accordance with its proposed in vivo role in H2O2 production. Deletion of the encoding genes in L. johnsonii led to a 40-fold reduction of hydrogen peroxide formation. H2O2 production in this mutant could only be restored by in trans complementation of both genes. Our work identifies a novel, conserved NADH-dependent flavin reductase that is prominently involved in H2O2 production in L. johnsonii. PMID:24487531

Comportamiento dinámico de asteroides en la resonancia 2:1

NASA Astrophysics Data System (ADS)

López García, F.; Brunini, A.

El propósito de este trabajo es mostrar los resultados obtenidos del estudio del movimiento de asteroides cercanos a la conmensurabilidad 2:1 con el movimiento medio de Júpiter, analizando el comportamiento de órbitas de asteroides reales y ficticios. Se analizan los tiempos de Lyapunov obtenidos a partir de la integración de las ecuaciones del movimiento. Se han estudiado la órbitas utilizando el modelo de cinco cuerpos y se han considerado los casos planar y espacial. Las simulaciones numéricas se realizaron utilizando integradores simpléticos y el intervalo de tiempo de integración fue de T = 107 años.

Immuno-detection of OCTN1 (SLC22A4) in HeLa cells and characterization of transport function.

PubMed

Pochini, Lorena; Scalise, Mariafrancesca; Indiveri, Cesare

2015-11-01

OCTN1 was immuno-detected in the cervical cancer cell HeLa, in which the complete pattern of acetylcholine metabolizing enzymes is expressed. Comparison of immuno-staining intensity of HeLa OCTN1 with the purified recombinant human OCTN1 allowed measuring the specific OCTN1 concentration in the HeLa cell extract and, hence calculating the HeLa OCTN1 specific transport activity that was about 10 nmol×min(-1)×mg protein(-1), measured as uptake of [(3)H]acetylcholine in proteoliposomes reconstituted with HeLa extract. This value was very similar to the specific activity of the recombinant protein. Acetylcholine transport was suppressed by incubation of the protein or proteoliposomes with the anti-OCTN1 antibody and was strongly inhibited by PLP and MTSEA, known inhibitors of OCTN1. The absence of ATP in the internal side of proteoliposomes strongly impaired transport function of both the HeLa and, as expected, the recombinant OCTN1. HeLa OCTN1 was inhibited by spermine, NaCl (Na(+)), TEA, γ-butyrobetaine, choline, acetylcarnitine and ipratropium but not by neostigmine. Besides acetylcholine, choline was taken up by HeLa OCTN1 proteoliposomes. The transporter catalyzed also acetylcholine and choline efflux which, differently from uptake, was not inhibited by MTSEA. Time course of [(3)H]acetylcholine uptake in intact HeLa cells was measured. As in proteoliposomes, acetylcholine transport in intact cells was inhibited by TEA and NaCl. Efflux of [(3)H]acetylcholine occurred in intact cells, as well. The experimental data concur in demonstrating a role of OCTN1 in transporting acetylcholine and choline in HeLa cells. Copyright © 2015 Elsevier B.V. All rights reserved.

Involvement of S6K1 in mitochondria function and structure in HeLa cells.

PubMed

Park, Jisoo; Tran, Quangdon; Mun, Kisun; Masuda, Kouhei; Kwon, So Hee; Kim, Seon-Hwan; Kim, Dong-Hoon; Thomas, George; Park, Jongsun

2016-12-01

The major biological function of mitochondria is to generate cellular energy through oxidative phosphorylation. Apart from cellular respiration, mitochondria also play a key role in signaling processes, including aging and cancer metabolism. It has been shown that S6K1-knockout mice are resistant to obesity due to enhanced beta-oxidation, with an increased number of large mitochondria. Therefore, in this report, the possible involvement of S6K1 in regulating mitochondria dynamics and function has been investigated in stable lenti-shS6K1-HeLa cells. Interestingly, S6K1-stably depleted HeLa cells showed phenotypical changes in mitochondria morphology. This observation was further confirmed by detailed image analysis of mitochondria shape. Corresponding molecular changes were also observed in these cells, such as the induction of mitochondrial fission proteins (Drp1 and Fis1). Oxygen consumption is elevated in S6K1-depeleted HeLa cells and FL5.12 cells. In addition, S6K1 depletion leads to enhancement of ATP production in cytoplasm and mitochondria. However, the relative ratio of mitochondrial ATP to cytoplasmic ATP is actually decreased in lenti-shS6K1-HeLa cells compared to control cells. Lastly, induction of mitophagy was found in lenti-shS6K1-HeLa cells with corresponding changes of mitochondria shape on electron microscope analysis. Taken together, our results indicate that S6K1 is involved in the regulation of mitochondria morphology and function in HeLa cells. This study will provide novel insights into S6K1 function in mitochondria-mediated cellular signaling. Copyright © 2016 Elsevier Inc. All rights reserved.

Diurnal variation in bacterioplankton composition and DNA damage in the microbial community from an Andean oligotrophic lake.

PubMed

Fernández-Zenoff, María V; Estévez, María C; Farías, María E

2014-01-01

Laguna Azul is an oligotrophic lake situated at 4,560 m above sea level and subject to a high level of solar radiation. Bacterioplankton community composition (BCC) was analysed by denaturing gradient gel electrophoresis and the impact of solar ultraviolet radiation was assessed by measuring cyclobutane pyrimidine dimers (CPD). Furthermore, pure cultures of Acinetobacter johnsonii A2 and Rhodococcus sp. A5 were exposed simultaneously and CPD accumulation was studied. Gel analyses generated a total of 7 sequences belonging to Alpha-proteobacteria (1 band), Beta-proteobacteria (1 band), Bacteroidetes (2 bands), Actinobacteria (1 band), and Firmicutes (1 band). DGGE profiles showed minimal changes in BCC and no CPD was detected even though a high level of damage was found in biodosimeters. A. johnsonii A2 showed low level of DNA damage while Rhodococcus sp. A5 exhibited high resistance since no CPD were detected under natural UV-B exposure, suggesting that the bacterial community is well adapted to this highly solar irradiated environment. Copyright © 2014 Asociación Argentina de Microbiología. Publicado por Elsevier España. All rights reserved.

Electrical conductivity and thermoelectric power of La1- x Li x CoO3-δ (0 ≤ x ≤ 0.1) oxides

NASA Astrophysics Data System (ADS)

Vecherskii, S. I.; Konopel'ko, M. A.; Batalov, N. N.; Antonov, B. D.; Reznitskikh, O. G.; Yaroslavtseva, T. V.

2016-12-01

The influence of the concentration of lithium ions on the phase composition, the electrical conductivity, and the thermoelectric power of La1- x Li x CoO3-δ (0 ≤ x ≤ 0.1) oxides synthesized by the ceramic method has been investigated. It has been found that the region of the existence of perovskite-type La1- x Li x CoO3-δ solid solutions does not exceed x = 0.05. The doping with lithium leads to an increase in the electrical conductivity of single-phase samples in comparison with that of the LaCoO3 compound. As the temperature increases from 300 to 400 K, the thermoelectric power of the LaCoO3 compound increases from the negative to positive values and then decreases, but remains positive in the temperature range from 400 to 1020 K. The thermoelectric power of the other samples has a positive sign. The results obtained have been discussed based on the models of the electron density of states in LaCoO3 and La1- x Sr x CoO3-δ, proposed in the studies of Señarís-Rodríguez and Goodenough, as well as in the framework of the theory of non-crystalline materials, developed by Mott.

The Influence of Layer Thickness-Ratio on Magnetoresistance in La2/3Ca1/3MnO3/La1/3Ca2/3MnO3 Exchange Biased System

NASA Astrophysics Data System (ADS)

Gomez, Maria Elena; Milena Diez, Sandra; Cuartas, Lina Maria; Marin, Lorena; Prieto, Pedro

2012-02-01

Isothermal magnetic field dependence of the resistance in La2/3Ca1/3MnO3 (F-LCMO)/ La1/3Ca2/3MnO3(AF-LCMO) bilayer and AF-LCMO/F-LCMO/AF-LCMO trilayer at temperatures below N'eel temperature of the antiferromagnetic layer were carried out to study the thickness layers influence on magneto transport properties. We grew multilayers using a high oxygen pressure sputtering technique. We systematically varied the thickness of the F-LCMO layer, tF, maintaining constant the thickness of the AF-LCMO layer, tAF. We studied the influence of the thickness ratio tF/tAF on the ZFC and FC magnetoresistance (MR) loops. HFC was varied from 100 Oe to 400 Oe. We found that MR has hysteretic behavior as observed in [La2/3Ca1/3MnO3/La1/3Ca2/3MnO3]N superlattices, where MR increases with the increasing field from H=0 to a maximum and then it decreases continuously. The position and magnitude of the maximum is not symmetric with respect to the axis H=0 for both FC and ZFC loops. We found that magnetoresistance behavior of the bilayer and trilayer is thickness-ratio dependent for both ZFC and FC loops.

Investigation of Thermal Conductivities and Expansion Coefficients of (Yb1 - x La x )2AlTaO7 Ceramics

NASA Astrophysics Data System (ADS)

Xiaoge, Chen; Hongsong, Zhang; Sai, Su; Yongde, Zhao; An, Tang; Haoming, Zhang

2017-12-01

The (Yb1 - x La x )2AlTaO7 ( x = 0, 0.1, 0.3, 0.5) ceramics were prepared by solid-state reaction method. The phase composition, microstructure, thermophysical properties of (Yb1 - x La x )2AlTaO7 ceramics were investigated. Results reveal that (Yb1 - x La x )2AlTaO7 ( x = 0, 0.1, 0.3) ceramics exhibit a single pyrochlore-type structure, and the (Yb0.5La0.5)2AlTaO7 has an orthorhombic weberite structure. The thermal conductivities of (Yb1 - x La x )2AlTaO7 ( x = 0, 0.1, 0.3) ceramics decrease with increasing Yb2O3 contents. (Yb0.5La0.5)2AlTaO7 has the highest thermal conductivity among all the ceramics studied, within the range of 1.48-1.75 W/m K (20-1200 °C). The thermal expansion coefficients of (Yb1 - x La x )2AlTaO7 ceramics decrease gradually with increasing La2O3 fractions, and the thermal expansion coefficients are close to those of YSZ.

Thermoelectric properties of LaRh(1-x)Ni(x)O(3).

PubMed

Shibasaki, S; Takahashi, Y; Terasaki, I

2009-03-18

We report measurements and analyses of resistivity, thermopower and thermal conductivity of polycrystalline samples of perovskite LaRh(1-x)Ni(x)O(3). The thermopower is found to be large at 800 K (185 µV K(-1) for x = 0.3), which is ascribed to the high-temperature stability of the low-spin state of Rh(3+)/Rh(4+) ions. This clearly contrasts with the thermopower of the isostructural oxide LaCoO(3), which rapidly decreases above 500 K owing to the spin-state transition. The spin state of the transition-metal ions is one of the most important parameters in oxide thermoelectrics.

La 139 NMR investigation of the charge and spin order in a La 1.885 Sr 0.115 CuO 4 single crystal

DOE PAGES

Arsenault, A.; Takahashi, S. K.; Imai, T.; ...

2018-02-14

139La NMR is suited for investigations into magnetic properties of La 2CuO 4 -based cuprates in the vicinity of their magnetic instabilities, owing to the modest hyperfine interactions between 139La nuclear spins and Cu electron spins. We report comprehensive 139La NMR measurements on a single-crystal sample of high-T c superconductor La 1.885 Sr 0.115 CuO 4 in a broad temperature range across the charge and spin order transitions (T charge ≃ 80 K, T neutron spin ≃ T c = 30 K). From the high-precision measurements of the linewidth for the nuclear spin I z = + 1 / 2 to -1/2 central transition, we show that paramagnetic line broadening sets in precisely at T charge due to enhanced spin correlations within the CuO 2 planes. Additional paramagnetic line broadening ensues below ~35 K, signaling that Cu spins in some segments of CuO 2 planes are on the verge of three-dimensional magnetic order. A static hyperfine magnetic field arising from ordered Cu moments along the ab plane, however, begins to develop only below Tmore » $$μSR\\atop{spin}$$ = 15 – 20 K, where earlier muon spin rotation measurements detected Larmor precession for a small volume fraction (~20 % ) of the sample. Based on the measurement of 139 La nuclear-spin-lattice relaxation rate 1/T 1, we also show that charge order triggers enhancement of low-frequency Cu spin fluctuations inhomogeneously; a growing fraction of 139 La sites is affected by enhanced low-frequency spin fluctuations toward the eventual magnetic order, whereas a diminishing fraction continues to exhibit a behavior analogous to the optimally superconducting phase even below T charge. In conclusion, these 139La NMR results corroborate our recent 63Cu NMR observation that a very broad, anomalous winglike signal gradually emerges below T charge, whereas the normally behaving, narrower main peak is gradually wiped out [T. Imai et al., Phys. Rev. B 96, 224508 (2017)]. Furthermore, we show that the enhancement of low-energy spin

La 139 NMR investigation of the charge and spin order in a La 1.885 Sr 0.115 CuO 4 single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arsenault, A.; Takahashi, S. K.; Imai, T.

139La NMR is suited for investigations into magnetic properties of La 2CuO 4 -based cuprates in the vicinity of their magnetic instabilities, owing to the modest hyperfine interactions between 139La nuclear spins and Cu electron spins. We report comprehensive 139La NMR measurements on a single-crystal sample of high-T c superconductor La 1.885 Sr 0.115 CuO 4 in a broad temperature range across the charge and spin order transitions (T charge ≃ 80 K, T neutron spin ≃ T c = 30 K). From the high-precision measurements of the linewidth for the nuclear spin I z = + 1 / 2 to -1/2 central transition, we show that paramagnetic line broadening sets in precisely at T charge due to enhanced spin correlations within the CuO 2 planes. Additional paramagnetic line broadening ensues below ~35 K, signaling that Cu spins in some segments of CuO 2 planes are on the verge of three-dimensional magnetic order. A static hyperfine magnetic field arising from ordered Cu moments along the ab plane, however, begins to develop only below Tmore » $$μSR\\atop{spin}$$ = 15 – 20 K, where earlier muon spin rotation measurements detected Larmor precession for a small volume fraction (~20 % ) of the sample. Based on the measurement of 139 La nuclear-spin-lattice relaxation rate 1/T 1, we also show that charge order triggers enhancement of low-frequency Cu spin fluctuations inhomogeneously; a growing fraction of 139 La sites is affected by enhanced low-frequency spin fluctuations toward the eventual magnetic order, whereas a diminishing fraction continues to exhibit a behavior analogous to the optimally superconducting phase even below T charge. In conclusion, these 139La NMR results corroborate our recent 63Cu NMR observation that a very broad, anomalous winglike signal gradually emerges below T charge, whereas the normally behaving, narrower main peak is gradually wiped out [T. Imai et al., Phys. Rev. B 96, 224508 (2017)]. Furthermore, we show that the enhancement of low-energy spin

Two-dimensional confinement of 3d{1} electrons in LaTiO_{3}/LaAlO{3} multilayers.

PubMed

Seo, S S A; Han, M J; Hassink, G W J; Choi, W S; Moon, S J; Kim, J S; Susaki, T; Lee, Y S; Yu, J; Bernhard, C; Hwang, H Y; Rijnders, G; Blank, D H A; Keimer, B; Noh, T W

2010-01-22

We report spectroscopic ellipsometry measurements of the anisotropy of the interband transitions parallel and perpendicular to the planes of (LaTiO3)n(LaAlO3)5 multilayers with n=1-3. These provide direct information about the electronic structure of the two-dimensional (2D) 3d{1} state of the Ti ions. In combination with local density approximation, including a Hubbard U calculation, we suggest that 2D confinement in the TiO2 slabs lifts the degeneracy of the t{2g} states leaving only the planar d{xy} orbitals occupied. We outline that these multilayers can serve as a model system for the study of the t{2g} 2D Hubbard model.

Radiosensitivity in HeLa cervical cancer cells overexpressing glutathione S-transferase π 1

PubMed Central

YANG, LIANG; LIU, REN; MA, HONG-BIN; YING, MING-ZHEN; WANG, YA-JIE

2015-01-01

The aims of the present study were to investigate the effect of overexpressed exogenous glutathione S-transferase π 1 (GSTP1) gene on the radiosensitivity of the HeLa human cervical cancer cell line and conduct a preliminarily investigation into the underlying mechanisms of the effect. The full-length sequence of human GSTP1 was obtained by performing a polymerase chain reaction (PCR) using primers based on the GenBank sequence of GSTP1. Subsequently, the gene was cloned into a recombinant eukaryotic expression plasmid, and the resulting construct was confirmed by restriction analysis and DNA sequencing. A HeLa cell line that was stably expressing high levels of GSTP1 was obtained through stable transfection of the constructed plasmids using lipofectamine and screening for G418 resistance, as demonstrated by reverse transcription-PCR. Using the transfected HeLa cells, a colony formation assay was conducted to detect the influence of GSTP1 overexpression on the cell radiosensitivity. Furthermore, flow cytometry was used to investigate the effect of GSTP1 overexpression on cell cycle progression, with the protein expression levels of the cell cycle regulating factor cyclin B1 detected using western blot analysis. Colony formation and G2/M phase arrest in the GSTP1-expressing cells were significantly increased compared with the control group (P<0.01). In addition, the expression of cyclin B1 was significantly reduced in the GSTP1-expressing cells. These results demonstrated that increased expression of GSTP1 inhibits radiosensitivity in HeLa cells. The mechanism underlying this effect may be associated with the ability of the GSTP1 protein to reduce cyclin B1 expression, resulting in significant G2/M phase arrest. PMID:26622693

Radiosensitivity in HeLa cervical cancer cells overexpressing glutathione S-transferase π 1.

PubMed

Yang, Liang; Liu, Ren; Ma, Hong-Bin; Ying, Ming-Zhen; Wang, Ya-Jie

2015-09-01

The aims of the present study were to investigate the effect of overexpressed exogenous glutathione S-transferase π 1 ( GSTP1 ) gene on the radiosensitivity of the HeLa human cervical cancer cell line and conduct a preliminarily investigation into the underlying mechanisms of the effect. The full-length sequence of human GSTP1 was obtained by performing a polymerase chain reaction (PCR) using primers based on the GenBank sequence of GSTP1. Subsequently, the gene was cloned into a recombinant eukaryotic expression plasmid, and the resulting construct was confirmed by restriction analysis and DNA sequencing. A HeLa cell line that was stably expressing high levels of GSTP1 was obtained through stable transfection of the constructed plasmids using lipofectamine and screening for G418 resistance, as demonstrated by reverse transcription-PCR. Using the transfected HeLa cells, a colony formation assay was conducted to detect the influence of GSTP1 overexpression on the cell radiosensitivity. Furthermore, flow cytometry was used to investigate the effect of GSTP1 overexpression on cell cycle progression, with the protein expression levels of the cell cycle regulating factor cyclin B1 detected using western blot analysis. Colony formation and G 2 /M phase arrest in the GSTP1 -expressing cells were significantly increased compared with the control group (P<0.01). In addition, the expression of cyclin B1 was significantly reduced in the GSTP1 -expressing cells. These results demonstrated that increased expression of GSTP1 inhibits radiosensitivity in HeLa cells. The mechanism underlying this effect may be associated with the ability of the GSTP1 protein to reduce cyclin B1 expression, resulting in significant G 2 /M phase arrest.

Thermal expansion and specific heat of La1-xTexCoO3

NASA Astrophysics Data System (ADS)

Thakur, Rasna; Thakur, Rajesh K.; Gaur, N. K.

2018-05-01

We present the specific heat and thermal expansion of La1-xTexCoO3 family using Modified Rigid Ion Model (MRIM). The effect of Te doping on the thermal and cohesive properties have been studied by an atomistic approach. The Debye temperature of these perovskite materials is also predicted. The effect of Tellurium doping on lattice specific heat (C), thermal expansion (α) of La1-xTexCoO3 (x= 0.05-0.25) as a function of temperature (1K≤T≤1000K) is reported probably for the first time.

Proteomic Characterization of Plasmid pLA1 for Biodegradation of Polycyclic Aromatic Hydrocarbons in the Marine Bacterium, Novosphingobium pentaromativorans US6-1

PubMed Central

Yun, Sung Ho; Choi, Chi-Won; Lee, Sang-Yeop; Lee, Yeol Gyun; Kwon, Joseph; Leem, Sun Hee; Chung, Young Ho; Kahng, Hyung-Yeel; Kim, Sang Jin; Kwon, Kae Kyoung; Kim, Seung Il

2014-01-01

Novosphingobium pentaromativorans US6-1 is a halophilic marine bacterium able to degrade polycyclic aromatic hydrocarbons (PAHs). Genome sequence analysis revealed that the large plasmid pLA1 present in N. pentaromativorans US6-1 consists of 199 ORFs and possess putative biodegradation genes that may be involved in PAH degradation. 1-DE/LC-MS/MS analysis of N. pentaromativorans US6-1 cultured in the presence of different PAHs and monocyclic aromatic hydrocarbons (MAHs) identified approximately 1,000 and 1,400 proteins, respectively. Up-regulated biodegradation enzymes, including those belonging to pLA1, were quantitatively compared. Among the PAHs, phenanthrene induced the strongest up-regulation of extradiol cleavage pathway enzymes such as ring-hydroxylating dioxygenase, putative biphenyl-2,3-diol 1,2-dioxygenase, and catechol 2,3-dioxygenase in pLA1. These enzymes lead the initial step of the lower catabolic pathway of aromatic hydrocarbons through the extradiol cleavage pathway and participate in the attack of PAH ring cleavage, respectively. However, N. pentaromativorans US6-1 cultured with p-hydroxybenzoate induced activation of another extradiol cleavage pathway, the protocatechuate 4,5-dioxygenase pathway, that originated from chromosomal genes. These results suggest that N. pentaromativorans US6-1 utilizes two different extradiol pathways and plasmid pLA1 might play a key role in the biodegradation of PAH in N. pentaromativorans US6-1. PMID:24608660

Observation of divergent La{sup 3+} ion dilute effect in two series of 3-D fluorescent lanthanide-MOFs-based molecular alloys RE{sub x}La{sub 1−x}–EBTC (RE{sup 3+}=Eu{sup 3+} or Tb{sup 3+}; EBTC{sup 4−}=1,1′-ethynebenzene-3,3′,5,5′-etracarboxylate)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Lu; State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093; Zhang, Wen-Wei, E-mail: wwzhang@nju.edu.cn

The lanthanide metal-organic frameworks (MOFs) [Ln{sub 2}(EBTC){sub 1.5}(CH{sub 3}OH){sub 4}]·6H{sub 2}O are isostructural to each other, where EBTC{sup 4−}=1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate; Ln{sup 3+}=La{sup 3+}, Eu{sup 3+} and Tb{sup 3+}; and the corresponding MOF is abbreviated as Ln–EBTC. MOFs Eu–EBTC and Tb–EBTC emit intense red and green luminescence (visible by bare eyes), respectively. The molecular alloys of Eu{sub x}La{sub 1−x}–EBTC and Tb{sub x}La{sub 1−x}–EBTC have been successfully prepared by mixing Eu{sup 3+}/Tb{sup 3+} and La{sup 3+} salts with the desired molar ratio in the starting material. Two series of Eu{sub x}La{sub 1−x}–EBTC and Tb{sub x}La{sub 1−x}–EBTC molecular alloys are isomorphic to the parentmore » Ln–EBTC MOFs, while exhibit divergent La{sup 3+} ion diluting effect, namely, with increasing the relative amount of La{sup 3+}, the intensity of characteristic emission arising from Tb{sup 3+} ion monotonely increases in Tb{sub x}La{sub 1−x}–EBTC molecular alloys, whereas that of Eu{sup 3+} ion shows non-monotone decrease in Eu{sub x}La{sub 1−x}–EBTC molecular alloys. The possible origin is discussed for such a divergent behavior between Eu{sub x}La{sub 1−x}–EBTC and Tb{sub x}La{sub 1−x}–EBTC molecular alloys. - Graphical abstract: Two series of 3-D fluorescent lanthanide-MOFs-based molecular alloys RE{sub x}La{sub 1−x}–EBTC (RE{sup 3+}=Eu{sup 3+} or Tb{sup 3+}; EBTC{sup 4−}=1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate) have been successfully prepared by mixing Eu{sup 3+}/Tb{sup 3+} and La{sup 3+} salts with the desired molar ratio in the starting material and showed photoluminescence property with divergent La{sup 3+} ion dilute effect. - Highlights: • 3-D molecular alloys of Eu{sub x}La{sub 1−x}–EBTC and Tb{sub x}La{sub 1−x}–EBTC were prepared. • They are isomorphic to the parent Ln–EBTC MOFs. • They show photoluminescence property with divergent

[miR-497 suppresses proliferation of human cervical carcinoma HeLa cells by targeting cyclin E1].

PubMed

Han, Jiming; Huo, Manpeng; Mu, Mingtao; Liu, Junjun; Zhang, Jing

2014-06-01

To evaluate the effect of miR-497 on proliferation of human cervical carcinoma HeLa cells and target relationship between miR-497 and cyclin E1 (CCNE1). Pre-miR-497 sequences were synthesized and cloned into pcDNATM6.2-GW to construct recombinant plasmid pcDNATM6.2-GW-pre-miR-497 and identified by real-time quantitative PCR (qRT-PCR). In addition, sequences of the wild-type CCNE1 (WT-CCNE1) and mutant CCNE1 (MT-CCNE1) were respectively cloned into pmirGLO vectors. MTT assay was used to explore the impact of miR-497 on the proliferation of HeLa cells. Furthermore, the target effect of miR-497 on the CCNE1 was identified by dual-luciferase reporter assay system, qRT-PCR and Western blotting. The recombinant plasmids pcDNATM6.2-GW-pre-miR-497 and pmirGLO-WT-CCNE1, pmirGLO-MT-CCNE1 were successfully constructed, and the miR-497 expression level in HeLa cells transfected with pre-miR-497 was significantly higher than that in the neg-miR group (P<0.05). MTT assay showed that miR-497 could significantly inhibit the proliferation of HeLa cells (P<0.05). A remarkable reduction of luciferase activities of WT-CCNE1 reporter was observed in HeLa cells with pre-miR-497 transfection (P<0.01), and the mRNA and protein expression levels of CCNE1 were down-regulated in HeLa cells transfected with pre-miR-497 (P<0.05). Over-expressed miR-497 in HeLa cells could suppress cell proliferation by targeting CCNE1.

Metal ion displacements in noncentrosymmetric chalcogenides La3Ga1.67S7, La3Ag0.6GaCh7 (Ch=S, Se), and La3MGaSe7 (M=Zn, Cd)

NASA Astrophysics Data System (ADS)

Iyer, Abishek K.; Yin, Wenlong; Rudyk, Brent W.; Lin, Xinsong; Nilges, Tom; Mar, Arthur

2016-11-01

The quaternary Ga-containing chalcogenides La3Ag0.6GaS7, La3Ag0.6GaSe7, La3ZnGaSe7, and La3CdGaSe7, as well as the related ternary chalcogenide La3Ga1.67S7, were prepared by reactions of the elements at 950 °C. They adopt noncentrosymmetric hexagonal structures (space group P63, Z=2) with cell parameters (a=10.2 Å, c=6.1 Å for the sulfides; a=10.6 Å, c=6.4 Å for the selenides) that are largely controlled by the geometrical requirements of one-dimensional stacks of Ga-centered tetrahedra separated by the La atoms. Among these compounds, which share the common formulation La3M1-xGaCh7 (M=Ga, Ag, Zn, Cd; Ch=S, Se), the M atoms occupy sites within a stacking of trigonal antiprisms formed by Ch atoms. The location of the M site varies between extremes with trigonal antiprismatic (CN6) and trigonal planar (CN3) geometry. Partial occupation of these sites and intermediate ones accounts for the considerable versatility of these structures and the occurrence of large metal displacement parameters. The site occupations can be understood in a simple way as being driven by the need to satisfy appropriate bond valence sums for both the M and Ch atoms. Band structure calculations rationalize the substoichiometry observed in the Ag-containing compounds (La3Ag0.6GaS7, La3Ag0.6GaSe7) as a response to overbonding. X-ray photoelectron spectroscopy supports the presence of monovalent Ag atoms in these compounds, which are not charge-balanced.

Loss of Selenium-Binding Protein 1 Decreases Sensitivity to Clastogens and Intracellular Selenium Content in HeLa Cells.

PubMed

Zhao, Changhui; Zeng, Huawei; Wu, Ryan T Y; Cheng, Wen-Hsing

2016-01-01

Selenium-binding protein 1 (SBP1) is not a selenoprotein but structurally binds selenium. Loss of SBP1 during carcinogenesis usually predicts poor prognosis. Because genome instability is a hallmark of cancer, we hypothesize that SBP1 sequesters cellular selenium and sensitizes cancer cells to DNA-damaging agents. To test this hypothesis, we knocked down SBP1 expression in HeLa cervical cancer cells by employing a short hairpin RNA (shRNA) approach. Reduced sensitivity to hydrogen peroxide, paraquat and camptothecin, reactive oxygen species content, and intracellular retention of selenium after selenomethionine treatment were observed in SBP1 shRNA HeLa cells. Results from Western analyses showed that treatment of HeLa cells with selenomethionine resulted in increased SBP1 protein expression in a dose-dependent manner. Knockdown of SBP1 rendered HeLa cells increased expression of glutathione peroxidase-1 but not glutathione peroxidase-4 protein levels and accelerated migration from a wound. Altogether, SBP1 retains supplemental selenium and sensitizes HeLa cancer cells to clastogens, suggesting a new cancer treatment strategy by sequestering selenium through SBP1.

Magnetic field induced anisotropy of 139La spin-lattice relaxation rates in stripe ordered La 1.875Ba 0.125CuO 4

DOE PAGES

S. -H. Baek; Gu, G. D.; Utz, Y.; ...

2015-10-26

We report 139La nuclear magnetic resonance studies performed on a La 1.875Ba 0.125CuO 4 single crystal. The data show that the structural phase transitions (high-temperature tetragonal → low-temperature orthorhombic → low-temperature tetragonal phase) are of the displacive type in this material. The 139La spin-lattice relaxation rate T –1 1 sharply upturns at the charge-ordering temperature T CO = 54 K, indicating that charge order triggers the slowing down of spin fluctuations. Detailed temperature and field dependencies of the T –1 1 below the spin-ordering temperature T SO=40 K reveal the development of enhanced spin fluctuations in the spin-ordered state formore » H ∥ [001], which are completely suppressed for large fields along the CuO 2 planes. Lastly, our results shed light on the unusual spin fluctuations in the charge and spin stripe ordered lanthanum cuprates.« less

Magnetic field induced anisotropy of 139La spin-lattice relaxation rates in stripe ordered La 1.875Ba 0.125CuO 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

S. -H. Baek; Gu, G. D.; Utz, Y.

We report 139La nuclear magnetic resonance studies performed on a La 1.875Ba 0.125CuO 4 single crystal. The data show that the structural phase transitions (high-temperature tetragonal → low-temperature orthorhombic → low-temperature tetragonal phase) are of the displacive type in this material. The 139La spin-lattice relaxation rate T –1 1 sharply upturns at the charge-ordering temperature T CO = 54 K, indicating that charge order triggers the slowing down of spin fluctuations. Detailed temperature and field dependencies of the T –1 1 below the spin-ordering temperature T SO=40 K reveal the development of enhanced spin fluctuations in the spin-ordered state formore » H ∥ [001], which are completely suppressed for large fields along the CuO 2 planes. Lastly, our results shed light on the unusual spin fluctuations in the charge and spin stripe ordered lanthanum cuprates.« less

Perovskite-Type Oxides. I. Structural, Magnetic, and Morphological Properties of LaMn 1- xCu xO 3 and LaCo 1- xCu xO 3 Solid Solutions with Large Surface Area

NASA Astrophysics Data System (ADS)

Porta, Piero; De Rossi, Sergio; Faticanti, Marco; Minelli, Giuliano; Pettiti, Ida; Lisi, Luciana; Turco, Maria

1999-09-01

Perovskite-type compounds of general formula LaMn1-xCuxO3 and LaCo1-xCuxO3 (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by calcining the citrate gel precursors at 823, 923, and 1073 K. The decomposition of the precursors was followed by thermal analysis and the oxides were investigated by means of elemental analysis (atomic absorption and redox titration), X-ray powder diffraction, BET surface area, X-ray absorption (EXAFS and XANES), electron microscopy (SEM and TEM), and magnetic susceptibility. LaMn1-xCuxO3 samples are perovskite-like single phases up to x=0.6. At x=0.8 CuO and La2CuO4 phases are present in addition to perovskite. For x=1.0 the material is formed by CuO and La2CuO4. Mn(IV) was found by redox titration in all Mn-based perovskite samples, its fraction increasing with the increase in copper content. EXAFS and XANES analyses confirmed the presence of Mn(IV). Cation vacancies in equal amounts in the 12-coordinated A and octahedral B sites are suggested in the samples with x=0.0 and x=0.2, while for x=0.6 anionic vacancies are present. Materials with sufficiently high surface area (22-36 m2 g-1 for samples fired at 923 K and 14-22 m2 g-1 for those fired at 1073 K) were obtained. Crystallite sizes in the ranges 390-500 and 590-940 Å for samples calcined at 923 and 1073 K, respectively, were determined from the FWHM of the (102) X-ray diffraction peak. TEM patterns of LaMnO3 showed almost regular hexagonal prismatic crystals with sizes of the same order of magnitude (800 Å) of those drawn from X-ray diffraction, while no evidence of defect clustering was drawn out from TEM and electron diffraction images. For the sample with x=0.6, TEM and electron diffraction patterns revealed perturbation of the structure. Magnetic susceptibility studies show a ferromagnetic behavior that decreases with increase in x. LaCo1-xCuxO3 samples are perovskite-like single phases up to x=0.2. For x=0.4 a small amount of La2CuO4, in addition to perovskite, is detected. For

[Baicalein promotes the apoptosis of HeLa cells by inhibiting ERK1/2 expression].

PubMed

Wang, Yongzhou; Xia, Jiyi; Tang, Xiaoping; Tang, Li; Mao, Xiguang; Zhang, Yujiao; Yu, Xiaolan

2016-11-01

Objective To investigate the effects of baicalein and U0126 treatment on the apoptosis of human cervical carcinoma HeLa cells and the potential mechanism. Methods HeLa cells were subjected to (1, 2, 5, 10, 20, 50, 100, 200, 300) μmol/L baicalein or (1, 2, 5, 10, 20, 30) μmol/L U0126 treatment for 24 hours. The optimal concentrations of baicalein and U0126 for HeLa inhibition was determined by a cell counting Kit-8 assay. HeLa cells were then treated with these inhibitory concentrations for 24 hours separately or in combination. The cell cycle and the degree of apoptosis were analyzed by flow cytometry. The cell apoptosis index was evaluated by the TUNEL assay. The expressions of extracellular signal-regulated kinase 1/2 (ERK1/2), Bax, and Bcl-2 at the mRNA and protein levels were examined by real-time PCR and Western blotting, respectively. Results Optimal inhibitory concentrations of baicalein and U0126 for HeLa cells were 200 μmol/L and 10 μmol/L, respectively. Compared with the control group, baicalein treatment increased the growth rate of cells in the G0/G1 phase but decreased the S phase. Combination treatment of 200 μmol/L baicalein and 10 μmol/L U0126 for 24 hours further reduced the S phase growth rate. Treatment with 10 μmol/L U0126 or 200 μmol/L baicalein for 24 hours induced cell apoptosis, and the combination treatment induced more apoptosis. Treatment by baicalein alone or in combination with U0126 for 24 hours significantly decreased ERK1/2 and Bcl-2 mRNA expressions, and upregulated Bax mRNA expression. It also downregulated ERK1/2 phosphorylation and Bcl-2 protein expression, while increasing Bax protein expression. Conclusion Both baicalein and U012 appear to inhibit proliferation, induce apoptosis, and increase the growth rate in the G0/G1 phase but reduce the S phase of HeLa cells. This effect is enhanced when they are used synergistically.

Thermopower of CexR1-xB6 (R=La, Pr and Nd)

NASA Astrophysics Data System (ADS)

Kim, Moo‑Sung; Nakai, Yuki; Tou, Hideki; Sera, Masafumi; Iga, Fumitoshi; Takabatake, Toshiro; Kunii, Satoru

2006-06-01

The thermopower, S, of CexR1-xB6 (R=La, Pr, Nd) was investigated. S with a positive sign shows a typical behavior observed in the Ce Kondo system, an increase with decreasing temperature at high temperatures and a maximum at low temperatures. The S values of all the systems at high temperatures are roughly linearly dependent on the Ce concentration, indicating the conservation of the single-impurity character of the Kondo effect in a wide x range. However, the maximum value of S, Smax, and the temperature, Tmax, at which Smax is observed exhibit different x dependences between CexLa1-xB6 and CexR1-xB6 (R=Pr, Nd). In CexLa1-xB6, Tmax, which is ˜8 K in CeB6, decreases with decreasing x and converges to ˜1 K in a very dilute alloy and Smax shows an increase below x ˜ 0.1 after decreasing with decreasing x. In CexR1-xB6 (R=Pr, Nd), Tmax shows a weak x dependence but Smax shows a roughly linear decrease in x. These results are discussed from the standpoint of the chemical pressure effect and the Ce-Ce interaction. S in the long-range ordered phase shows very different behaviors between CexPr1-xB6 and CexNd1-xB6.

Short-range order in the Ca sub 1-x La sub x F sub 2+x solid solution: 1:0:3 or 1:0:4 clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laval, J.P.; Abaouz, A.; Frit, B.

1989-08-01

The defect structure of the Ca{sub 1-x}La{sub x}F{sub 2+x} solid solution (0 {le} x {le} 0.38) has been examined at room temperature by powder neutron diffraction. Two kinds of (xxx) interstitial anions, whose respective numbers increase linearly with increasing dopant cation concentration, have been found: one labeled F{sup 0} (x {approx} 0.41) is a true interstitial; the other labeled F{sup {prime}{double prime}} (x {approx} 0.31) can be considered a relaxed normal anion. Two 1:0:n defect clusters are compatible, within the experimental errors, with these results: the 1:0:3 (1V{sub F}, OF{prime}, 3F{sup {double prime}}, 2 La{sup 3+}) and the 1:0:4 (1V{submore » F}, OF{prime}, 4F{sup {double prime}}, 3La{sup 3+}) clusters. Charge balance considerations and comparisons with the homologous Ca{sub 1-x}M{sub x}{sup IV}F{sub 2+2x} solid solutions (M{sup IV} = Th, U) allow us to think that the less dense 1:0:3 cluster is present for the whole domain of both kinds of solid solutions.« less

Structural and dielectric characteristics of double perovskite La2(NiFe)1/2MnO6

NASA Astrophysics Data System (ADS)

Nasir, Mohd.; Kandasami, Asokan; Sen, Somaditya

2018-05-01

Recently, La2NiMnO6 has drawn significant interest because large magnetic field induced changes in dielectric properties makes this compound a promising material for potential spintronic device applications. In the present study, the structural and dielectric characteristics of sol-gel prepared La2(Ni1/2Fe1/2)MnO6 double perovskite ceramics were evaluated. La2(Ni1/2Fe1/2)MnO6 was crystallized in the monoclinic P21/n structure with ordered Ni2+/Fe2+ and Mn4+ cations. A giant dielectric constant with relaxor-like behavior was observed, which was attributed to the dipolar effects arising from hopping between Ni2+/Fe2+ and Mn4+ ions.

High-Temperature Thermoelectric Properties of (1 - x) SrTiO3 - ( x) La1/3NbO3 Ceramic Solid Solution

NASA Astrophysics Data System (ADS)

Srivastava, Deepanshu; Azough, F.; Molinari, M.; Parker, S. C.; Freer, R.

2015-06-01

Ceramics based on SrTiO3 are of growing interest as thermoelectric materials because of their high-temperature stability and non-toxicity. Substitution of La and Nb into the perovskite structure provides opportunities to control both the microstructure and properties. Ceramic solid solutions of (1 - x) SrTiO3 - ( x) La1/3NbO3 were prepared by the mixed oxide route, using compositional steps of x = 0.1. Pressed pellets were sintered at temperatures of 1573 K to 1723 K in air. Addition of aliovalent ions (La3+, Nb5+) on the A/B sites (Sr2+, Ti4+) led to A-Site cation deficiency in the stoichiometric compositions and other defect structures which increased carrier concentration. A maximum ZT of 0.004 was obtained for the x = 0.2 stoichiometric sample, although much higher ZT values are possible by sample reduction.

A Raman scattering study of the structural ordering in Bi1- x La x FeO3 ceramic ferroelectromagnetics

NASA Astrophysics Data System (ADS)

Teplyakova, N. A.; Titov, S. V.; Verbenko, I. A.; Sidorov, N. V.; Reznichenko, L. A.

2015-09-01

Based on Raman spectra, we have studied structural ordering processes in ceramics of ferroelectromagnetics Bi1- x La x FeO3 ( x = 0.075-0.20). It has been found that the structure of Bi1- x La x FeO3 is close to the structure of the crystal BiFeO3. However, lines in Raman spectra of Bi1- x La x FeO3 are considerably broadened compared to lines in the Raman spectrum of the BiFeO3 single crystal, which indicates that the structure of solid solutions is much more disordered. In Raman spectra of Bi1- x La x FeO3, in the range of librational vibrations of octahedra as a whole (50-90 cm-1), several groups of lines are observed in frequency ranges 59-69, 72-77, and 86-92 cm-1 (depending on the composition of solid solution). This confirms X-ray data that examined solid solutions are not single-phase. At a La content x = 0.120, Raman lines in the low-frequency spectral range narrow, which indicates that the ordering of structural units in cationic sublattices somewhat increases. Upon an increase in the content of La in the Bi1- x La x FeO3 structure, no unambiguous dependence of parameters of spectral lines is observed. It is likely that this is explained by the fact that, as the value of x increases, the character of the incorporation of La into the structure of the solid solution changes.

Electronic transition in La1-xSrxTiO3

NASA Astrophysics Data System (ADS)

Hays, C. C.; Zhou, J.-S.; Markert, J. T.; Goodenough, J. B.

1999-10-01

The transition with increasing x in La1-xSrxTiO3 from an antiferromagnetic, p-type polaronic conductor to an n-type metal with an enhanced Pauli paramagnetism was investigated by monitoring changes in structure, magnetic properties, and, under different hydrostatic pressures, the resistance and thermoelectric power of ceramic samples. We conclude that LaTiO3 is an itinerant-electron antiferromagnet and the transition is first order with a phase separation associated with cooperative oxygen-atom displacements that segregate strongly correlated states from Fermi-liquid states. The Néel temperature TN~145 K decreases precipitously to 100 K at the phase limit x=0.045+/-0.005 the two-phase domain extends over the compositions 0.045<=x<=0.08.

Paclitaxel-resistant HeLa cells have up-regulated levels of reactive oxygen species and increased expression of taxol resistance gene 1.

PubMed

Bi, Wenxiang; Wang, Yuxia; Sun, Gaoying; Zhang, Xiaojin; Wei, Yongqing; Li, Lu; Wang, Xiaoyuan

2014-07-01

This study is to establish a paclitaxel (PTX)-resistant human cervical carcinoma HeLa cell line (HeLa/PTX) and to investigate its redox characteristics and the expression of taxol resistance gene 1 (Txr1). HeLa cells were treated with PTX and effects of PTX on cell proliferation were detected through cell counting and the MTT assay. Levels of cellular reactive oxygen species (ROS), reduced glutathione (GSH), and oxidized glutathione (GSSG) as well as the ratio of GSH to GSSG were measured by the 2,7-difluorescein diacetate (DCFH-DA) method and the 5,5'dithiobis(2-nitrobenzoic acid) (DTNB) method. Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were determined by the nitrite formation method, the molybdate colorimetric method, and the DTNB colorimetric method, respectively. The level of Txr1 mRNA was determined by real-time PCR. Compared with the regular HeLa cells, HeLa/PTX cells were larger in size and had more cytoplasmic granules. The population doubling time for HeLa/PTX cells was 1.32 times of that of HeLa cells (P<0.01). HeLa/PTX cells showed stronger resistance to PTX than HeLa cells with a resistance index of 122.69. HeLa/PTX cells had higher levels of ROS (P<0.01) and Txr1 mRNA (P<0.01), lower level of GSH (P < 0.05), and lower activities of SOD (P<0.01) and GPx (P < 0.05) than HeLa cells. HeLa/PTX cells, with higher levels of ROS and Txr1 mRNA expression, are more resistant to PTX than HeLa cells.

The groESL Chaperone Operon of Lactobacillus johnsonii†

PubMed Central

Walker, D. Carey; Girgis, Hany S.; Klaenhammer, Todd R.

1999-01-01

The Lactobacillus johnsonii VPI 11088 groESL operon was localized on the chromosome near the insertion element IS1223. The operon was initially cloned as a series of three overlapping PCR fragments, which were sequenced and used to design primers to amplify the entire operon. The amplified fragment was used as a probe to recover the chromosomal copy of the groESL operon from a partial library of L. johnsonii VPI 11088 (NCK88) DNA, cloned in the shuttle vector pTRKH2. The 2,253-bp groESL fragment contained three putative open reading frames, two of which encoded the ubiquitous GroES and GroEL chaperone proteins. Analysis of the groESL promoter region revealed three transcription initiation sites, as well as three sets of inverted repeats (IR) positioned between the transcription and translation start sites. Two of the three IR sets bore significant homology to the CIRCE elements, implicated in negative regulation of the heat shock response in many bacteria. Northern analysis and primer extension revealed that multiple temperature-sensitive promoters preceded the groESL chaperone operon, suggesting that stress protein production in L. johnsonii is strongly regulated. Maximum groESL transcription activity was observed following a shift to 55°C, and a 15 to 30-min exposure of log-phase cells to this temperature increased the recovery of freeze-thawed L. johnsonii VPI 11088. These results suggest that a brief, preconditioning heat shock can be used to trigger increased chaperone production and provide significant cross-protection from the stresses imposed during the production of frozen culture concentrates. PMID:10388700

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Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-24

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Potential energy surfaces of LaH + and LaH + 2

NASA Astrophysics Data System (ADS)

Das, Kalyan K.; Balasubramanian, K.

1991-03-01

Using the complete active space multiconfiguration self-consistent field (CAS-MCSCF) followed by full second-order configuration interaction (SOCI) calculations, 16 electronic states of LaH+ and 8 electronic states of LaH+2 are investigated. The potential energy surface of these electronic states of LaH+2 and LaH+ are computed. These calculations show that the 3F(5d2) ground state of La+ ion forms a weak complex with H2. The La+(1D) excited state inserts into H2 with a small barrier (<8 kcal/mol) to form the 1A1 ground state of LaH+2 (re=2.057 Å, θe=106°). At the SOCI level of theory LaH+2 is found to be 11 kcal/mol more stable than La+(3F)+H2. Our calculations explain the experimental observations on La++H2→LaH++H reaction. The adiabatic ionization potential (IP) of LaH2 and LaH are calculated as 5.23 and 5.33 eV, respectively. The ground state of LaH+ was found to be a 2Δ state. We compute De(LaH+) and De(HLa-H+) as 2.54 eV in excellent agreement with the experimental De(LaH+)=2.57 eV measured by Armentrout and co-workers. The spin-orbit effects of LaH+ were also studied using the relativistic configuration interaction (RCI) method.

Structure and Differentiated Electrical Characteristics of M1/2La1/2Cu3Ti4O12 (M = Li, Na, K) Ceramics Prepared by Sol-Gel Method

NASA Astrophysics Data System (ADS)

Liu, Zhanqing; Yang, Zupei

2017-10-01

New M1/2La1/2Cu3Ti4O12 (M = Li, Na, K) ceramics based on partial substitution of Li+, Na+, and K+ for La3+ in La2/3Cu3Ti4O12 (LCTO) have been prepared by a sol-gel method, and the effects of Li+, Na+, and K+ on the microstructure and electrical properties investigated in detail, revealing different results depending on the substituent. The cell parameter increased with increasing radius of the substituent ion (Li+, Na+, K+). Li1/2La1/2Cu3Ti4O12 (LLCTO) ceramic showed better frequency and temperature stability, but the dielectric constant decreased and the third abnormal dielectric peak disappeared from the dielectric temperature spectrum. Na1/2La1/2Cu3Ti4O12 (NLCTO) ceramic exhibited higher dielectric constant and better frequency and temperature stability, and displayed the second dielectric relaxation in electric modulus plots. The performance of K1/2La1/2Cu3Ti4O12 (KLCTO) ceramic was deteriorated. These different microstructures and electrical properties may be due to the effect of different defect structures generated in the ceramic as well as grain size. This work represents the first analysis and comparison of these remarkable differences in the electrical behavior of ceramics obtained by partial substitution of Li+, Na+, and K+ for La3+ in LCTO.

Knockdown of HIP1 expression promotes ligand‑induced endocytosis of EGFR in HeLa cells.

PubMed

Li, Dan; Chen, Fenglin; Ding, Jian; Lin, Na; Li, Zonghai; Wang, Xiaozhong

2017-12-01

Huntington-interacting protein 1 (HIP1) is associated with various tumor types; however, its precise functions in tumor cells are unclear. In this study, the effects of HIP1 on the degradation of EGFR, which have important roles in carcinogenesis after EGF stimulation, were examined. After screening 17 cell lines, the coexpression of HIP1 and EGFR was detected in HeLa cells. Accordingly, the expression of HIP1 was knocked down in HeLa cells using various HIP1 siRNA sequences. The endocytosis of EGFR and localization of clathrin in HeLa cells were examined after stimulation by EGF at various concentrations (i.e., 1.5 and 100 ng/ml). After HIP1 expression was blocked by siRNAs, EGFR endocytosis was accelerated and this effect was dependent on the EGF concentration. This endocytosis was colocalized with clathrin expression. These findings indicate that the inhibition of HIP1 can accelerate the endocytosis and degradation of EGFR. Furthermore, they suggest that HIP1 is a potential therapeutic target for various cancer types, particularly those with high EGFR expression, but further research is needed to examine this hypothesis.

Knockdown of HIP1 expression promotes ligand-induced endocytosis of EGFR in HeLa cells

PubMed Central

Li, Dan; Chen, Fenglin; Ding, Jian; Lin, Na; Li, Zonghai; Wang, Xiaozhong

2017-01-01

Huntington-interacting protein 1 (HIP1) is associated with various tumor types; however, its precise functions in tumor cells are unclear. In this study, the effects of HIP1 on the degradation of EGFR, which have important roles in carcinogenesis after EGF stimulation, were examined. After screening 17 cell lines, the coexpression of HIP1 and EGFR was detected in HeLa cells. Accordingly, the expression of HIP1 was knocked down in HeLa cells using various HIP1 siRNA sequences. The endocytosis of EGFR and localization of clathrin in HeLa cells were examined after stimulation by EGF at various concentrations (i.e., 1.5 and 100 ng/ml). After HIP1 expression was blocked by siRNAs, EGFR endocytosis was accelerated and this effect was dependent on the EGF concentration. This endocytosis was colocalized with clathrin expression. These findings indicate that the inhibition of HIP1 can accelerate the endocytosis and degradation of EGFR. Furthermore, they suggest that HIP1 is a potential therapeutic target for various cancer types, particularly those with high EGFR expression, but further research is needed to examine this hypothesis. PMID:29039605

Transition from the diamagnetic insulator to ferromagnetic metal in La1-xSrxCoO3

NASA Astrophysics Data System (ADS)

Knížek, Karel; Jirák, Zdeněk; Hejtmánek, Jiří; Novák, Pavel

2010-05-01

We have analyzed, using the theoretical GGA+U calculations, different configurations of spin states (low-spin, LS; intermediate-spin, IS and high-spin, HS Co) and proposed a model that accounts for magnetic and electric transport properties of perovskite cobaltites upon doping by charge carriers. In particular, it appears that the compositional transition from the diamagnetic LS phase of LaCoO3 to the ferromagnetic metallic IS phase in La1-xSrxCoO3 ( x>0.2) involves the same mechanisms as the high-temperature transition in pure LaCoO3. The process occurs gradually via a phase-separated state, where metallic IS domains stabilized through a charge transfer between Co and Co neighbors coexist with the Co poor regions in the LS ground state (or at higher temperatures, in mixed LS/HS state). This phase separation vanishes when doping in La1-xSrxCoO3 reaches x˜0.2, and a uniform IS phase, analogous to that in pure LaCoO3 in the high-temperature limit, is established.

nomalous Interface and Surface Strontium Segregation in (La 1-ySr y) 2CoO 4 /La 1-xSr xCoO 3- Heterostructured Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Zhenxing; Yacoby, Yuzhak; Gadre, Milind

2014-01-01

Heterostructured materials have shown unusual physiochemical properties at the interfaces such as two dimensional electron gas systems, high-temperature superconductivity, and enhanced catalysis. Here we report the first atomic-scale evidence of the microscopic structure of a perovskite/Ruddlesden-Popper heterostructure (having La1-xSrxCoO3- /(La1-ySry)2CoO4 ), and anomalous strontium segregation at the interface and in the Ruddlesden-Popper structure using direct X-ray methods combined with ab initio calculations. The remarkably enhanced activity of such heterostructured surfaces relative to bulk perovskite and Ruddlesden-Popper oxides previously shown for oxygen electrocatalysis at elevated temperatures can be attributed to reduced thermodynamic penalty of oxygen vacancies in the oxide structure associatedmore » with Sr segregation observed in the heterostructure. Our findings provide insights for the design of highly active catalysts for energy conversion and storage applications.« less

1-(2-Hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione Induces G1 Cell Cycle Arrest and Autophagy in HeLa Cervical Cancer Cells.

PubMed

Tsai, Jie-Heng; Hsu, Li-Sung; Huang, Hsiu-Chen; Lin, Chih-Li; Pan, Min-Hsiung; Hong, Hui-Mei; Chen, Wei-Jen

2016-08-05

The natural agent, 1-(2-hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione (HMDB), has been reported to have growth inhibitory effects on several human cancer cells. However, the role of HMDB in cervical cancer remains unclear. Herein, we found that HMDB dose- and time-dependently inhibited growth of HeLa cervical cancer cells, accompanied with G1 cell cycle arrest. HMDB decreased protein expression of cyclins D1/D3/E and cyclin-dependent kinases (CDKs) 2/4/6 and reciprocally increased mRNA and protein levels of CDK inhibitors (p15, p16, p21, and p27), thereby leading to the accumulation of hypophosphorylated retinoblastoma (Rb) protein. HMDB also triggered the accumulation of acidic vesicles and formation of microtubule-associated protein-light chain 3 (LC3), followed by increased expression of LC3 and Beclin-1 and decreased expression of p62, suggesting that HMDB triggered autophagy in HeLa cells. Meanwhile, suppression of the expression of survivin and Bcl-2 implied that HMDB-induced autophagy is tightly linked to apoptosis. Exploring the action mechanism, HMDB induced autophagy via the modulation of AMP-activated protein kinase (AMPK) and mTOR signaling pathway rather than the class III phosphatidylinositol 3-kinase pathway. These results suggest that HMDB inhibits HeLa cell growth by eliciting a G1 arrest through modulation of G1 cell cycle regulators and by concomitantly inducing autophagy through the mediation of AMPK-mTOR and Akt-mTOR pathways, and may be a promising antitumor agent against cervical cancer.

Structural and magnetic aspects of La4(Co1-xNix)3O10+δ (0 ≤ x ≤ 1)

NASA Astrophysics Data System (ADS)

Nagell, Marius Uv; Kumar, Susmit; Sørby, Magnus H.; Fjellvåg, Helmer; Olafsen Sjåstad, Anja

2015-10-01

The Ruddlesden-Popper (RP3) type oxides, La4Co3O10+δ and La4Ni3O10+δ, form a complete solid solution. Powder X-ray and neutron diffraction data show that La4(Co1-xNix)3O10+δ is isostructural to the monoclinic La4Co3O10+δ structure (P21/a) described for all compositions without any further structural distortions as suggested in the literature. A slight elongation of the Co/Ni-O bonds facing the rock salt interlayer occurs for Ni-rich compositions. The magnetic properties of the solid solution series are mapped in the temperature range from 4 to 300 K, and the results are presented in a magnetic phase diagram. Three regimes with antiferromagnetic order (AF) exist at low temperatures, TN < 10 - 30 K. For x = 0.00, the AF is ascribed to Co(II), whereas a broader AF regime around x = 0.50 is ascribed mainly to Ni(II). Pauli paramagnetism is observed close to metallic La4Ni3O10+δ, x > 0.80. The possibility to tune the oxidation state of the transition metal atoms is demonstrated for La4Co3O10+δ, and exemplified by weakening of a temperature-induced spin transition at around 480 K.

CELF1 preferentially binds to exon-intron boundary and regulates alternative splicing in HeLa cells.

PubMed

Xia, Heng; Chen, Dong; Wu, Qijia; Wu, Gang; Zhou, Yanhong; Zhang, Yi; Zhang, Libin

2017-09-01

The current RIP-seq approach has been developed for the identification of genome-wide interaction between RNA binding protein (RBP) and the bound RNA transcripts, but still rarely for identifying its binding sites. In this study, we performed RIP-seq experiments in HeLa cells using a monoclonal antibody against CELF1. Mapping of the RIP-seq reads showed a biased distribution at the 3'UTR and intronic regions. A total of 15,285 and 1384 CELF1-specific sense and antisense peaks were identified using the ABLIRC software tool. Our bioinformatics analyses revealed that 5' and 3' splice site motifs and GU-rich motifs were highly enriched in the CELF1-bound peaks. Furthermore, transcriptome analyses revealed that alternative splicing was globally regulated by CELF1 in HeLa cells. For example, the inclusion of exon 16 of LMO7 gene, a marker gene of breast cancer, is positively regulated by CELF1. Taken together, we have shown that RIP-seq data can be used to decipher RBP binding sites and reveal an unexpected landscape of the genome-wide CELF1-RNA interactions in HeLa cells. In addition, we found that CELF1 globally regulates the alternative splicing by binding the exon-intron boundary in HeLa cells, which will deepen our understanding of the regulatory roles of CELF1 in the pre-mRNA splicing process. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of the LaComm 1.0, A French medical communication analysis software: A study assessing its sensitivity to change.

PubMed

Gibon, Anne-Sophie; Durieux, Jean-François; Merckaert, Isabelle; Delvaux, Nicole; Farvacques, Christine; Libert, Yves; Marchal, Serge; Moucheux, Angélique; Slachmuylder, Jean-Louis; Razavi, Darius

2017-02-01

To test and compare the sensitivity to change of a communication analysis software, the LaComm 1.0, to the CRCWEM's using data from a randomized study assessing the efficacy of a communication skills training program designed for nurses. The program assessment included the recording of two-person simulated interviews at baseline and after training or 3 months later. Interview transcripts were analyzed using the CRCWEM and the LaComm 1.0 tools. One hundred and nine oncology nurses (mainly graduated or certified) were included in the study. The CRCWEM detected 5 changes out of 13 expected changes (38%) (e.g., more open directive questions after training) and the LaComm 1.0, 4 changes out of 7 expected changes (57%) (e.g., more empathic statements after training). For open directive question, the effect sizes of the group-by-time changes were slightly different between tools (CRCWEM: Cohen's d=0.97; LaComm 1.0: Cohen's d=0.67). This study shows that the LaComm 1.0 is sensitive to change. The LaComm 1.0 is a valid method to assess training effectiveness in French. The use of the Lacomm 1.0 in future French communication skills training programs will allow comparisons of studies. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Metal ion displacements in noncentrosymmetric chalcogenides La{sub 3}Ga{sub 1.67}S{sub 7}, La{sub 3}Ag{sub 0.6}GaCh{sub 7} (Ch=S, Se), and La{sub 3}MGaSe{sub 7} (M=Zn, Cd)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iyer, Abishek K.; Yin, Wenlong; Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900

The quaternary Ga-containing chalcogenides La{sub 3}Ag{sub 0.6}GaS{sub 7}, La{sub 3}Ag{sub 0.6}GaSe{sub 7}, La{sub 3}ZnGaSe{sub 7}, and La{sub 3}CdGaSe{sub 7}, as well as the related ternary chalcogenide La{sub 3}Ga{sub 1.67}S{sub 7}, were prepared by reactions of the elements at 950 °C. They adopt noncentrosymmetric hexagonal structures (space group P6{sub 3}, Z=2) with cell parameters (a=10.2 Å, c=6.1 Å for the sulfides; a=10.6 Å, c=6.4 Å for the selenides) that are largely controlled by the geometrical requirements of one-dimensional stacks of Ga-centered tetrahedra separated by the La atoms. Among these compounds, which share the common formulation La{sub 3}M{sub 1–x}GaCh{sub 7} (M=Ga, Ag,more » Zn, Cd; Ch=S, Se), the M atoms occupy sites within a stacking of trigonal antiprisms formed by Ch atoms. The location of the M site varies between extremes with trigonal antiprismatic (CN6) and trigonal planar (CN3) geometry. Partial occupation of these sites and intermediate ones accounts for the considerable versatility of these structures and the occurrence of large metal displacement parameters. The site occupations can be understood in a simple way as being driven by the need to satisfy appropriate bond valence sums for both the M and Ch atoms. Band structure calculations rationalize the substoichiometry observed in the Ag-containing compounds (La{sub 3}Ag{sub 0.6}GaS{sub 7}, La{sub 3}Ag{sub 0.6}GaSe{sub 7}) as a response to overbonding. X-ray photoelectron spectroscopy supports the presence of monovalent Ag atoms in these compounds, which are not charge-balanced. - Graphical abstract: Partial occupation of metal atoms in multiple sites accounts for versatility in Ga-containing chalcogenides La{sub 3}M{sub 1–x}GaCh{sub 7} with noncentrosymmetric hexagonal structures. - Highlights: • La{sub 3}M{sub 1–x}GaCh{sub 7} (M =Ga, Ag, Zn, Cd; Ch =S, Se) adopt related hexagonal structures. • Large displacements of M atoms originate from partial occupation of

Spin and orbital ordering in Y 1-xLa xVO₃

DOE PAGES

Yan, J.-Q.; Zhou, J.-S.; Cheng, J. G.; ...

2011-12-02

The spin and orbital ordering in Y 1-xLa xVO₃ (0.30 ≤ x ≤ 1.0) has been studied to map out the phase diagram over the whole doping range 0 ≤ x ≤ 1. The phase diagram is compared with that for RVO₃ (R = rare earth or Y) perovskites without A-site variance. For x > 0.20, no long-range orbital ordering was observed above the magnetic ordering temperature T N; the magnetic order is accompanied by a lattice anomaly at a Tt ≤ T N as in LaVO₃. The magnetic ordering below Tt ≤ T N is G type in themore » compositional range 0.20 ≤ x ≤ 0.40 and C type in the range 0.738 ≤ x ≤ 1.0. Magnetization and neutron powder diffraction measurements point to the coexistence below T N of the two magnetic phases in the compositional range 0.4 < x < 0.738. Samples in the compositional range 0.20 < x ≤ 1.0 are characterized by an additional suppression of a glasslike thermal conductivity in the temperature interval T N < T < T* and a change in the slope of 1/χ(T). We argue that T* represents a temperature below which spin and orbital fluctuations couple together via λL∙S.« less

Chemical synthesis of La1 isolated from the venom of the scorpion Liocheles australasiae and determination of its disulfide bonding pattern.

PubMed

Nagao, Junya; Miyashita, Masahiro; Nakagawa, Yoshiaki; Miyagawa, Hisashi

2015-08-01

La1 is a 73-residue cysteine-rich peptide isolated from the scorpion Liocheles australasiae venom. Although La1 is the most abundant peptide in the venom, its biological function remains unknown. Here, we describe a method for efficient chemical synthesis of La1 using the native chemical ligation (NCL) strategy, in which three peptide components of less than 40 residues were sequentially ligated. The peptide thioester necessary for NCL was synthesized using an aromatic N-acylurea approach with Fmoc-SPPS. After completion of sequential NCL, disulfide bond formation was carried out using a dialysis method, in which the linear peptide dissolved in an acidic solution was dialyzed against a slightly alkaline buffer to obtain correctly folded La1. Next, we determined the disulfide bonding pattern of La1. Enzymatic and chemical digests of La1 without reduction of disulfide bonds were analyzed by liquid chromatography/mass spectrometry (LC/MS), which revealed two of four disulfide bond linkages. The remaining two linkages were assigned based on MS/MS analysis of a peptide fragment containing two disulfide bonds. Consequently, the disulfide bonding pattern of La1 was found to be similar to that of a von Willebrand factor type C (VWC) domain. To our knowledge, this is the first report of the experimental determination of the disulfide bonding pattern of peptides having a single VWC domain as well as their chemical synthesis. La1 synthesized in this study will be useful for investigation of its biological role in the venom. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd.

2:1 Charge disproportionation in perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Haichuan; Hosaka, Yoshiteru; Seki, Hayato

La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. The compound crystallizes in a √2a×2a×√2a perovskite cell in which the La and Ca ions at the A site are disordered. At 217 K the Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and this disproportionation is accompanied by transitions in magnetic and transport properties. The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. The local electronic and magnetic environments of Fe in La{sub 1/3}Ca{sub 2/3}FeO{submore » 3} are quite similar to those of Fe in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}, and the 2:1 charge disproportionation pattern of Fe{sup 3+} and Fe{sup 5+} in La{sub 1/3}Ca{sub 2/3}FeO{sub 3} is also the same as that in La{sub 1/3}Sr{sub 2/3}FeO{sub 3}. - Graphical abstract: The perovskite-structure oxide La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} shows charge disproportionation to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1, and the charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. - Highlights: • La{sub 1/3}Ca{sub 2/3}FeO{sub 3} with unusually-high-valence Fe{sup 3.67+} was synthesized at a high pressure and high temperature. • At 217 K the Fe{sup 3.67+} shows charge disproportionation (CD) to Fe{sup 3+} and Fe{sup 5+} in a ratio of 2:1. • The charge-disproportionated Fe{sup 3+} and Fe{sup 5+} are arranged along the <111> direction of the cubic perovskite cell. • The disproportionation is accompanied by transitions in magnetic and transport properties.« less

Successive magnetic transitions of the pseudo-ternary compounds Ho1-xRxRh2Si2 (R=Y, La)

NASA Astrophysics Data System (ADS)

Shigeoka, Toru; Uchima, Kiyoharu; Uwatoko, Yoshiya

2018-05-01

Magnetic measurements on the pseudo-ternary compounds Ho1-xRxRh2Si2 (R = Y or La = Y or La) were performed in order to get information on the origin of "the successive component-separated magnetic transitions" which appear in HoRh2Si2. The lattice parameters a and c remain almost constant during changes to Y composition x, while they increase with increasing La composition x. The c/a ratios are also constant in the Y-system, and they increase with increasing x in the La-system especially for above around x = 0.4. The transition temperatures, TN1 = 29.1 K, Tt = 27.3 K and TN2 =12.1 K at x = 0, decrease with increasing x. The rates of decrease for TN1 and TN2 in the Y-system accord with those in the La system below x = 0.4. The critical compositions for TN1 and TN2 are determined to be xN1 = 0.88 and xN2 = 0.59 in the La-system, respectively, and xN1 = 0.98 and xN2 = 0.75 in the Y-system. In both the systems, "the successive component-separated magnetic transitions" appear for the wide x regions. The magnetic ordered state persists in very dilute Ho-compounds in spite of much weak magnetic interactions. The effective magnetic moments are almost constant for the ordered compounds; μeff = 10.6 ± 0.30 μB/Ho. These behaviors are strange, indicating a strong correlation exists in these systems.

Electrical properties of the LaLi y Co1 - y O3 - δ (0 ≤ y ≤ 0.10) oxides

NASA Astrophysics Data System (ADS)

Vecherskii, S. I.; Konopel'ko, M. A.; Batalov, N. N.; Antonov, B. D.; Reznitskikh, O. G.; Yaroslavtseva, T. V.

2017-08-01

The effect of the Li ion concentration on the phase composition, the electrical conductivity, and the thermoelectric power of the LaLi y Co1- y O3-δ (0 ≤ y ≤ 0.1) oxides synthesized by cocrystallization has been studied. It is found that the region of the perovskite-like solid solution LaLi y Co1- y O3-δ is no higher than y = 0.037. In the temperature range 300-1020 K, lithium alloying leads to an increase in the electrical conductivity and a decrease in the positive thermoelectric power of the single-phase samples compared to LaCoO3-δ. The results are discussed using the density of states model proposed by Senarus Rodriguez and Goodenough for LaCoO3-δ and La1- x Sr x CoO3-δ and using the Mott theory of noncrystalline substances.

Syntheses and luminescence study for La{sub 1−x}Eu{sub x}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O (0≤x≤0.40) and the dehydrated products β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9} (0≤x≤0.15)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Xiaorui; Zhou, Zhengyang; Yang, Haixia

La{sub 1−x}Eu{sub x}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O with the Eu{sup 3+}-doping upper limit of 40 atom% were synthesized hydrothermally. Thereafter, thermal treatments at 710 °C were applied to obtain β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9}. The solid solution range is even narrower, i.e. 0≤x≤0.15, due to the mismatch between La{sup 3+} and Eu{sup 3+}. The host borate system shows a typical concentration quenching effect at x=0.20 under CT excitation, and this is postponed to x=0.30 under the f−f excitation. β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9} shows a very intense absorption of charge transfer, and gives strong red emissions at 615 nm withmore » large R/O ratios (1.9–2.4). The saturation effect appears at x=0.11, which is probably due to the lattice distortion. Eu{sup 3+} luminescence was applied as the structural probe to study the local coordination environment change during the dehydration and re-crystallization processes of La{sub 0.93}Eu{sub 0.07}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O. - Highlights: • La{sub 1−x}Eu{sub x}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O (0≤x≤0.40) were prepared by hydrothermal method. • The Eu{sup 3+}-doping limit in β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9} is 15 atom% proved by powder XRD. • La{sub 1−x}Eu{sub x}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O show relatively weaker red emissions. • β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9} shows an intense CT absorption together with strong red emissions. • Eu{sup 3+} luminescence was studied when annealing La{sub 0.93}Eu{sub 0.07}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O.« less

Application of Al-2La-1B Grain Refiner to Al-10Si-0.3Mg Casting Alloy

NASA Astrophysics Data System (ADS)

Jing, Lijun; Pan, Ye; Lu, Tao; Li, Chenlin; Pi, Jinhong; Sheng, Ningyue

2018-05-01

This paper reports the application and microstructure refining effect of an Al-2La-1B grain refiner in Al-10Si-0.3Mg casting alloy. Compared with the traditional Al-5Ti-1B refiner, Al-2La-1B refiner shows better performances on the grain refinement of Al-10Si-0.3Mg alloy. Transmission electron microscopy analysis suggests that the crystallite structure features of LaB6 are beneficial to the heterogeneous nucleation of α-Al grains. Regarding the mechanical performances, tensile properties of Al-10Si-0.3Mg casting alloy are prominently improved, due to the refined microstructures.

Impact of concomitant Y and Mn substitution on superconductivity in La1 -yYyFe1 -xMnxAsO0.89F0.11

NASA Astrophysics Data System (ADS)

Kappenberger, Rhea; Hammerath, Franziska; Rousse, Pierre; Afrassa, Mesfin Asfaw; Haghighi, M. Hossein; Kamusella, Sirko; Prando, Giacomo; Lamura, Gianrico; Wolter, Anja U. B.; Moroni, Matteo; Sanna, Samuele; Carretta, Pietro; Hess, Christian; Grafe, Hans-Joachim; Klauss, Hans-Henning; Wurmehl, Sabine; Büchner, Bernd

2018-02-01

We discuss the impact of concomitant substitution of Fe by Mn and La by Y in optimally F-doped LaFeAsO0.89F0.11 . Mn has a known poisoning effect on superconductivity which is particularly strong in the La1111 system, where 0.2% of Mn were reported to completely suppress superconductivity. Through isovalent substitution of La by the much smaller Y we are able to inflict chemical pressure on the structure, which we show is stabilizing the superconducting state, resulting in a drastically larger amount of Mn needed to completely quench superconductivity. Interestingly, we find that the lattice parameter c changes significantly even for small amounts of Mn substitution within a series, which is unexpected taking only the differences between ionic radii into account. We discuss our findings in the light of electron localization caused by small amounts of paramagnetic Mn impurities in La1 -yYyFe1 -xMnxAsO0.89F0.11 also indicated by resistivity and Mößbauer measurements.

Electrical conduction mechanism of LaNi{sub x}Me{sub 1−x}O{sub 3−δ} (Me = Fe, Mn)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niwa, Eiki, E-mail: e-niwa@phys.chs.nihon-u.ac.jp; Department of Integrated Sciences in Physics and Biology, College of Humanities and Sciences, Nihon University, Setagaya-ku, Tokyo 156-8550; Maeda, Hiroki

Graphical abstract: Compositional dependence of (a) electrical conductivity and (b) E{sub a} for hopping conduction of LaNi{sub x}Me{sub 1−x}O{sub 3} (Me = Fe, Mn). - Highlights: • Electrical conduction mechanism of LaNi{sub x}Me{sub 1−x}O{sub 3} (Me = Fe, Mn) was investigated. • Hopping conduction model could be applied for conductivity of both specimens. • The difference of E{sub a} due to that of energy level of Fe and Mn was observed. • Hole concentration estimated by iodimetry increases with increasing Ni content. - Abstract: Electrical conduction mechanism of LaNi{sub x}Fe{sub 1−x}O{sub 3−δ} and LaNi{sub x}Mn{sub 1−x}O{sub 3+δ} expected as Sr-freemore » new cathode material for solid oxide fuel cells was analyzed. Electrical conduction behaviors of both specimens could be well fitted by small polaron hopping conduction model. The electrical conductivity of LaNi{sub x}Fe{sub 1−x}O{sub 3−δ} increased with increasing Ni content, showing agreement with decrease of activation energy for hopping conduction. The decrease of electrical conductivity and increase of activation energy of LaNi{sub x}Mn{sub 1−x}O{sub 3+δ} were observed with increasing Ni content for 0.0 ≤ x ≤ 0.4. Further Ni substitution increased electrical conductivity and decreased activation energy for 0.4 ≤ x ≤ 0.6. It was revealed using iodometry that the difference of hole carrier density between LaNi{sub x}Fe{sub 1−x}O{sub 3−δ} and LaNi{sub x}Mn{sub 1−x}O{sub 3+δ} was small. It was suspected that the origin of the difference of electrical conduction behavior of LaNi{sub x}Fe{sub 1−x}O{sub 3−δ} and LaNi{sub x}Mn{sub 1-x}O{sub 3+δ} was difference of energy level of e{sub g} band composed of Fe 3d or Mn 3d orbitals and their overlapping quantity with O 2p and Ni 3d band.« less

Remarkably robust and correlated coherence and antiferromagnetism in (Ce 1-xLa x)Cu 2Ge 2

DOE PAGES

Hodovanets, H.; Bud’ko, S. L.; Straszheim, W. E.; ...

2015-06-08

We present magnetic susceptibility, resistivity, specific heat, and thermoelectric power measurements on (Ce 1-xLa x)Cu 2Ge 2 single crystals (0 ≤ x ≤ 1). With La-substitution, the antiferromagnetic temperature T N is suppressed in an almost linear fashion and moves below 0.36 K, the base temperature of our measurements for x > 0.8. Surprisingly, in addition to robust antiferromagnetism, the system also shows low temperature coherent scattering below T coh up to ~0.9 of La, indicating a small percolation limit ~9% of Ce. T coh as a function of magnetic field was found to have different behavior for x 0.9. Remarkably, (T coh) 2 at H = 0 was found to be linearly proportional to T N. In conclusion, the jump in the magnetic specific heat δC m at T N as a function of T K/T N for (Ce 1-xLa x)Cu 2Ge 2 follows the theoretical prediction based on the molecular field calculation for the S = 1/2 resonant level model.« less

Bile Salt Hydrolase Activities: A Novel Target to Screen Anti-Giardia Lactobacilli?

PubMed Central

Allain, Thibault; Chaouch, Soraya; Thomas, Myriam; Travers, Marie-Agnès; Valle, Isabelle; Langella, Philippe; Grellier, Philippe; Polack, Bruno; Florent, Isabelle; Bermúdez-Humarán, Luis G.

2018-01-01

Giardia duodenalis is a protozoan parasite responsible for giardiasis, a disease characterized by intestinal malabsorption, diarrhea and abdominal pain in a large number of mammal species. Giardiasis is one of the most common intestinal parasitic diseases in the world and thus a high veterinary, and public health concern. It is well-established that some probiotic bacteria may confer protection against this parasite in vitro and in vivo and we recently documented the implication of bile-salt hydrolase (BSH)-like activities from strain La1 of Lactobacillus johnsonii as mediators of these effects in vitro. We showed that these activities were able to generate deconjugated bile salts that were toxic to the parasite. In the present study, a wide collection of lactobacilli strains from different ecological origins was screened to assay their anti-giardial effects. Our results revealed that the anti-parasitic effects of some of the strains tested were well-correlated with the expression of BSH-like activities. The two most active strains in vitro, La1 and Lactobacillus gasseri CNCM I-4884, were then tested for their capacity to influence G. duodenalis infection in a suckling mice model. Strikingly, only L. gasseri CNCM I-4884 strain was able to significantly antagonize parasite growth with a dramatic reduction of the trophozoites load in the small intestine. Moreover, this strain also significantly reduced the fecal excretion of Giardia cysts after 5 days of treatment, which could contribute to blocking the transmission of the parasite, in contrast of La1 where no effect was observed. This study represents a step toward the development of new prophylactic strategies to combat G. duodenalis infection in both humans and animals. PMID:29472903

Metal-insulator transition, giant negative magnetoresistance, and ferromagnetism in LaCo1-yNiyO3

NASA Astrophysics Data System (ADS)

Hammer, D.; Wu, J.; Leighton, C.

2004-04-01

We have investigated the transport and magnetic properties of the perovskite LaCo1-yNiyO3, an alloy of LaCoO3 (a semiconductor that exhibits spin-state transitions) and LaNiO3 (a paramagnetic metal). The metal-insulator transition (MIT) was found to occur at y=0.40. On the insulating side of the transition the conductivity obeys Mott variable range hopping with a characteristic temperature (T0) that varies with y in a manner consistent with the predictions of the scaling theory of electron localization. On the metallic side the low temperature conductivity (down to 0.35 K) varies as T1/2 due to the effects of electron-electron interaction in the presence of disorder. The composition dependence of the low-temperature conductivity in the critical region fits the scaling theory of electron localization with a conductivity critical exponent close to unity, consistent with the scaling of T0 in the insulating phase. A large negative magnetoresistance is observed (up to 70% in 17 T) which increases monotonically with decreasing temperature and is smoothly decreased through the MIT. The magnetic properties show that doping LaCoO3 with Ni leads to a rapid destruction of the low spin-state for Co3+ ions, followed by the onset of distinct ferromagnetic interactions at higher Ni content. Similar to La1-xSrxCoO3, the system shows a smooth evolution from spin-glass to ferromagnetic ground states, which is interpreted in terms of the formation of ferromagnetic clusters. In contrast to La1-xSrxCoO3 further doping does not lead to a bulk ferromagnetlike state with a large TC, despite the clear existence of ferromagnetic interactions. We suggest that this is due to a limitation of the strength of the ferromagnetic interactions, which could be related to the fact that Ni rich clusters are not thermodynamically stable. The ferromagnetic clusters in LaCo1-yNiyO3 do not percolate with increasing y explaining the lack of a high-TC ferromagnetic state and the fact that the MIT is a simple

Positive magnetoresistance of single-crystal bilayer manganites (La{sub 1−z}Nd{sub z}){sub 1.4}Sr{sub 1.6}Mn{sub 2}O{sub 7} (z = 0, 0.1)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaykhutdinov, K. A.; Petrov, M. I.; Terent'ev, K. I.

2015-04-28

We investigate magnetoresistance, ρ{sub c}, of single-crystal bilayer lanthanum manganites (La{sub 1−z}Nd{sub z}){sub 1.4}Sr{sub 1.6}Mn{sub 2}O{sub 7} (z = 0 and 0.1) at a transport current flowing along the crystal c axis and in external magnetic fields applied parallel to the crystal c axis or ab plane. It is demonstrated that the La{sub 1.4}Sr{sub 1.6}Mn{sub 2}O{sub 7} manganite exhibits the positive magnetoresistance effect in the magnetic field applied in the ab sample plane at the temperatures T < 60 K, along with the negative magnetoresistance typical of all the substituted lanthanum manganites. In the (La{sub 0.9}Nd{sub 0.1}){sub 1.4}Sr{sub 1.6}Mn{sub 2}O{sub 7} sample, the positive magnetoresistancemore » effect is observed at temperatures of 60–80 K in an applied field parallel to the c axis. The mechanism of this effect is shown to be fundamentally different from the colossal magnetoresistance effect typical of lanthanum manganites. The positive magnetoresistance originates from spin-dependent tunneling of carriers between the manganese-oxygen bilayers and can be explained by features of the magnetic structure of the investigated compounds.« less

Ablation Behavior of Plasma-Sprayed La1-xSrxTiO3+δ Coating Irradiated by High-Intensity Continuous Laser.

PubMed

Zhu, Jinpeng; Ma, Zhuang; Gao, Yinjun; Gao, Lihong; Pervak, Vladimir; Wang, Lijun; Wei, Chenghua; Wang, Fuchi

2017-10-11

Laser protection for optical components, particularly those in high-power laser systems, has been a major concern. La 1-x Sr x TiO 3+δ with its good optical and thermal properties can be potentially applied as a high-temperature optical protective coating or high-reflectivity material for optical components. However, the high-power laser ablation behavior of plasma-sprayed La 1-x Sr x TiO 3+δ (x = 0.1) coatings has rarely been investigated. Thus, in this study, laser irradiation experiments were performed to study the effect of high-intensity continuous laser on the ablation behavior of the La 1-x Sr x TiO 3+δ coating. The results show that the La 1-x Sr x TiO 3+δ coating undergoes three ablation stages during laser irradiation: coating oxidation, formation and growth of new structures (columnar and dendritic crystals), and mechanical failure. A finite-element simulation was also conducted to explore the mechanism of the ablation damage to the La 1-x Sr x TiO 3+δ coating and provided a good understanding of the ablation behavior. The apparent ablation characteristics are attributed to the different temperature gradients determined by the reflectivity and thermal diffusivity of the La 1-x Sr x TiO 3+δ coating material, which are critical factors for improving the antilaser ablation property. Now, the stainless steel substrate deposited by it can effectively work as a protective shield layer against ablation by laser irradiation.

Spin glass-like properties and exchange bias in La1.5Sr0.5CoIrO6

NASA Astrophysics Data System (ADS)

Coutrim, L. T.; Bittar, E. M.; Baggio-Saitovitch, E.; Bufaiçal, L.

2017-11-01

In this work we report the synthesis and investigation of magnetic properties of La1.5Sr0.5CoIrO6. Study of temperature dependent magnetization on this double-perovskite compound revealed two anomalies at T ≃ 88 K and T ≃ 68 K, probably related to antiferromagnetic and ferromagnetic couplings of Co and Ir ions, respectively. At T ≃ 27 K there is another anomaly, which was confirmed by means of ac magnetic susceptibility measurements to be related to the emergence of a spin glass(SG)-like phase. Magnetization as a function of applied magnetic field measurements revealed exchange bias effect of the same order of magnitude of that found for La1.5Ca0.5CoIrO6 analogue compound. We compare our results for La1.5Sr0.5CoIrO6 with those reported for La1.5Ca0.5CoIrO6, and discuss the magnetic properties of both materials in terms of their structural and electronic properties.

Electrocatalytic performances of LaNi1-xMgxO3 perovskite oxides as bi-functional catalysts for lithium air batteries

NASA Astrophysics Data System (ADS)

Du, Zhenzhen; Yang, Peng; Wang, Long; Lu, Yuhao; Goodenough, J. B.; Zhang, Jian; Zhang, Dawei

2014-11-01

Mg-doped perovskite oxides LaNi1-xMgxO3 (x = 0, 0.08, 0.15) electrocatalysts are synthesized by a sol-gel method using citric acid as complex agent and ethylene glycol as thickening agent. The intrinsic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity of as-prepared perovskite oxides in aqueous electrolyte are examined on a rotating disk electrode (RDE) set up. Li-air primary batteries on the basis of Mg-doped perovskite oxides LaNi1-xMgxO3 (x = 0, 0.08, 0.15) and nonaqueous electrolyte are also fabricated and tested. In terms of the ORR current densities and OER current densities, the performance is enhanced in the order of LaNiO3, LaNi0.92Mg0.08O3 and LaNi0.85Mg0.15O3. Most notably, partially substituting nickel with magnesium suppresses formation of Ni2+ and ensures high concentration of both OER and ORR reaction energy favorable Ni3+ (eg = 1) on the surface of perovskite catalysts. Nonaqueous Li-air primary battery using LaNi0.92Mg0.08O3 and LaNi0.85Mg0.15O3 as the cathode catalysts exhibit improved performances compared with LaNiO3 catalyst, which are consistent with the ORR current densities.

Quenching of giant hysteresis effects in La(1-z)Y(z)Hx switchable mirrors

PubMed

van Gogh AT; Nagengast; Kooij; Koeman; Griessen

2000-09-04

The giant intrinsic hysteresis as a function of hydrogen concentration x in the optical and electrical properties of the archetypal switchable mirror YHx is eliminated by alloying Y with the chemically similar La. The La(1-z)Y(z)Hx films with z/=0.86 is the large uniaxial lattice expansion that accompanies their fcc to hexagonal phase transition in combination with lateral clamping.

Non-Fermi liquid and heavy fermion behavior in CexLa1-xB6 with quadrupolar moments

NASA Astrophysics Data System (ADS)

Nakamura, Shintaro; Yamamoto, Harufumi; Endo, Motoki; Aoki, Haruyoshi; Kimura, Noriaki; Nojima, Tsutomu; Kunii, Satoru

2006-05-01

The electrical resistivity of the cubic Kondo system CexLa1-xB6 ( x=0.1-0.65) has been measured. Non-Fermi liquid behavior is found in paramagnetic phase I over the wide Ce concentration range. Heavy fermion behavior is found in ordered phases of Ce0.65La0.35B6. The mass enhancement of quasiparticles in this compound is strongly dependent of the magnetic field.

Magnetic and structural transitions in La1-xAxCoO3 ( A=Ca , Sr, and Ba)

NASA Astrophysics Data System (ADS)

Kriener, M.; Braden, M.; Kierspel, H.; Senff, D.; Zabara, O.; Zobel, C.; Lorenz, T.

2009-06-01

We report thermal-expansion, lattice-constant, and specific-heat data of the series La1-xAxCoO3 for 0≤x≤0.30 with A=Ca , Sr, and Ba. For the undoped compound LaCoO3 , the thermal-expansion coefficient α(T) exhibits a pronounced maximum around T=50K caused by a temperature-driven spin-state transition from a low-spin state of the Co3+ ions at low temperatures toward a higher spin state at higher temperatures. The partial substitution of the La3+ ions by divalent Ca2+ , Sr2+ , or Ba2+ ions causes drastic changes in the macroscopic properties of LaCoO3 . The large maximum in α(T) is suppressed and completely vanishes for x≳0.125 . For A=Ca three different anomalies develop in α(T) with further increasing x , which are visible in specific-heat data as well. Together with temperature-dependent x-ray data, we identify several phase transitions as a function of the doping concentration x and temperature. From these data we propose an extended phase diagram for La1-xCaxCoO3 .

High-resolution microbiome profiling uncovers Fusobacterium nucleatum, Lactobacillus gasseri/johnsonii, and Lactobacillus vaginalis associated to oral and oropharyngeal cancer in saliva from HPV positive and HPV negative patients treated with surgery and chemo-radiation

PubMed Central

Guerrero-Preston, Rafael; White, James Robert; Godoy-Vitorino, Filipa; Rodríguez-Hilario, Arnold; Navarro, Kelvin; González, Herminio; Michailidi, Christina; Jedlicka, Anne; Canapp, Sierra; Bondy, Jessica; Dziedzic, Amanda; Mora-Lagos, Barbara; Rivera-Alvarez, Gustavo; Ili-Gangas, Carmen; Brebi-Mieville, Priscilla; Westra, William; Koch, Wayne; Kang, Hyunseok; Marchionni, Luigi; Kim, Young; Sidransky, David

2017-01-01

Microbiome studies show altered microbiota in head and neck squamous cell carcinoma (HNSCC), both in terms of taxonomic composition and metabolic capacity. These studies utilized a traditional bioinformatics methodology, which allows for accurate taxonomic assignment down to the genus level, but cannot accurately resolve species level membership. We applied Resphera Insight, a high-resolution methodology for 16S rRNA taxonomic assignment that is able to provide species-level context in its assignments of 16S rRNA next generation sequencing (NGS) data. Resphera Insight applied to saliva samples from HNSCC patients and healthy controls led to the discovery that a subset of HNSCC saliva samples is significantly enriched with commensal species from the vaginal flora, including Lactobacillus gasseri/johnsonii (710x higher in saliva) and Lactobacillus vaginalis (52x higher in saliva). These species were not observed in normal saliva from Johns Hopkins patients, nor in 16S rRNA NGS saliva samples from the Human Microbiome Project (HMP). Interestingly, both species were only observed in saliva from Human Papilloma Virus (HPV) positive and HPV negative oropharyngeal cancer patients. We confirmed the representation of both species in HMP data obtained from mid-vagina (n=128) and vaginal introitus (n=121) samples. Resphera Insight also led to the discovery that Fusobacterium nucleatum, an oral cavity flora commensal bacterium linked to colon cancer, is enriched (600x higher) in saliva from a subset of HNSCC patients with advanced tumors stages. Together, these high-resolution analyses on 583 samples suggest a possible role for bacterial species in the therapeutic outcome of HPV positive and HPV negative HNSCC patients. PMID:29340028

High-resolution microbiome profiling uncovers Fusobacterium nucleatum, Lactobacillus gasseri/johnsonii, and Lactobacillus vaginalis associated to oral and oropharyngeal cancer in saliva from HPV positive and HPV negative patients treated with surgery and chemo-radiation.

PubMed

Guerrero-Preston, Rafael; White, James Robert; Godoy-Vitorino, Filipa; Rodríguez-Hilario, Arnold; Navarro, Kelvin; González, Herminio; Michailidi, Christina; Jedlicka, Anne; Canapp, Sierra; Bondy, Jessica; Dziedzic, Amanda; Mora-Lagos, Barbara; Rivera-Alvarez, Gustavo; Ili-Gangas, Carmen; Brebi-Mieville, Priscilla; Westra, William; Koch, Wayne; Kang, Hyunseok; Marchionni, Luigi; Kim, Young; Sidransky, David

2017-12-19

Microbiome studies show altered microbiota in head and neck squamous cell carcinoma (HNSCC), both in terms of taxonomic composition and metabolic capacity. These studies utilized a traditional bioinformatics methodology, which allows for accurate taxonomic assignment down to the genus level, but cannot accurately resolve species level membership. We applied Resphera Insight, a high-resolution methodology for 16S rRNA taxonomic assignment that is able to provide species-level context in its assignments of 16S rRNA next generation sequencing (NGS) data. Resphera Insight applied to saliva samples from HNSCC patients and healthy controls led to the discovery that a subset of HNSCC saliva samples is significantly enriched with commensal species from the vaginal flora, including Lactobacillus gasseri/johnsonii (710x higher in saliva) and Lactobacillus vaginalis (52x higher in saliva). These species were not observed in normal saliva from Johns Hopkins patients, nor in 16S rRNA NGS saliva samples from the Human Microbiome Project (HMP). Interestingly, both species were only observed in saliva from Human Papilloma Virus (HPV) positive and HPV negative oropharyngeal cancer patients. We confirmed the representation of both species in HMP data obtained from mid-vagina (n=128) and vaginal introitus (n=121) samples. Resphera Insight also led to the discovery that Fusobacterium nucleatum , an oral cavity flora commensal bacterium linked to colon cancer, is enriched (600x higher) in saliva from a subset of HNSCC patients with advanced tumors stages. Together, these high-resolution analyses on 583 samples suggest a possible role for bacterial species in the therapeutic outcome of HPV positive and HPV negative HNSCC patients.

High-pressure Irreversible Amorphization of La1/3NbO3

DOE Office of Scientific and Technical Information (OSTI.GOV)

I Halevy; A Hen; A Broide

2011-12-31

The crystallographic structure of La{sub 1/3}NbO{sub 3} perovskite was studied at high pressures using a diamond-anvil cell and synchrotron radiation. High-pressure energy dispersive (EDS) x-ray diffraction and high-pressure angle dispersive (ADS) x-ray diffraction revealed an irreversible amorphization at {approx}10 GPa. A large change in the bulk modulus accompanied the high-pressure amorphization.

Ab initio calculation of excess properties of La{sub 1−x}(Ln,An){sub x}PO{sub 4} solid solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yan; JARA High-Performance Computing, Schinkelstrasse 2, 52062 Aachen; Kowalski, Piotr M., E-mail: p.kowalski@fz-juelich.de

2014-12-15

We used ab initio computational approach to predict the excess enthalpy of mixing and the corresponding regular/subregular model parameters for La{sub 1−x}Ln{sub x}PO{sub 4} (Ln=Ce,…, Tb) and La{sub 1−x}An{sub x}PO{sub 4} (An=Pu, Am and Cm) monazite-type solid solutions. We found that the regular model interaction parameter W computed for La{sub 1−x}Ln{sub x}PO{sub 4} solid solutions matches the few existing experimental data. Within the lanthanide series W increases quadratically with the volume mismatch between LaPO{sub 4} and LnPO{sub 4} endmembers (ΔV=V{sub LaPO{sub 4}}−V{sub LnPO{sub 4}}), so that W(kJ/mol)=0.618(ΔV(cm{sup 3}/mol)){sup 2}. We demonstrate that this relationship also fits the interaction parameters computedmore » for La{sub 1−x}An{sub x}PO{sub 4} solid solutions. This shows that lanthanides can be used as surrogates for investigation of the thermodynamic mixing properties of actinide-bearing solid solutions. - Highlights: • The excess enthalpies of mixing for monazite-type solid solutions are computed. • The excess enthalpies increase with the endmembers volume mismatch. • The relationship derived for lanthanides is transferable to La{sub 1−x}An{sub x}PO{sub 4} systems.« less

Material properties of perovskites in the quasi-ternary system LaFeO3-LaCoO3-LaNiO3

NASA Astrophysics Data System (ADS)

Tietz, F.; Arul Raj, I.; Ma, Q.; Baumann, S.; Mahmoud, A.; Hermann, R. P.

2016-05-01

An overview is presented on the variation of electrical conductivity, oxygen permeation, and thermal expansion coefficient as a function of the composition of perovskites in the quasi-ternary system LaFeO3-LaCoO3-LaNiO3. Powders of thirteen nominal perovskite compositions were synthesized under identical conditions by the Pechini method. The powder X-ray diffraction data of two series, namely La(Ni0.5Fe0.5)1-xCoxO3 and LaNi0.5-xFexCo0.5O3, are presented after the powders had been sintered at 1100 °C for 6 h in air. The measurements revealed a rhombohedral structure for all compositions except LaNi0.5Fe0.5O3 for which 60% rhombohedral and 40% orthorhombic phase was found. The maximum DC electrical conductivity value of the perovskites at 800 °C was 1229 S cm-1 for the composition LaCoO3 and the minimum was 91 S cm-1 for the composition LaCo0.5Fe0.5O3. The oxygen permeation of samples with promising conductivities at 800 °C was one order of magnitude lower than that of La0.6Sr0.4Co0.8Fe0.2O3 (LSCF). The highest value of 0.017 ml cm-2 min-1 at 950 °C was obtained with LaNi0.5Co0.5O3. The coefficients of thermal expansion varied in the range of 13.2×10-6 K-1 and 21.9×10-6 K-1 for LaNi0.5Fe0.5O3 and LaCoO3, respectively. 57Fe Mössbauer spectroscopy was used as probe for the oxidation states, local environment and magnetic properties of iron ions as a function of chemical composition. The substitution had a great influence on the chemical properties of the materials.

Revisiting Cu 63 NMR evidence for charge order in superconducting La 1.885 Sr 0.115 CuO 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imai, T.; Takahashi, S. K.; Arsenault, A.

Here, the presence of charge and spin stripe order in the La 2CuO 4-based family of superconductors continues to lead to new insight on the unusual ground-state properties of high- T c cuprates. Soon after the discovery of charge stripe order at T charge≃65 K in Nd 3+ co-doped La 1.48Nd 0.4Sr 0.12CuO 4( Tc≃6 K), Hunt et al. demonstrated that La 1.48Nd 0.4Sr 0.12CuO 4 and superconducting La 2–xSr xCuO 4 with x~1/8( Tc≃30 K) share nearly identical NMR anomalies near Tcharge of the former. Their inevitable conclusion that La 1.885Sr 0.115CuO 4 also undergoes charge order at amore » comparable temperature became controversial, because diffraction measurements at the time were unable to detect Bragg peaks associated with charge order. Recent advances in x-ray diffraction techniques finally led to definitive confirmations of the charge order Bragg peaks in La 1.885Sr 0.115CuO 4 with an onset at as high as Tcharge≃80 K. Meanwhile, improved instrumental technology has enabled routine NMR measurements that were not feasible two decades ago. Motivated by these new developments, we revisit the charge order transition of a La 1.885Sr 0.115CuO 4 single crystal based on 63Cu NMR techniques. We demonstrate that 63Cu NMR properties of the nuclear spin I z=–1/2 to +1/2 central transition below Tcharge exhibit unprecedentedly strong dependence on the measurement time scale set by the separation time τ between the 90° and 180° radio-frequency pulses; a new kind of anomalous, very broad winglike 63Cu NMR signals gradually emerge below Tcharge only for extremely short τ≲4μs, while the spectral weight I Normal of the normal NMR signals is progressively wiped out. The NMR linewidth and relaxation rates depend strongly on τ below Tcharge, and their enhancement in the charge ordered state indicates that charge order turns on strong but inhomogeneous growth of Cu spin-spin correlations.« less

Revisiting Cu 63 NMR evidence for charge order in superconducting La 1.885 Sr 0.115 CuO 4

DOE PAGES

Imai, T.; Takahashi, S. K.; Arsenault, A.; ...

2017-12-26

Here, the presence of charge and spin stripe order in the La 2CuO 4-based family of superconductors continues to lead to new insight on the unusual ground-state properties of high- T c cuprates. Soon after the discovery of charge stripe order at T charge≃65 K in Nd 3+ co-doped La 1.48Nd 0.4Sr 0.12CuO 4( Tc≃6 K), Hunt et al. demonstrated that La 1.48Nd 0.4Sr 0.12CuO 4 and superconducting La 2–xSr xCuO 4 with x~1/8( Tc≃30 K) share nearly identical NMR anomalies near Tcharge of the former. Their inevitable conclusion that La 1.885Sr 0.115CuO 4 also undergoes charge order at amore » comparable temperature became controversial, because diffraction measurements at the time were unable to detect Bragg peaks associated with charge order. Recent advances in x-ray diffraction techniques finally led to definitive confirmations of the charge order Bragg peaks in La 1.885Sr 0.115CuO 4 with an onset at as high as Tcharge≃80 K. Meanwhile, improved instrumental technology has enabled routine NMR measurements that were not feasible two decades ago. Motivated by these new developments, we revisit the charge order transition of a La 1.885Sr 0.115CuO 4 single crystal based on 63Cu NMR techniques. We demonstrate that 63Cu NMR properties of the nuclear spin I z=–1/2 to +1/2 central transition below Tcharge exhibit unprecedentedly strong dependence on the measurement time scale set by the separation time τ between the 90° and 180° radio-frequency pulses; a new kind of anomalous, very broad winglike 63Cu NMR signals gradually emerge below Tcharge only for extremely short τ≲4μs, while the spectral weight I Normal of the normal NMR signals is progressively wiped out. The NMR linewidth and relaxation rates depend strongly on τ below Tcharge, and their enhancement in the charge ordered state indicates that charge order turns on strong but inhomogeneous growth of Cu spin-spin correlations.« less

Crystal structure, oxidation state and magnetism of Sr{sub x}La{sub 2−x}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} (x=1, 1.5)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lü, Minfeng, E-mail: m.f.lv@ciac.jl.cn; Deng, Xiaolong; Waerenborgh, João C.

2014-03-15

Sr{sub x}La{sub 2−x}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} (x=1, 1.5) oxides with K{sub 2}NiF{sub 4}-type structure were prepared by solid state reaction and characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, magnetic and electrical resistivity measurements. The SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4} phase was obtained for the first time with a negligible amount of impurities. The octahedral Cu/RuO{sub 6} units are more elongated in SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4} than in Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} indicating a greater extent of static Jahn–Teller distortion. XPS suggests that mixed ion pairs Ru{sup 5+}/Ru{sup 4+}↔Cu{sup +}/Cu{sup 2+} are present in SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4}, whilemore » Ru remains as Ru{sup 5+} and Cu as Cu{sup 2+} in Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4}. Both samples show spin-glass behavior, which can be explained by competition between ferromagnetic and antiferromagnetic superexchange interactions. The negative Weiss temperature estimated for SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4}, −318 K, is significantly lower than −11.5 K deduced for Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} which may be related to the higher static Jahn–Teller distortion in the former oxide. -- Graphical abstract: SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4} with K{sub 2}NiF{sub 4}-type structure show a larger static Jahn–Teller distortion than Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4}, which may be related to stronger antiferromagnetic superexchange interactions. Highlights: • SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4} (I) larger Jahn–Teller (J–T) distortion than Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} (II). • Octahedral Cu/RuO{sub 6} units are more elongated in I than in II. • Mixed ion pairs Ru{sup 5+}/Ru{sup 4+}↔Cu{sup +}/Cu{sup 2+} are present in I, while Ru remains as Ru{sup 5+} and Cu as Cu{sup 2+} in II. • Negative Weiss temperature of I significantly lower

Influence of nickel doping on oxygen-ionic conductivity of the n = 1 Ruddlesden-Popper Phases La{sub 1.85}Ca{sub 0.15}(Cu{sub 1−x}Ni{sub x})O{sub 4−δ} (δ = 0.0905)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Midouni, Adnene; Université de Tunis El Manar, Campus Universitaire Farhat Hached, B.P. No 94- Rommana, 1068 Tunis; Houchati, Mohamed Ikbal, E-mail: ikb_med@yahoo.fr

2016-08-15

The results of the synthesis and characterization of the optimally doped La{sub 1.85}Ca{sub 0.15}(Cu{sub 1−x}Ni{sub x})O{sub 4-δ} solid solution with x = 0, 0.1, 0.2 and 0.3 are reported. The versatility of these La{sub 1.85}Ca{sub 0.15}(Cu{sub 1−x}Ni{sub x})O{sub 4−δ} materials is explained on the basis of structural features and the ability to accommodate oxygen nonstoichiometry. According to powder X-ray and neutron diffraction data, La{sub 1.85}Ca{sub 0.15}(Cu{sub 1−x}Ni{sub x})O{sub 4−δ} adopts the tetragonal structure with oxygen vacancies occurring preferentially at the O{sub ap} sites within the {(La/Ca)O} layers of the perovskite blocks and the oxygen deviation from stoichiometry δ was foundmore » to be δ=0.0905(6). The bulk conductivity indicated an Arrhenius-type thermally activated process and oxygen vacancies are the possible ionic charge carriers at T=270 °C. An increase of the conductivity was detected when Ni was introduced. With nickel ratio variation, a strong correlation was observed between the Cu(Ni)-O{sub ap} apical bond length variation and the conductivity variation through controlling the O{sup 2−} ion migration. - Highlights: • We report the synthesis and structure of the La{sub 1.85}Ca{sub 0.15}(Cu{sub 1−x}Ni{sub x})O{sub 4−δ} (0≤x≤0.3; δ=0.0905) compounds. • La{sub 1.85}Ca{sub 0.15}(Cu{sub 1−x}Ni{sub x})O{sub 4−δ} (x=0.0, 0.2, 0.3) doped with Ni{sup 2+} have a higher conductivity than undoped La{sub 1.85}Ca{sub 0.15}CuO{sub 4−δ}. • At T=270 °C, sample x=0.3 has the highest conductivity (0.2915 sm{sup −1}).« less

Effect of Sr substitution on the room temperature electrical properties of La1-xSrxFeO3 nano-crystalline materials

NASA Astrophysics Data System (ADS)

Kafa, C. A.; Triyono, D.; Laysandra, H.

2017-07-01

LaFeO3 is a material with Perovskite structure which electrical properties got investigated a lot, because as a p-type semiconductor it showed good gas sensing behavior through resistivity comparison. Sr doping on LaFeO3 is able to improve the electrical conductivity through structural modification. Using the Sr atoms doping concentration (x) from 0.1 to 0.4, La1-xSrxFeO3 nanocrystal pellets were synthesized using sol-gel method, followed by gradual heat treatment and uniaxial compaction. Structural analysis from XRD characterization shows that the structure of the materials is Orthorhombic Perovskite. The topography of the sample by SEM reveals grain and grain boundary existence with emerging agglomeration. The electrical properties of the material, as functions of frequency, were measured by Impedance Spectroscopy method using RLC meter. Through the Nyquist plot and Bode plot, the electrical conductivity of La1-xSrxFeO3 is contributed by grain and grain boundaries. It is reported that La0.6Sr0.4FeO3 sample has the most superior electrical conductivity of all samples, and the electrical permittivity of both La0.8Sr0.2FeO3 and La0.7Sr0.3FeO3 are the most stable.

Thermodynamic modeling of the Ge-La binary system

NASA Astrophysics Data System (ADS)

Liu, Miao; Li, Chang-rong; Du, Zhen-min; Guo, Cui-ping; Niu, Chun-ju

2012-08-01

The Ge-La binary system was critically assessed by means of the calculation of phase diagram (CALPHAD) technique. The associate model was used for the liquid phase containing the constituent species Ge, La, Ge3La5, and Ge1.7La. The terminal solid solution diamond-(Ge) with a small solubility of La was described using the substitutional model, in which the excess Gibbs energy was formulated with the Redlich-Kister equation. The compounds with homogeneity ranges, α(Ge1.7La), β(Ge1.7La), and (GeLa), were modeled using two sublattices as α(Ge,La)1.7La, β(Ge,La)1.7La, and (Ge,La)(Ge,La), respectively. The intermediate phases with no solubility ranges, Ge4La5, Ge3La4, Ge3La5, and GeLa3, were treated as stoichiometric compounds. The three allotropic modifications of La, dhcp-La, fcc-La, and bcc-La, were kept as pure element phases since no solubility of Ge in La was reported. A set of self-consistent thermodynamic parameters of the Ge-La binary system was obtained. The calculation results agree well with the available experimental data from literatures.

Grain size effect on the permittivity of La1.5Sr0.5NiO4 nanoparticles

NASA Astrophysics Data System (ADS)

Dang Thanh, Tran; Van Hong, Le

2009-09-01

Using the annealing at different temperatures the La1.5Sr0.5NiO4 ceramic samples with different mean grain size were manufactured. Mean grain size () of the samples was evaluated by Warren-Averbach method and their SEM images. The obtained results of both methods are almost the same, changing from 16.2 to 95 nm in dependence on the annealing temperature. The frequency dependence of dielectric constant in the frequency range of (1-13 MHz) was recorded for all samples. The real (ɛ') and the imaginary parts (ɛ") of the permittivity of La1.5Sr0.5NiO4 samples abnormally depend on the frequency, exhibiting a dielectric resonance around 500 kHz. R-L-C in series equivalent-circuit fitted well for the obtained result. It was supposed that there exists magnetic contribution in material that suggests the material is a multiferroic one. Dependence of the (ɛ') on the mean grain size supposed that the colossal dielectric property is an intrinsic behaviour of La1.5Sr0.5NiO4 material.

Photoemission study of absorption mechanisms in Bi2.0Sr1.8Ca0.8La0.3Cu2.1O8+δ, BaBiO3, and Nd1.85Ce0.15CuO4

NASA Astrophysics Data System (ADS)

Lindberg, P. A. P.; Shen, Z.-X.; Wells, B. O.; Dessau, D. S.; Ellis, W. P.; Borg, A.; Kang, J.-S.; Mitzi, D. B.; Lindau, I.; Spicer, W. E.; Kapitulnik, A.

1989-11-01

Photoemission measurements in the constant-final-state (absorption) mode were performed on three different classes of high-temperature superconductors Bi2.0Sr1.8Ca0.8La0.3Cu2.1O8+δ, BaBiO3, and Nd1.85Ce0.15CuO4 using synchrotron radiation from 20 to 200 eV. Absorption signals from all elements but Ce are identified. The results firmly show that the Bi 6s electrons are more delocalized in BaBiO3 than in Bi2.0Sr1.8Ca0.8La0.3Cu2.1O8+δ, in agreement with the results of band-structure calculations. Differences in the absorption signals due to O and Bi excitations between BaBiO3 and Bi2.0Sr1.8Ca0.8La0.3Cu2.1O8+δ are discussed. Delayed absorption onsets attributed to giant resonances (Ba 4d-->4f, La 4d-->4f, and Nd 4d-->4f transitions) are also reported.

Soluble ephrin a1 is necessary for the growth of HeLa and SK-BR3 cells

PubMed Central

2010-01-01

Background Ephrin A1 (EFNA1) is a member of the A-type ephrin family of cell surface proteins that function as ligands for the A-type Eph receptor tyrosine kinase family. In malignancy, the precise role of EFNA1 and its preferred receptor, EPHA2, is controversial. Several studies have found that EFNA1 may suppress EPHA2-mediated oncogenesis, or enhance it, depending on cell type and context. However, little is known about the conditions that influence whether EFNA1 promotes or suppresses tumorigenicity. EFNA1 exists in a soluble form as well as a glycophosphatidylinositol (GPI) membrane attached form. We investigated whether the contradictory roles of EFNA1 in malignancy might in part be related to the existence of both soluble and membrane attached forms of EFNA1 and potential differences in the manner in which they interact with EPHA2. Results Using a RNAi strategy to reduce the expression of endogenous EFNA1 and EPHA2, we found that both EFNA1 and EPHA2 are required for growth of HeLa and SK-BR3 cells. The growth defects could be rescued by conditioned media from cells overexpressing soluble EFNA1. Interestingly, we found that overexpression of the membrane attached form of EFNA1 suppresses growth of HeLa cells in 3D but not 2D. Knockdown of endogenous EFNA1, or overexpression of full-length EFNA1, resulted in relocalization of EPHA2 from the cell surface to sites of cell-cell contact. Overexpression of soluble EFNA1 however resulted in more EPHA2 distributed on the cell surface, away from cell-cell contacts, and promoted the growth of HeLa cells. Conclusions We conclude that soluble EFNA1 is necessary for the transformation of HeLa and SK-BR3 cells and participates in the relocalization of EPHA2 away from sites of cell-cell contact during transformation. PMID:20979646

Disentangling factors that shape the gut microbiota in German Shepherd dogs

PubMed Central

Ramadan, Ziad; Li, Qinghong; Hedhammar, Åke; Reynolds, Arleigh; Spears, Julie; Labuda, Jeff; Pelker, Robyn; Björkstén, Bengt; Dicksved, Johan; Hansson-Hamlin, Helene

2018-01-01

The aim of this study was to explore the development of the gut microbiota in 168 German Shepherd dogs (30 litters) from 7 weeks to 18 months of age and furthermore, to study the effect of relatedness, maternal microbiota composition and living environment in a large and well-defined population of dogs. Using 454 pyrosequencing, we assessed the effects of pre- and postnatal probiotic supplementation (Lactobacillus johnsonii NCC533 (La1)) and analysed whether administration of the probiotic strain influenced fecal microbiota composition in a placebo controlled double-blinded study. The bitches were treated with probiotics or placebo during last trimester of pregnancy and until their puppies were 8 weeks old, the puppies received the same treatment as their mothers between 3–12 weeks of age. Samples from bitches were collected at pregnancy day 42, partum, 4 weeks postpartum and 7 weeks postpartum and from puppies at the age 4 weeks, 7 weeks, 12–13 months and 15–18 months. Serum IgA, total serum IgE, fecal IgA and IgG antibody responses against canine distemper virus were analysed by ELISA in order to detect any immune stimulating effects of the probiotic strain. Analysis of the fecal microbiota composition showed that the predominant phyla were the same in 7 weeks old puppies as in pregnant and lactating bitches (Firmicutes, Fusobacteria, Bacteroidetes). Proportions among different bacteria as well as diversity varied from 7 weeks old puppies up to 15–18 months of age. Litter mates had a more similar fecal microbiota compared to unrelated dogs and 7 weeks old puppies were more similar to their mothers than to unrelated bitches at 7 weeks postpartum but not at partum. We observed a change in the relative abundance of different bacteria during lactation, and an increase in diversity from pregnancy to end of lactation. The microbial diversity was affected by living area where dogs living in big cities had higher diversity compared to dogs living at the

Nanomagnetic Droplets and Implications to Orbital Ordering in La1-xSrxCoO3

NASA Astrophysics Data System (ADS)

Phelan, D.; Louca, Despina; Rosenkranz, S.; Lee, S.-H.; Qiu, Y.; Chupas, P. J.; Osborn, R.; Zheng, H.; Mitchell, J. F.; Copley, J. R. D.; Sarrao, J. L.; Moritomo, Y.

2006-01-01

Inelastic cold-neutron scattering on LaCoO3 provided evidence for a distinct low energy excitation at 0.6 meV coincident with the thermally induced magnetic transition. Coexisting strong ferromagnetic (FM) and weaker antiferromagnetic correlations that are dynamic follow the activation to the excited state, identified as the intermediate S=1 spin triplet. This is indicative of dynamical orbital ordering favoring the observed magnetic interactions. With hole doping as in La1-xSrxCoO3, the FM correlations between Co spins become static and isotropically distributed due to the formation of FM droplets. The correlation length and condensation temperature of these droplets increase rapidly with metallicity due to the double exchange mechanism.

Effect of Manganese Addition on the Structure, Magnetic Properties and Microwave Absorption of La0.8Ba0.2MnxFe½(1-x)Ti½(1-x)O3

NASA Astrophysics Data System (ADS)

Adi, W. A.; Indro, M. N.; Kusumastuti, A. A.

2017-03-01

We have carried out modification of La0.8Ba0.2MnxFe½(1-x)Ti½(1-x)O3 (x = 0.1 - 0.8) magnetic materials by wet milling method. Raw materials of La2O3, BaCO3, Fe2O3, TiO2 and MnCO3 were mixed according to stoichiometry calculation for each composition. The mixture was milled for 5 hours and then sintered at 1000 °C for 5 hours. The refinement results by X-ray diffraction pattern shows that the increasing Mn composition enhances the mass fraction of La0.8Ba0.2MnxFe½(1-x)Ti½(1-x)O3 phase which has the same structure as LaMnO3. For x = 0.8 a single phase of LaMnO3 was formed. The single phase has a crystal monoclinic crystal structure with space group of I 1 2 / a 1, with lattice parameters given by a = 5.519(5) Å, b = 5.5537(5) Å and c = 7.8176(9) Å, α = γ = 90o and β = 90.345(6)o, V = 239.64(3) Å3, ρ = 6.463 gr.cm-3, wRp = 5.96, and χ2 (chi-squared) = 1.17. The hysteresis curve shows that the sample with composition x = 0.8 produces ferromagnetic behaviour at room temperature. The ferromagnetic properties arise due to the mixed valence of Mn3+ and Mn4+ ions through a double exchange mechanism. The results of the microwave absorption indicated that there was a broadening of absorption peak frequency at 9.9 GHz. The reflection loss (RL) increases with the increasing of LaMnO3 phase. For x = 0.8 we have the best of RL where the microwave absorption was calculated reaching 95% at the highest peak frequency with a thickness of 1.5 mm. Thus we have been successful in creating a single phase of La0.8Ba0.2MnxFe½(1-x)Ti½(1-x)O3 with application as a microwave absorber.

Revisiting 63Cu NMR evidence for charge order in superconducting La1.885Sr0.115CuO4

NASA Astrophysics Data System (ADS)

Imai, T.; Takahashi, S. K.; Arsenault, A.; Acton, A. W.; Lee, D.; He, W.; Lee, Y. S.; Fujita, M.

2017-12-01

The presence of charge and spin stripe order in the La2CuO4 -based family of superconductors continues to lead to new insight on the unusual ground-state properties of high-Tc cuprates. Soon after the discovery of charge stripe order at Tcharge≃65 K in Nd3 + co-doped La1.48Nd0.4Sr0.12CuO4 (Tc≃6 K) [Tranquada et al., Nature (London) 375, 561 (1995), 10.1038/375561a0], Hunt et al. demonstrated that La1.48Nd0.4Sr0.12CuO4 and superconducting La2 -xSrxCuO4 with x ˜1 /8 (Tc≃30 K) share nearly identical NMR anomalies near Tcharge of the former [Phys. Rev. Lett. 82, 4300 (1999), 10.1103/PhysRevLett.82.4300]. Their inevitable conclusion that La1.885Sr0.115CuO4 also undergoes charge order at a comparable temperature became controversial, because diffraction measurements at the time were unable to detect Bragg peaks associated with charge order. Recent advances in x-ray diffraction techniques finally led to definitive confirmations of the charge order Bragg peaks in La1.885Sr0.115CuO4 with an onset at as high as Tcharge≃80 K. Meanwhile, improved instrumental technology has enabled routine NMR measurements that were not feasible two decades ago. Motivated by these new developments, we revisit the charge order transition of a La1.885Sr0.115CuO4 single crystal based on 63Cu NMR techniques. We demonstrate that 63Cu NMR properties of the nuclear spin Iz=-1/2 to +1/2 central transition below Tcharge exhibit unprecedentedly strong dependence on the measurement time scale set by the separation time τ between the 90∘ and 180∘ radio-frequency pulses; a new kind of anomalous, very broad winglike 63Cu NMR signals gradually emerge below Tcharge only for extremely short τ ≲4 μ s , while the spectral weight INormal of the normal NMR signals is progressively wiped out. The NMR linewidth and relaxation rates depend strongly on τ below Tcharge, and their enhancement in the charge ordered state indicates that charge order turns on strong but inhomogeneous growth of Cu spin

Material properties of perovskites in the quasi-ternary system LaFeO 3–LaCoO 3–LaNiO 3

DOE PAGES

Tietz, F.; Arul Raj, I.; Ma, Q.; ...

2016-02-02

We present an overview on the variation of electrical conductivity, oxygen permeation, oxygen surface exchange and thermal expansion coefficient as a function of the composition of perovskites in the quasi-ternary system LaFeO 3–LaCoO 3–LaNiO 3. Powders of thirteen nominal perovskite compositions were synthesized under identical conditions by the Pechini method. The powder X-ray diffraction data of two series, namely La(Ni 0.5Fe 0.5) 1-xCo xO 3 and LaNi 0.5- xFe xCo 0.5O 3, are presented after the powders had been sintered at 1100 C for 6 h in air. The measurements revealed a rhombohedral structure for all compositions except LaNi 0.5Femore » 0.5O 3 for which 60% rhombohedral and 40% orthorhombic phase was found. Moreover, the maximum DC electrical conductivity value of the perovskites at 800 C was 1229 S cm-1 for the composition LaCoO 3 and the minimum was 91 S cm-1 for the composition LaCo 0.5Fe 0.5O 3. The oxygen permeation of samples with promising conductivities at 800 C was one order of magnitude lower than that of La 0.6Sr 0.4Co 0.8Fe 0.2O 3 (LSCF). The highest value of 0.017 ml cm -2 min-1 at 950 C was obtained with LaNi 0.5Co 0.5O 3. The coefficients of thermal expansion varied in the range of 13.2 x 10 -6 K -1 and 21.9 x 10 -6 K -1 for LaNi 0.5Fe 0.5O 3 and LaCoO 3, respectively. 57Fe M ssbauer spectroscopy was used as probe for the oxidation states, local environment and magnetic properties of iron ions as a function of chemical composition. Ultimately, the substitution had a great influence on the chemical properties of the materials.« less

Large thermal conductivity reduction induced by La/O vacancies in the thermoelectric LaCoO3 system.

PubMed

Wang, Yang; Li, Fang; Xu, Luxiang; Sui, Yu; Wang, Xianjie; Su, Wenhui; Liu, Xiaoyang

2011-05-16

A series of compact La/O-vacant La(1-x)CoO(3-y) compounds were prepared by a cold high-pressure procedure, and their thermoelectric (TE) properties were investigated. Compared with the ion-substituted hole-type LaCoO(3) systems (e.g., La(1-x)Sr(x)CoO(3)), the thermal conduction of La(1-x)CoO(3-y) is noticeably reduced by the La/O vacancies, whereas the electric transport is less influenced, which results in an efficient ZT enhancement. We demonstrate that the large thermal conductivity reduction originates from the strong point-defect scattering, and La(1-x)CoO(3-y) can be rationalized as a partially filled solid solution: La(1-x)◻(x)CoO(3-y)◻(y), where ◻ denotes a vacancy. Such intrinsic thermal conductivity suppression provides an effective pathway for the design of better TE materials.

The synthesis and the luminescence properties of Sr2Ga3La1-xDyxGe3O14

NASA Astrophysics Data System (ADS)

Wang, Qiang; Mu, Zhongfei; Yang, Lurong; Zhang, Shaoan; Zhu, Daoyun; Yang, Yibin; Luo, Dongxiang; Wu, Fugen

2018-02-01

A series of Sr2Ga3La1-xDyxGe3O14 (x = 0, 0.015, 0.03, 0.045, 0.06, 0.075, 0.09) phosphors were synthesized by high temperature solid state reactions. X-ray diffraction analysis proves that single-phase Sr2Ga3La1-xDyxGe3O14 (0 ≤ x ≤ 0.09) has been obtained. The particle size of these powders is in the range from 1 to 3 μm. The host Sr2Ga3LaGe3O14 emits blue white light under the excitation of 260 nm ultraviolet light. Dy3+ doped samples can be effectively excited with near ultraviolet light and exhibit two emission bands in the blue (4F9/2 → 6H15/2) and yellow regions (4F9/2 → 6H13/2), which can form white light. Present research indicates that Dy3+ doped Sr2Ga3LaGe3O14 have the potential to be a single-phase full-color emitting phosphor.

New Ca-Tims and La-Icp Analyses of GJ-1, Plesovice, and FC1 Reference Materials

NASA Astrophysics Data System (ADS)

Feldman, J. D.; Möller, A.; Walker, J. D.

2014-12-01

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb zircon geochronology relies on external reference standards to monitor and correct for different mass fractionation effects and instrument drift. Common zircon reference materials used within the community, including the KU Isotope Geochemistry Laboratory, are GJ-1 (207Pb/206Pb age: 608.53 +/- 0.37Ma; Jackson et al., 2004), Plesovice (337.13 +/- 0.37 Ma; Slama et al., 2008), and FC-1 (1099.0 +/-0.6 Ma; Paces and Miller, 1993). The age distribution of zircon reference material varies slightly from sample fraction to sample fraction, and the published results for GJ-1 are slightly discordant. As a result, using the published data for the distributed standard splits can lead to small systematic variations when comparing datasets from different labs, and more high precision data are needed to evaluate potential inhomogeneity of sample splits used in different laboratories. Here we characterize these reference materials with cathodoluminescence, LA-ICP-MS traverses across grains, and high precision CA-TIMS to better constrain the ages and assess zoning of these standards, and present the data for comparison with other laboratories. Reducing systematic error by dating our own reference material lends confidence to our analyses and allows for inter-laboratory age reproducibility of unknowns. Additionally, the reduction in propagated uncertainties (especially in GJ-1, for which both the red and yellow variety will be analyzed) will be used to improve long-term reproducibility, comparisons between samples of similar age, detrital populations and composite pluton zircons. Jackson, S.E., et al., 2004, Chemical Geology, v. 211, p. 47-69. Paces, J.B. & Miller, J.D., 1993, Journal of Geophysical Research, v. 80, p. 13997-14013. Slama, J., et al., 2008, Chemical Geology, v. 249. p. 1-35.

La guerra de los Estados Unidos contra la inmigración. Efectos paradójicos1

PubMed Central

Massey, Douglas S.; Pren, Karen A.

2016-01-01

Resumen A finales de la década de los cincuenta, Estados Unidos permitía la entrada de aproximadamente medio millón de inmigrantes mexicanos al año, de los cuales 450.000 entraban con visados de trabajo temporal y 50.000 llegaban con visados de residentes permanentes. A mediados de los años sesenta, los cambios en la política migratoria de Estados Unidos realizados en nombre de los derechos civiles redujeron drásticamente las oportunidades de entrada legal a Estados Unidos. Se eliminaron los visados de trabajo temporal y se limitaron los visados de residentes a 20.000 por año. Con las oportunidades de entrada legal restringidas, los flujos migratorios ya establecidos simplemente continuaron, fuera de los límites legales, dando comienzo a una inesperada reacción en cadena de eventos que culminaron en una guerra total contra los inmigrantes y el rápido crecimiento -sin precedentes- de población residente no autorizada en Estados Unidos. El presente artículo demuestra que el aumento de inmigración indocumentada en los Estados Unidos y el crecimiento de la población sin papeles son un producto de políticas migratorias y fronterizas mal concebidas. PMID:27076695

Hybrid density functional study of structural, bonding, and electronic properties of the manganite series La1-xCaxMnO3 (x =0,1/4,1)

NASA Astrophysics Data System (ADS)

Korotana, R.; Mallia, G.; Gercsi, Z.; Liborio, L.; Harrison, N. M.

2014-05-01

Hybrid-exchange density functional theory calculations are carried out to determine the effects of A-site doping on the electronic and magnetic properties of the manganite series La1-xCaxMnO3. This study focuses on the ground state of an ordered Ca occupancy in a periodic structure. It is shown that the hybrid-exchange functional, Becke three-parameter Lee-Yang-Parr (B3LYP), provides an accurate and consistent description of the electronic structure for LaMnO3, CaMnO3, and La0.75Ca0.25MnO3. We have quantified the relevant structural, magnetic, and electronic energy contributions to the stability of the doped compound. An insight into the exchange coupling mechanism for the low hole density region of the phase diagram, where a polaron (anti-Jahn-Teller) forms, is also provided. This study completes a microscopic description of the lightly doped insulator with an antiferromagnetic-to-ferromagnetic and metal-to-insulator transition.

MCPIP1 contributes to the toxicity of proteasome inhibitor MG-132 in HeLa cells by the inhibition of NF-κB.

PubMed

Skalniak, Lukasz; Dziendziel, Monika; Jura, Jolanta

2014-10-01

Recently, we have shown that the treatment of cells with proteasome inhibitor MG-132 results in the induction of expression of monocyte chemotactic protein-1 induced protein 1 (MCPIP1). MCPIP1 is a ribonuclease, responsible for the degradation of transcripts encoding certain pro-inflammatory cytokines. The protein is also known as an inhibitor of NF-κB transcription factor. Thanks to its molecular properties, MCPIP1 is considered as a regulator of inflammation, differentiation, and survival. Using siRNA technology, we show here that MCPIP1 expression contributes to the toxic properties of MG-132 in HeLa cells. The inhibition of proteasome by MG-132 and epoxomicin markedly increased MCPIP1 expression. While MG-132 induces HeLa cell death, down-regulation of MCPIP1 expression by siRNA partially protects HeLa cells from MG-132 toxicity and restores Nuclear factor-κB (NF-κB) activity, inhibited by MG-132 treatment. Inversely, overexpression of MCPIP1 decreased constitutive activity of NF-κB and limited the survival of HeLa cells, as we have shown in the previous study. Interestingly, although MG-132 decreased the expression of IκBα and increased p65 phosphorylation, the inhibition of constitutive NF-κB activity was observed in MG-132-treated cells. Since the elevated constitutive activity of NF-κB is one of the mechanisms providing increased survival of cancer cells, including HeLa cells, we propose that death-promoting properties of MCPIP1 in MG-132-treated HeLa cells may, at least partially, derive from the negative effect on the constitutive NF-κB activity.

The ZmCLA4 gene in the qLA4-1 QTL controls leaf angle in maize (Zea mays L.).

PubMed

Zhang, J; Ku, L X; Han, Z P; Guo, S L; Liu, H J; Zhang, Z Z; Cao, L R; Cui, X J; Chen, Y H

2014-09-01

Maize architecture is a major contributing factor to their high level of productivity. Maize varieties with an erect-leaf-angle (LA) phenotype, which increases light harvesting for photosynthesis and grain-filling, have elevated grain yields. Although a large body of information is available on the map positions of quantitative trait loci (QTL) for LA, little is known about the molecular mechanism of these QTL. In this study, the ZmCLA4 gene, which is responsible for the qLA4-1 QTL associated with LA, was identified and isolated by fine mapping and positional cloning. The ZmCLA4 gene is an orthologue of LAZY1 in rice and Arabidopsis. Sequence analysis revealed two SNPs and two indel sites in ZmCLA4 between the D132 and D132-NIL inbred maize lines. Association analysis showed that C/T/mutation667 and CA/indel965 were strongly associated with LA. Subcellular localization verified the functions of a predicted transmembrane domain and a nuclear localization signal in ZmCLA4. Transgenic maize plants with a down-regulated ZmCLA4 RNAi construct and transgenic rice plants over-expressing ZmCLA4 confirmed that the ZmCLA4 gene located in the qLA4 QTL regulated LA. The allelic variants of ZmCLA4 in the D132 and D132-NIL lines exhibited significant differences in leaf angle. ZmCLA4 transcript accumulation was higher in D132-NIL than in D132 during all the developmental stages and was negatively correlated with LA. The gravitropic response was increased and cell shape and number at the leaf and stem junctions were altered in D132-NIL relative to D132. These findings suggest that ZmCLA4 plays a negative role in the control of maize LA through the alteration of mRNA accumulation, leading to altered shoot gravitropism and cell development. The cloning of the gene responsible for the qLA4-1 QTL provides information on the molecular mechanisms of LA in maize and an opportunity for the improvement of plant architecture with regard to LA through maize breeding. © The Author 2014

Electrochemical performances of co-substituted (La and Li) LiLa{sub x−y}Li{sub y}Ni{sub 1−x}O{sub 2} cathode materials for rechargeable lithium-ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohan, P.; Paruthimal Kalaignan, G., E-mail: pkalaignan@yahoo.com

2013-09-01

Graphical abstract: - Highlights: • LiLa{sub x−y}Li{sub x}Ni{sub 1−x}O{sub 2} powders were prepared by a sol–gel method at 600 °C for 10 h. • LiLa{sub x−y}Li{sub x}Ni{sub 1−x}O{sub 2} powder materials had well defined layer structure, and no impurities. • LiLa{sub 0.10}Li{sub 0.10}Ni{sub 0.80}O{sub 2} crystallite size was reduced compared with those of LiNiO{sub 2}. • Li/LiPF{sub 6}/LiLa{sub x−y}Li{sub x}Ni{sub 1−x}O{sub 2} cells were of high charge/discharge capacity, with columbic efficiency at 25 °C and 45 °C. • LiLa{sub 0.10}Li{sub 0.10}Ni{sub 0.80}O{sub 2} good cyclic stability, rate capability and better 45 °C. - Abstract: Co-substituted LiLa{sub x−y}Li{sub y}Ni{sub 1−x}O{sub 2}more » cathode materials were synthesized by sol–gel method using aqueous solutions of metal nitrates and tartaric acid as chelating agent at 600 °C for 10 h. The structure and electrochemical properties of the synthesized materials were characterized by using XRD, SEM, EDAX, TEM, cyclic voltammetry, charge/discharge and electrochemical impedance spectroscopy. XRD studies revealed a well defined layer structure and a linear variation of lattice parameters with the addition of lanthanum and lithium confirmed phase pure compounds in a rhombohedral structure. TEM and SEM analysis shows that LiLa{sub 0.10}Li{sub 0.10}Ni{sub 0.80}O{sub 2} has smaller particle size and regular morphological structure with narrow size distribution than those of LiNiO{sub 2}. Variations of dual mixing and hexagonal ordering with the substituted elements have enhanced the charge/discharge capacities at both room (25 °C) and elevated temperatures (45 °C), respectively. LiLa{sub 0.10}Li{sub 0.10}Ni{sub 0.80}O{sub 2} had high charge/discharge capacity, low irreversible capacity and better elevated temperature performance.« less

Influence of Fe doped on the magnetocaloric behavior of La_{{2}/{3}} Ca_{{1}/{3}} Mn1-x Fe x O3 compounds: a Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Alzate-Cardona, J. D.; Barco-Rios, H.; Restrepo-Parra, E.

2018-02-01

The magnetocaloric behavior of La{2/{3}} Ca{1/{3}} Mn1-x Fe x O3 for x  =  0.00, 0.02, 0.03, 0.05, 0.07, 0.08 and 0.10 under the influence of an external magnetic field was simulated and analyzed. Simulations were carried out using the Monte Carlo method and the classical Heisenberg model under the Metropolis algorithm. These mixed valence manganites are characterized by having three types of magnetic ions corresponding to Mn4+≤ft(S=\\frac{3}{2}\\right) , which are bonded with Ca2+ , and Mneg3+ and Mneg\\prime3+ (S=2) , related to La3+ . The Fe ions were randomly included, replacing Mn ions. With this model, the magnetic entropy change, Δ S , in an isothermal process was determined. -Δ Sm showed maximum peaks around the paramagnetic-ferromagnetic transition temperature, which depends on Fe doping. Relative cooling power was computed for different Fe concentrations varying the magnetic applied field. Our model and results show that the Fe doping decreases the magnetocaloric effect in the La{2/{3}} Ca{1/{3}} Mn1-x Fe x O3, making this a bad candidate for magnetic refrigeration. The strong dependence of the magnetocaloric behavior on Fe doping and the external magnetic field in La{2/{3}} Ca{1/{3}} Mn1-x Fe x O3 can boost these materials for the future technological applications.

LaAP2L1, a heterosis-associated AP2/EREBP transcription factor of Larix, increases organ size and final biomass by affecting cell proliferation in Arabidopsis.

PubMed

Li, Ai; Zhou, Yanan; Jin, Chuan; Song, Wenqin; Chen, Chengbin; Wang, Chunguo

2013-11-01

In Larix and in some crops, heterosis is prevalent and has been widely used in breeding to produce excellent varieties. However, the molecular basis of heterosis in Larix remains ambiguous. LaAP2L1, a member of the AP2/EREBP transcription factor family, has been suggested to be involved in heterosis in Larix hybrids. Here, the function and regulation of LaAP2L1 were further explored. Overexpression of LaAP2L1 led to markedly enlarged organs and heterosis-like traits in Arabidopsis. Fresh weight of leaves was almost twice as great as in vector controls. Likewise, seed yield of 35S::LaAP2L1 individual plants was >200% greater than that of control plants. The enlarged organs and heterosis-like traits displayed by 35S::LaAP2L1 plants were mainly due to enhanced cell proliferation and prolonged growth duration. At the molecular level, LaAP2L1 upregulated the expression of ANT, EBP1, and CycD3;1 and inhibited the expression of ARGOS in 35S::LaAP2L1 plants, suggesting an important molecular role of LaAP2L1 in regulating plant organ development. These findings provide new insights into the formation of heterosis in woody plants and suggest that LaAP2L1 has potential applications in breeding high-yielding crops and energy plants. In addition, 50 AP2/EREBP transcription factors, including LaAP2L1, in Larix were identified by transcriptome sequencing, and phylogenetic analysis was conducted. This provided information that will be important in further revealing the functions of these transcription factors.

Crystal Chemical Substitution at Ca and La Sites in CaLa4(SiO4)3O To Design the Composition Ca1- xM xLa4-xRE x(SiO4)3O for Nuclear Waste Immobilization and Its Influence on the Thermal Expansion Behavior.

PubMed

Ravikumar, Ramya; Gopal, Buvaneswari; Jena, Hrudananda

2018-06-04

The oxysilicate apatite host CaLa 4 (SiO 4 ) 3 O has been explored for immobilization of radioactive nuclides. Divalent ion, trivalent rare earth ion, and combined ionic substitutions in the silicate oxyapatite were carried out to optimize the simulated wasteform composition. The phases were characterized by powder X-ray diffraction, FT-IR, TGA, SEM-EDS, and HT-XRD techniques. The results revealed the effect of ionic substitutions on the structure and thermal expansion behavior. The investigation resulted in the formulation of simulated wasteforms such as La 3.4 Ce 0.1 Pr 0.1 Nd 0.1 Sm 0.1 Gd 0.1 Y 0.1 (SiO 4 ) 3 O (WF-1) and Ca 0.8 Sr 0.1 Pb 0.1 La 3.4 Ce 0.1 Pr 0.1 Nd 0.1 Sm 0.1 Gd 0.1 Y 0.1 (SiO 4 ) 3 O (WF-2). In comparison to the average axial thermal expansion coefficients of the hexagonal unit cell of the parent CaLa 4 (SiO 4 ) 3 O measured in the temperature range 298-1073 K (α' a = 9.74 × 10 -6 K -1 and α' c = 10.10 × 10 -6 K -1 ), rare earth ion substitution decreases the thermal expansion coefficients, as in the case of La 3.4 Ce 0.1 Pr 0.1 Nd 0.1 Sm 0.1 Gd 0.1 Y 0.1 (SiO 4 ) 3 O (α' a = 8.67 × 10 -6 K -1 and α' c = 7.94 × 10 -6 K -1 ). However, the phase Ca 0.8 Sr 0.1 Pb 0.1 La 3.4 Ce 0.1 Pr 0.1 Nd 0.1 Sm 0.1 Gd 0.1 Y 0.1 (SiO 4 ) 3 O shows an increase in the values of thermal expansion coefficients: α' a = 11.74 × 10 -6 K -1 and α' c = 11.70 × 10 -6 K -1 .

Evidence for a role of MRCK in mediating HeLa cell elongation induced by the C1 domain ligand HMI-1a3.

PubMed

Talman, Virpi; Gateva, Gergana; Ahti, Marja; Ekokoski, Elina; Lappalainen, Pekka; Tuominen, Raimo K

2014-05-13

Diacylglycerol (DAG) is a central mediator of signaling pathways that regulate cell proliferation, survival and apoptosis. Therefore, C1 domain, the DAG binding site within protein kinase C (PKC) and other DAG effector proteins, is considered a potential cancer drug target. Derivatives of 5-(hydroxymethyl)isophthalic acid are a novel group of C1 domain ligands with antiproliferative and differentiation-inducing effects. Our previous work showed that these isophthalate derivatives exhibit antiproliferative and elongation-inducing effects in HeLa human cervical cancer cells. In this study we further characterized the effects of bis(3-trifluoromethylbenzyl) 5-(hydroxymethyl)isophthalate (HMI-1a3) on HeLa cell proliferation and morphology. HMI-1a3-induced cell elongation was accompanied with loss of focal adhesions and actin stress fibers, and exposure to HMI-1a3 induced a prominent relocation of cofilin-1 into the nucleus regardless of cell phenotype. The antiproliferative and morphological responses to HMI-1a3 were not modified by pharmacological inhibition or activation of PKC, or by RNAi knock-down of specific PKC isoforms, suggesting that the effects of HMI-1a3 were not mediated by PKC. Genome-wide gene expression microarray and gene set enrichment analysis suggested that, among others, HMI-1a3 induces changes in small GTPase-mediated signaling pathways. Our experiments revealed that the isophthalates bind also to the C1 domains of β2-chimaerin, protein kinase D (PKD) and myotonic dystrophy kinase-related Cdc42-binding kinase (MRCK), which are potential mediators of small GTPase signaling and cytoskeletal reorganization. Pharmacological inhibition of MRCK, but not that of PKD attenuated HMI-1a3-induced cell elongation, suggesting that MRCK participates in mediating the effects of HMI-1a3 on HeLa cell morphology. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, characterization and study of magnetic, electrical and dielectric properties of La1-xDyxCo1-yFeyO3 nanoparticles prepared by wet chemical route

NASA Astrophysics Data System (ADS)

Choudhry, Qurshia; Azhar Khan, Muhammad; Nasar, Gulfam; Mahmood, Azhar; Shahid, Muhammad; Shakir, Imran; Farooq Warsi, Muhammad

2015-11-01

Dy3+ and Fe3+ co-doped LaCoO3 perovskite nanoparticles were prepared by chemical co-precipitation route. Structural elucidation was carried out by thermo gravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. The data of all these characterization techniques confirmed the orthorhombic phase with particles size in the range of 20-60 nm. The magnetic parameters, DC-resistivity and dielectric properties were measured for La1-xDyxCo1-yFeyO3 nanoparticles. The purpose of all these application studies was to evaluate the prepared materials for practical applications. The substitution of Dy3+ and Fe3+ with La3+ and Co3+ respectively greatly influenced the magnetic, DC-resistivity and dielectric parameters.

The electronic structure of Bi 2.0Sr 1.8La 0.3Ca 0.8Cu 2.1O 8+δ superconductors studied using ultraviolet and X-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Lindberg, P. A. P.; Shen, Z.-X.; Dessau, D. S.; Wells, B. O.; Borg, A.; Ellis, W.; Mitzi, D. B.; Lindau, I.; Spicer, W. E.; Kapitulnik, A.

1989-07-01

Photoemission measurements on single crystals of La-doped 2212 (Bi 2.0Sr 1.8La 0.3Ca 0.8Cu 2.1O 8+δ) superconductors were carried out utilizing both synchrotron and Al K α (1486.6 eV) radiation. A quantitative analysis of the photoemission data in comparison with similar data for the undoped 2212 material indicates that the La atoms preferentially occupy the Sr sites in the SrO layer next to the BiO plane. Evidence of alternation of the electronic environment of the Bi atoms is found in the Bi 5d core level spectra which show a shoulder at ≈ 1.2 eV higher binding energy, presumably due to the partial substitution of trivalent La ions (La 3+) for divalent Sr ions (Sr 2+). As for the undoped 2212 material, the photoemission spectra reveal a clear Fermi level cut-off at room temperature, single component O ls core level emission, and a Cu 2p satellite to main line intensity ratio of 0.4.

LaFe 0.9Ni 0.1O 3 perovskite catalyst with enhanced activity and coke-resistance for dry reforming of ethane

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Baohuai; Yan, Binhang; Yao, Siyu

In this work, a LaFe 0.9Ni 0.1O 3 perovskite catalyst was evaluated for dry reforming of ethane (DRE), with two conventional oxide supported Ni catalysts (Ni/La 2O 3 and NiFe/La 2O 3) being used as references. LaFe 0.9Ni 0.1O 3 showed the best activity and high coke-/sintering-resistance. TEM, TGA, and Raman characterizations confirmed that the deactivation of Ni/La 2O 3 was owing to the growth of Ni particles and the accumulation of coke, although the formation of La 2O 2CO 3 was able to remove part of the coke during the reaction. The introduction of Fe-related species inhibited the cokemore » formation while decreased the activity due to the loss of active sites. A portion of Ni ions in the perovskite lattice could be reduced to form highly dispersed and stable Ni nanoparticles on the surface during the reaction and oxygen vacancies were left in the perovskite lattice. Pulse reactor studies revealed that the oxygen vacancies in the perovskite could facilitate the activation and dissociation of CO 2 to form CO and reactive oxygen species. Additionally, C 2H 6 was activated with the assistance of oxygen from the surface or subsurface of LaFe 0.9Ni 0.1O 3 to form CO, rather than directly dissociated to surface carbon species as observed over Ni/La 2O 3.« less

LaFe 0.9Ni 0.1O 3 perovskite catalyst with enhanced activity and coke-resistance for dry reforming of ethane

DOE PAGES

Zhao, Baohuai; Yan, Binhang; Yao, Siyu; ...

2017-12-29

In this work, a LaFe 0.9Ni 0.1O 3 perovskite catalyst was evaluated for dry reforming of ethane (DRE), with two conventional oxide supported Ni catalysts (Ni/La 2O 3 and NiFe/La 2O 3) being used as references. LaFe 0.9Ni 0.1O 3 showed the best activity and high coke-/sintering-resistance. TEM, TGA, and Raman characterizations confirmed that the deactivation of Ni/La 2O 3 was owing to the growth of Ni particles and the accumulation of coke, although the formation of La 2O 2CO 3 was able to remove part of the coke during the reaction. The introduction of Fe-related species inhibited the cokemore » formation while decreased the activity due to the loss of active sites. A portion of Ni ions in the perovskite lattice could be reduced to form highly dispersed and stable Ni nanoparticles on the surface during the reaction and oxygen vacancies were left in the perovskite lattice. Pulse reactor studies revealed that the oxygen vacancies in the perovskite could facilitate the activation and dissociation of CO 2 to form CO and reactive oxygen species. Additionally, C 2H 6 was activated with the assistance of oxygen from the surface or subsurface of LaFe 0.9Ni 0.1O 3 to form CO, rather than directly dissociated to surface carbon species as observed over Ni/La 2O 3.« less

Oxygen vacancies induced switchable and nonswitchable photovoltaic effects in Ag/Bi{sub 0.9}La{sub 0.1}FeO{sub 3} /La{sub 0.7}Sr{sub 0.3}MnO{sub 3} sandwiched capacitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, R. L., E-mail: gaorongli2008@163.com, E-mail: jrsun@iphy.ac.cn; Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Science, Beijing 100190; Yang, H. W.

2014-01-20

The short circuit photocurrent (I{sub sc}) was found to be strongly dependent on the oxygen vacancies (V{sub Os}) distribution in Ag/Bi{sub 0.9}La{sub 0.1}FeO{sub 3}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3} heterostructures. In order to manipulate the V{sub Os} accumulated at either the Ag/Bi{sub 0.9}La{sub 0.1}FeO{sub 3} or the Bi{sub 0.9}La{sub 0.1}FeO{sub 3}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3} interface by pulse voltages, switchable or nonswitchable photocurrent can be observed without or with changing the polarization direction. The sign of photocurrent could be independent of the direction of polarization when the variation of diffusion current and the modulation of the Schottky barrier at the Ag/Bi{sub 0.9}La{sub 0.1}FeO{submore » 3} interface induced by oxygen vacancies are large enough to offset those induced by polarization. Our work provides deep insights into the nature of photovoltaic effects in ferroelectric films, and will facilitate the advanced design of switchable devices combining spintronic, electronic, and optical functionalities.« less

Strain-relaxation and critical thickness of epitaxial La 1.85Sr 0.15CuO 4 films

DOE PAGES

Meyer, Tricia L; Jiang, Lu; Park, Sungkyun; ...

2015-12-08

We report the thickness-dependent strain-relaxation behavior and the associated impacts upon the superconductivity in epitaxial La 1.85Sr 0.15CuO 4 films grown on different substrates, which provide a range of strain. We have found that the critical thickness for the onset of superconductivity in La 1.85Sr 0.15CuO 4 films is associated with the finite thickness effect and epitaxial strain. In particular, thin films with tensile strain greater than ~0.25% revealed no superconductivity. We attribute this phenomenon to the inherent formation of oxygen vacancies that can be minimized via strain relaxation.

Magnetism in La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Co{sub x}O{sub 3} (0 ≤ x ≤ 1)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Ashutosh, E-mail: ashutosh.pph13@iitp.ac.in; Sharma, Himanshu; Tomy, C. V.

2016-05-23

We study the structural and magnetic properties of La{sub 0.7}Sr{sub 0.3}Mn{sub 1-x}Co{sub x}O{sub 3} (0 ≤ x ≤ 1). Rietveld refinement of X-ray Diffraction (XRD) pattern suggests phase purity of the polycrystalline samples with R-3c space group. Interplay of Ferromagnetic (FM) and Antiferromagnetic (AFM) interaction upon Co substitution at Mn site in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} is evident from magnetic measurements. There is an optimal cobalt substitution at which the coercive field is maximum.

Microstructure and improved magnetocaloric properties: LaFeSi/LaAl magnets prepared by spark plasma sintering technique

NASA Astrophysics Data System (ADS)

Fan, W. B.; Hou, Y. H.; Ge, X. J.; Huang, Y. L.; Luo, J. M.; Zhong, Z. C.

2018-03-01

Bulk LaFeSi magnets with the addition of LaAl alloy showing excellent performance were prepared by the spark plasma sintering (SPS) technique. The effects of heat treatment and various amounts of LaAl on the microstructure and magnetocaloric properties were investigated in details. It was found that appropriate amounts of LaAl can promote the peritectic reaction, and LaFeSi magnets with a high 1:13 phase amount can be obtained. Due to the unfavorable effects of Al in the peritectic reaction, excess addition of LaAl alloy was not beneficial to the formation of the 1:13 phase. The addition of 5 wt.% LaAl was most favorable to the formation of the 1:13 phase. Furthermore, heat treatment had important effects on the formation of the 1:13 phase and magnetocaloric performance. For SPSed LaFeSi magnets with 5 wt.% LaAl, the maximum values of magnetic entropy change (-ΔS M)max and refrigerating capacity (RC) are 18.07 J · kg-1 · K-1 and 327.55 J · kg-1 under the field changes of 0-5 T, respectively. The variation of Curie temperature (T C) depended on the joint effects from the antiferromagnetic interaction between Fe-Al atoms and the ferromagnetic interaction between Fe-Fe atoms.

Neutron and electron diffraction studies of La(Zn1/2Ti1/2)O3 perovskite.

PubMed

Ubic, Rick; Hu, Yi; Abrahams, Isaac

2006-08-01

The crystallography and microwave dielectric properties of La(Zn(1/2)Ti(1/2))O(3) (LZT) ceramics prepared via the mixed-oxide route were investigated in this study. While samples were largely single phase, small amounts of ZnO impurity were detected in sintered pellets. Observed reflections in electron and neutron diffraction patterns indicate that the symmetry of LZT is P2(1)/n. The B site is ordered on {110} or pseudocubic {111}, but the presence of the pseudocubic 1/2(111) reflection is in itself insufficient to indicate the existence of such order. Rietveld refinements of the neutron diffraction data yield an excellent fit for such a model. The structure is highly twinned, with variants related through common {211} composition planes and 90 degrees rotations about <011>. The microwave dielectric properties measured were epsilon(r) = 34, Qf = 36,090 and tau(f) = -70 MK(-1).

Channelling study of La1-xSrxCoO3 films on different substrates

NASA Astrophysics Data System (ADS)

Szilágyi, E.; Kótai, E.; Rata, D.; Németh, Z.; Vankó, G.

2014-08-01

The cobalt oxide system LaCoO3 and its Sr-doped child compounds have been intensively studied for decades due to their intriguing magnetic and electronic properties. Preparing thin La1-xSrxCoO3 (LSCO) films on different substrates allows for studies with a new type of perturbation, as the films are subject to substrate-dependent epitaxial strain. By choosing a proper substrate for a thin film grow, not only compressing but also tensile strain can be applied. The consequences for the fundamental physical properties are dramatic: while compressed films are metallic, as the bulk material, films under tensile strain become insulating. The goal of this work is to determine the strain tensor in LSCO films prepared on LaAlO3 and SrTiO3 substrates by pulsed laser deposition using RBS/channelling methods. Apart from the composition and defect structure of the samples, the depth dependence of the strain tensor, the cell parameters, and the volume of the unit cell are also determined. Asymmetric behaviour of the strained cell parameters is found on both substrates. This asymmetry is rather weak in the case of LSCO film grown on LaAlO3, while stronger on SrTiO3 substrate. The strain is more effective at the interface, some relaxation can be observed near to the surface.

Pilot Comments for High Speed Research Cycle 3 Simulations Study (LaRC.1)

NASA Technical Reports Server (NTRS)

Bailey, Melvin L. (Editor); Jackson, E. Bruce (Technical Monitor)

2000-01-01

This is a compilation of pilot comments from the Boeing High Speed Research Aircraft, Cycle 3 Simulation Study (LaRC.1) conducted from January to March 1997 at NASA Langley Research Center. This simulation study was conducted using the Visual Motion Simulator. The comments are direct tape transcriptions and have been edited for spelling only.

Determination de la Distribution Granulometrique des Particules par la Mesure de la Transmission d’un Aerosol Sedimentant (Aerosol Size Distribution Using the Extinction-Sedimentation Inversion Technique),

DTIC Science & Technology

1982-11-01

est la longueur du chemin optique. La fonction K(xn, n) peut Stre evaluee 1 l’aide de la theorie de Mie. Elle est du type oscillant et tend vers 2...Directeur, Division de l1informatlque - Directeur, Division de la Propulsion 10 - Bibliotheque - M. G. Roy ( auteur ) - Dr R. Lavertu - Dr B.T.N

Optical and transport properties of LaTi{sub 1−x}M{sub x}(O,N){sub 3±δ} (x=0; 0.1, M=Nb{sup 5+}, W{sup 6+}) thin films prepared by plasma ammonolysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maegli, Alexandra E.; Sagarna, Leyre; Populoh, Sascha

2014-03-15

Oxynitride thin films of composition LaTi{sub 1−x}M{sub x}(O,N){sub 3±δ} with x=0; 0.1 and M=Nb{sup 5+}, W{sup 6+} were prepared by nitridation via microwave-induced plasma (MIP) ammonolysis, which allowed keeping the nitridation time short (16 min). The higher possible oxidation states of the B-site substituents (Nb{sup 5+}, W{sup 6+}) with respect to Ti{sup 4+} caused higher N content for LaTi{sub 0.9}Nb{sub 0.1}(O,N){sub 3±δ} and LaTi{sub 0.9}W{sub 0.1}(O,N){sub 3±δ} compared to LaTiO{sub 2}N due to charge-compensation. XPS O 1s and N 1s core level and valence band spectra evidenced for increasing N content in the order LaTiO{sub 2}N

Co-encapsulation of chrysophsin-1 and epirubicin in PEGylated liposomes circumvents multidrug resistance in HeLa cells.

PubMed

Lo, Yu-Li; Tu, Wei-Chen

2015-12-05

Chrysophsin-1, an amphipathic alpha-helical antimicrobial peptide, is isolated from the gills of the red sea bream and possesses different structure and mechanism(s) in comparison with traditional multidrug resistance (MDR) modulators. For the purpose of reducing off-target normal cell toxicity, it is rational to incorporate chrysophsin-1 and epirubicin in a PEGylated liposomal formulation. In the present study, we report a multifunctional liposomes with epirubicin as an antineoplastic agent and an apoptosis inducer, as well as chrysophsin-1 as a MDR transporter inhibitor and an apoptosis modulator in human cervical cancer HeLa cells. Co-incubation of HeLa cells with PEGylated liposomal formulation of epirubicin and chrysophsin-1 resulted in a significant increase in the cytotoxicity of epirubicin. The liposomal formulations of epirubicin and/or chrysophsin-1 were shown to considerably improve the intracellular H2O2 and O2(-) levels of HeLa cells. Furthermore, these treatments were found to extensively reduce mRNA expression levels of MDR1, MRP1, and MRP2. The addition of chrysophsin-1 in liposomes was demonstrated to substantially enhance the intracellular accumulation of epirubicin in HeLa cells. Moreover, the PEGylated liposomes of epirubicin and chrysophsin-1 were also found to significantly increase the mRNA expressions of p53, Bax, and Bcl-2. The ratio of Bax to Bcl-2 was noticeably amplified in the presence of these formulations. Apoptosis induction was also validated by chromatin condensation, a reduction in mitochondrial membrane potential, the increased sub-G1 phase of cell cycle, and more populations of apoptosis using annexin V/PI assay. These formulations were verified to increase the activity and mRNA expression levels of caspase-9 and caspases-3. Collectively, our findings provide the first evidence that cotreatment with free or liposomal chrysophsin-1 and epirubicin leads to cell death in human cervical cancer cells through the ROS

Structural, magnetic, and superconducting properties of pulsed-laser-deposition-grown La 1.85 Sr 0.15 CuO 4 / La 2 / 3 Ca 1 / 3 MnO 3 superlattices on (001)-oriented LaSrAlO 4 substrates

DOE PAGES

Das, S.; Sen, K.; Marozau, I.; ...

2014-03-12

Epimore » taxial La 1.85 Sr 0.15 CuO 4 / La 2 / 3 Ca 1 / 3 MnO 3 (LSCO/LCMO) superlattices (SL) on (001)- oriented LaSrAlO 4 substrates have been grown with pulsed laser deposition (PLD) technique. Their structural, magnetic and superconducting properties have been determined with in-situ reflection high energy electron diffraction (RHEED), x-ray diffraction, specular neutron reflectometry, scanning transmission electron microscopy (STEM), electric transport, and magnetization measurements. We find that despite the large mismatch between the in-plane lattice parameters of LSCO (a = 0.3779 nm) and LCMO (a = 0.387 nm) these superlattices can be grown epitaxially and with a high crystalline quality. While the first LSCO layer remains clamped to the LSAO substrate, a sizeable strain relaxation occurs already in the first LCMO layer. The following LSCO and LCMO layers adopt a nearly balanced state in which the tensile and compressive strain effects yield alternating in-plane lattice parameters with an almost constant average value. No major defects are observed in the LSCO layers, while a significant number of vertical antiphase boundaries are found in the LCMO layers. The LSCO layers remain superconducting with a relatively high superconducting onset temperature of T c onset ≈ 36 K. The macroscopic superconducting response is also evident in the magnetization data due to a weak diamagnetic signal below 10 K for H ∥ ab and a sizeable paramagnetic shift for H ∥ c that can be explained in terms of a vortex-pinning-induced flux compression. The LCMO layers maintain a strongly ferromagnetic state with a Curie temperature of T Curie ≈ 190 K and a large low-temperature saturation moment of about 3.5 (1) μ B. These results suggest that the LSCO/LCMO superlattices can be used to study the interaction between the antagonistic ferromagnetic and superconducting orders and, in combination with previous studies on YBCO/LCMO superlattices, may allow one to identify the

Structural, magnetic, and superconducting properties of pulsed-laser-deposition-grown La 1.85 Sr 0.15 CuO 4 / La 2 / 3 Ca 1 / 3 MnO 3 superlattices on (001)-oriented LaSrAlO 4 substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Das, S.; Sen, K.; Marozau, I.

Epimore » taxial La 1.85 Sr 0.15 CuO 4 / La 2 / 3 Ca 1 / 3 MnO 3 (LSCO/LCMO) superlattices (SL) on (001)- oriented LaSrAlO 4 substrates have been grown with pulsed laser deposition (PLD) technique. Their structural, magnetic and superconducting properties have been determined with in-situ reflection high energy electron diffraction (RHEED), x-ray diffraction, specular neutron reflectometry, scanning transmission electron microscopy (STEM), electric transport, and magnetization measurements. We find that despite the large mismatch between the in-plane lattice parameters of LSCO (a = 0.3779 nm) and LCMO (a = 0.387 nm) these superlattices can be grown epitaxially and with a high crystalline quality. While the first LSCO layer remains clamped to the LSAO substrate, a sizeable strain relaxation occurs already in the first LCMO layer. The following LSCO and LCMO layers adopt a nearly balanced state in which the tensile and compressive strain effects yield alternating in-plane lattice parameters with an almost constant average value. No major defects are observed in the LSCO layers, while a significant number of vertical antiphase boundaries are found in the LCMO layers. The LSCO layers remain superconducting with a relatively high superconducting onset temperature of T c onset ≈ 36 K. The macroscopic superconducting response is also evident in the magnetization data due to a weak diamagnetic signal below 10 K for H ∥ ab and a sizeable paramagnetic shift for H ∥ c that can be explained in terms of a vortex-pinning-induced flux compression. The LCMO layers maintain a strongly ferromagnetic state with a Curie temperature of T Curie ≈ 190 K and a large low-temperature saturation moment of about 3.5 (1) μ B. These results suggest that the LSCO/LCMO superlattices can be used to study the interaction between the antagonistic ferromagnetic and superconducting orders and, in combination with previous studies on YBCO/LCMO superlattices, may allow one to identify the

Tunable thermodynamic activity of La x Sr1-x Mn y Al1-y O3-δ (0 ≤ x ≤ 1, 0 ≤ y ≤ 1) perovskites for solar thermochemical fuel synthesis.

PubMed

Ezbiri, M; Takacs, M; Theiler, D; Michalsky, R; Steinfeld, A

2017-02-28

Nonstoichiometric metal oxides with variable valence are attractive redox materials for thermochemical and electrochemical fuel processing. To guide the design of advanced redox materials for solar-driven splitting of CO 2 and/or H 2 O to produce CO and/or H 2 (syngas), we investigate the equilibrium thermodynamics of the La x Sr 1- x Mn y Al 1- y O 3- δ perovskite family (0 ≤ x ≤ 1, 0 ≤ y ≤ 1) and La 0.6 Ca 0.4 Mn 0.8 Al 0.2 O 3- δ , and compare them to those of CeO 2 as the baseline. Oxygen nonstoichiometry measurements from 1573 to 1773 K and from 0.206 to 180 mbar O 2 show a tunable reduction extent, increasing with increasing Sr content. Maximal nonstoichiometry of 0.32 is established with La 0.2 Sr 0.8 Mn 0.8 Al 0.2 O 3- δ at 1773 K and 2.37 mbar O 2 . As a trend, we find that oxygen capacities are most sensitive to the A-cation composition. Partial molar enthalpy, entropy and Gibbs free energy changes for oxide reduction are extracted from the experimental data using defect models for Mn 4+ /Mn 3+ and Mn 3+ /Mn 2+ redox couples. We find that perovskites exhibit typically decreasing enthalpy changes with increasing nonstoichiometries. This desirable characteristic is most pronounced by La 0.6 Sr 0.4 Mn 0.4 Al 0.6 O 3- δ , rendering it attractive for CO 2 and H 2 O splitting. Generally, perovskites show lower enthalpy and entropy changes than ceria, resulting in more favorable reduction but less favorable oxidation equilibria. The energy penalties due to larger temperature swings and excess oxidants are discussed in particular. Using electronic structure theory, we conclude with a practical methodology estimating thermodynamic activity to rationally design perovskites with variable stoichiometry and valence.

Structural and electrochemical properties of annealed La1-xYxNi3.55Mno.4Alo.3Coo.75 hydrogen storage alloys.

PubMed

Du, Yulei; Li, Wei

2011-06-01

The effects of the annealing and partial substitution of Y for La on the structural and electrochemical properties of La1-xYxNi3.55Mno.4Alo.3Cro.75 (x = 0, 0.1 and 0.2) alloys were reported in the present work. The single-phased CaCu5-type structure was retained after La was partially substituted by Y. However, the increase of Y content leads to decrease of the lattice parameters and the unit-cell volume. The annealed Lao.9Yo.1Ni3.55Mno.4Alo.3Coo.75 alloys shows typical isometric microstructure, indicating that the composition segregation is improved by annealing. Y substitution for La in the alloys is effective to improve the electrochemical properties at both room temperature and high temperature. A critical substitution content of Y is found at x = 0.1. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Zac1, an Sp1-like protein, regulates human p21{sup WAF1/Cip1} gene expression in HeLa cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Pei-Yao; Hsieh, Tsai-Yuan; Liu, Shu-Ting

2011-12-10

Zac1 functions as both a transcription factor and a transcriptional cofactor for p53, nuclear receptors (NRs) and NR coactivators. Zac1 might also act as a transcriptional repressor via the recruitment of histone deacetylase 1 (HDAC1). The ability of Zac1 to interact directly with GC-specific elements indicates that Zac1 possibly binds to Sp1-responsive elements. In the present study, our data show that Zac1 is able to interact directly with the Sp1-responsive element in the p21{sup WAF1/Cip1} gene promoter and enhance the transactivation activity of Sp1 through direct physical interaction. Our data further demonstrate that Zac1 might enhance Sp1-specific promoter activity bymore » interacting with the Sp1-responsive element, affecting the transactivation activity of Sp1 via a protein-protein interaction, or competing the HDAC1 protein away from the pre-existing Sp1/HDAC1 complex. Finally, the synergistic regulation of p21{sup WAF1/Cip1} gene expression by Zac1 and Sp1 is mediated by endogenous p53 protein and p53-responsive elements in HeLa cells. Our work suggests that Zac1 might serve as an Sp1-like protein that directly interacts with the Sp1-responsive element to oligomerize with and/or to coactivate Sp1.« less

Modulation of the cyclin-dependent kinase inhibitor p21(WAF1/Cip1) gene by Zac1 through the antagonistic regulators p53 and histone deacetylase 1 in HeLa Cells.

PubMed

Liu, Pei-Yao; Chan, James Yi-Hsin; Lin, Hsiu-Chen; Wang, Sung-Ling; Liu, Shu-Ting; Ho, Ching-Liang; Chang, Li-Chien; Huang, Shih-Ming

2008-07-01

Zac1 is a novel seven-zinc finger protein which possesses the ability to bind specifically to GC-rich DNA elements. Zac1 not only promotes apoptosis and cell cycle arrest but also acts as a transcriptional cofactor for p53 and a number of nuclear receptors. Our previous study indicated that the enhancement of p53 activity by Zac1 is much more pronounced in HeLa cells compared with other cell lines tested. This phenomenon might be due to the coactivator effect of Zac1 on p53 and the ability of Zac1 to reverse E6 inhibition of p53. In the present study, we showed that Zac1 acted synergistically with either p53 or a histone deacetylase inhibitor, trichostatin A, to enhance p21(WAF1/Cip1) promoter activity. We showed that Zac1 physically interacted with some nuclear receptor corepressors such as histone deacetylase 1 (HDAC1) and mSin3a, and the induction of p21(WAF1/Cip1) gene and protein by Zac1 was suppressed by either overexpressing HDAC1 or its deacetylase-dead mutant. In addition, our data suggest that trichostatin A-induced p21(WAF1/Cip1) protein expression might be mediated through a p53-independent and HDAC deacetylase-independent pathway. Taken together, our data suggest that Zac1 might be involved in regulating the p21(WAF1/Cip1) gene and protein expression through its protein-protein interaction with p53 and HDAC1 in HeLa cells.

Optical evidence for the spin-state disorder in LaCo1-x Rh x O3

NASA Astrophysics Data System (ADS)

Terasaki, Ichiro; Asai, Shinichiro; Taniguchi, Hiroki; Okazaki, Ryuji; Yasui, Yukio; Ikemoto, Yuka; Moriwaki, Taro

2017-06-01

We have measured the infrared reflectivity of single-crystalline samples of LaCo1-x Rh x O3 (x  =  0, 0.05 and 0.10) from 10 to 300 K from 0.05 to 0.15 eV. We find that the optical phonons of the Co-O stretching mode depend on temperature and the Rh content. Analysis with three Lorentz oscillators reveals that the spin state of Co3+ in LaCo1-x Rh x O3 can be understood in terms of a solid solution of low-spin- and high-spin-state Co3+ ions, and the substituted Rh ion retains some fraction of the high-spin Co3+ ions down to low temperature.

Spin-state transitions and magnetic polaron in lightly doped La1-xSrxCoO3.

NASA Astrophysics Data System (ADS)

Podlesnyak, A.; Haverkort, M. W.; Conder, K.; Pomyakushina, E.; Khomskii, Daniel

2007-03-01

Using the inelastic neutron scattering (INS) technique, we identified the energy levels of the thermally excited states of Co^3+ ions in both LaCoO3 and La0.998Sr0.002CoO3. In LaCoO3 an excitation at ˜0.6 meV appears at T>30K, whose intensity follows the bulk magnetization. Within a model including crystal field interaction and spin-orbit coupling we interpret this excitation as originating from a transition between thermally excited states located about 120 K above the ground state. Since the g-factor obtained from the field dependence of the INS is g˜ 3, we interpret this state as a high-spin state of Co^3+ . The lightly doped material x˜0:002 exhibits paramagnetic properties at low temperatures. An INS peak at energy transfer ˜0.75 meV was observed in it already at T = 1:5 K. We propose that the holes introduced in the LS state of LaCoO3 by doping are extended over the neighboring Co sites, forming thus magnetic polaron and transforming all the involved Co ions (e.g. 6 of them) to the high-spin state. Similarly to LaCoO3, we interpret the INS transition at 0.75 meV as that on these high-spin Co^3+ ions.

Effets Seebeck et Nernst dans les cuprates: Etude de la reconstruction de la surface de Fermi sous champ magnetique intense

NASA Astrophysics Data System (ADS)

Laliberte, Francis

2010-06-01

Ce memoire presente des mesures de transport thermoelectrique, les effets Seebeck et Nernst, dans une serie d'echantillons de supraconducteurs a haute temperature critique. Des resultats obtenus recemment au Laboratoire National des Champs Magnetiques Intenses a Grenoble sur La1.7Eu0.2Sr0.1 CuO4, La1.675Eu0.2Sr0.125CuO 4, La1.64Eu0.2Sr0.16CuO4, La1.74Eu0.1Sr0.16CuO4 et La 1.4Nd0.4Sr0.2CuO4 sont analyses. Une attention particuliere est accordee aux equations de la theorie semi-classique du transport et leur validite est verifiee. La procedure experimentale et les materiaux utilises pour concevoir les montages de mesures sont expliques en detail. Enfin, un chapitre est dedie a l'explication et l'interpretation des resultats de transport thermoelectrique sur YBa2Cu3O6+delta publies au cours de l'hiver 2010 dans les revues Nature et Physical Review Letters. Les donnees d'effet Seebeck dans les echantillons de La 1.8-x,Eu0.2SrxCuO 4, ou un changement de signe est observe, permettent de conclure a la presence d'une poche d'electrons dans la surface de Fermi qui domine le transport a basse temperature dans la region sous-dopee du diagramme de phase. Cette conclusion est similaire a celle obtenue par des mesures d'effet Hall dans YBa 2Cu3O6+delta et elle cadre bien dans un scenario de reconstruction de la surface de Fermi. Les donnees d'effet Nernst recueillies indiquent que la contribution des fluctuations supraconductrices est limitee a un modeste intervalle de temperature au-dessus de la temperature critique.

Interrelation of transport properties, defect structure and spin state of Ni3+ in La1.2Sr0.8Ni0.9Fe0.1O4+δ

NASA Astrophysics Data System (ADS)

Gilev, A. R.; Kiselev, E. A.; Zakharov, D. M.; Cherepanov, V. A.

2017-10-01

The total conductivity, Seebeck coefficient and oxygen non-stoichiometry for La1.2Sr0.8Ni0.9Fe0.1O4+δ have been measured vs temperature and oxygen partial pressure P(O2). The measurements were carried out at 800, 850, 900 and 950 °C within the P(O2) range of 10-5-0.21 atm. La1.2Sr0.8Ni0.9Fe0.1O4+δ was shown to be oxygen deficient in all temperature and P(O2) ranges studied. The calculated values of the partial molar enthalpy of oxygen depend very slightly on oxygen content (δ), indicating that La1.2Sr0.8Ni0.9Fe0.1O4+δ with the oxygen deficiency can be considered an ideal solution. The model of point defect equilibria in La1.2Sr0.8Ni0.9Fe0.1O4+δ has been proposed and fitted to experimental dependencies. Subsequent joint analysis of the defect structure and transport properties revealed that electron holes can coexist in both localized and quasi-delocalized states in the oxide: the former corresponded to high-spin state Ni3+ and the latter - to low-spin state Ni3+. The mobilities of localized electron holes were shown to be significantly lower in comparison to quasi-delocalized ones. The behavior of localized electron holes was explained in terms of a small polaron conduction mechanism; in contrast, quasi-delocalized electron holes were described in terms of a band conduction approach. The small polaron conduction mechanism was shown to be predominant in the Sr- and Fe-co-doped lanthanum nickelate.

Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca 1 - x La x FeAs 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Chang-Jong; Birol, Turan; Kotliar, Gabriel

The recently discovered high-T c superconductor Ca 1-xLa xFeAs 2 is a unique compound not just because of its low-symmetry crystal structure but also because of its electronic structure, which hosts Dirac-like metallic bands resulting from (spacer) zigzag As chains. We present a comprehensive first-principles theoretical study of the electronic and crystal structures of Ca 1-xLa xFeAs 2. After discussing the connection between the crystal structure of the 112 family, which Ca 1-xLa xFeAs 2 is a member of, with the other known structures of Fe pnictide superconductors, we check the thermodynamic phase stability of CaFeAs 2, and similar hyphotheticalmore » compounds SrFeAs 2 and BaFeAs 2 which, we find, are slightly higher in energy. We calculate the optical conductivity of Ca 1-xLa xFeAs 2 using the DFT+DMFT method and predict a large in-plane resistivity anisotropy in the normal phase, which does not originate from electronic nematicity, but is enhanced by the electronic correlations. In particular, we predict a 0.34 eV peak in the yy component of the optical conductivity of the 30% La-doped compound, which corresponds to coherent interband transitions within a fast-dispersing band arising from the zigzag As chains, which are unique to this compound. We also study the Landau free energy for Ca 1-xLa xFeAs 2 including the order parameter relevant for the nematic transition and find that the free energy does not have any extra terms that could induce ferro-orbital order. This explains why the presence of As chains does not broaden the nematic transition in Ca 1-xLa xFeAs 2.« less

Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca 1 - x La x FeAs 2

DOE PAGES

Kang, Chang-Jong; Birol, Turan; Kotliar, Gabriel

2017-01-17

The recently discovered high-T c superconductor Ca 1-xLa xFeAs 2 is a unique compound not just because of its low-symmetry crystal structure but also because of its electronic structure, which hosts Dirac-like metallic bands resulting from (spacer) zigzag As chains. We present a comprehensive first-principles theoretical study of the electronic and crystal structures of Ca 1-xLa xFeAs 2. After discussing the connection between the crystal structure of the 112 family, which Ca 1-xLa xFeAs 2 is a member of, with the other known structures of Fe pnictide superconductors, we check the thermodynamic phase stability of CaFeAs 2, and similar hyphotheticalmore » compounds SrFeAs 2 and BaFeAs 2 which, we find, are slightly higher in energy. We calculate the optical conductivity of Ca 1-xLa xFeAs 2 using the DFT+DMFT method and predict a large in-plane resistivity anisotropy in the normal phase, which does not originate from electronic nematicity, but is enhanced by the electronic correlations. In particular, we predict a 0.34 eV peak in the yy component of the optical conductivity of the 30% La-doped compound, which corresponds to coherent interband transitions within a fast-dispersing band arising from the zigzag As chains, which are unique to this compound. We also study the Landau free energy for Ca 1-xLa xFeAs 2 including the order parameter relevant for the nematic transition and find that the free energy does not have any extra terms that could induce ferro-orbital order. This explains why the presence of As chains does not broaden the nematic transition in Ca 1-xLa xFeAs 2.« less

A systems biology analysis of the changes in gene expression via silencing of HPV-18 E1 expression in HeLa cells.

PubMed

Castillo, Andres; Wang, Lu; Koriyama, Chihaya; Eizuru, Yoshito; Jordan, King; Akiba, Suminori

2014-10-01

Previous studies have reported the detection of a truncated E1 mRNA generated from HPV-18 in HeLa cells. Although it is unclear whether a truncated E1 protein could function as a replicative helicase for viral replication, it would still retain binding sites for potential interactions with different host cell proteins. Furthermore, in this study, we found evidence in support of expression of full-length HPV-18 E1 mRNA in HeLa cells. To determine whether interactions between E1 and cellular proteins play an important role in cellular processes other than viral replication, genome-wide expression profiles of HPV-18 positive HeLa cells were compared before and after the siRNA knockdown of E1 expression. Differential expression and gene set enrichment analysis uncovered four functionally related sets of genes implicated in host defence mechanisms against viral infection. These included the toll-like receptor, interferon and apoptosis pathways, along with the antiviral interferon-stimulated gene set. In addition, we found that the transcriptional coactivator E1A-binding protein p300 (EP300) was downregulated, which is interesting given that EP300 is thought to be required for the transcription of HPV-18 genes in HeLa cells. The observed changes in gene expression produced via the silencing of HPV-18 E1 expression in HeLa cells indicate that in addition to its well-known role in viral replication, the E1 protein may also play an important role in mitigating the host's ability to defend against viral infection.

Antimicrobial activity of Lactobacillus strains of chicken origin against bacterial pathogenss.

PubMed

Dec, Marta; Puchalski, Andrzej; Nowaczek, Anna; Wernicki, Andrzej

2016-03-01

This study was conducted to identify and evaluate the antimicrobial activity of some Lactobacillus isolates of chicken origin. Among 90 isolates 14 Lactobacillus species were distinguished using MALDI-TOF mass spectrometry and 16S-ARDRA. The dominant species was L. salivarius (34.4%), followed by L. johnsonii (23.3%), L. crispatus (13.3%) and L. reuteri (11.1%). All lactobacilli were screened for antimicrobial activity against wild-type strains of Salmonella enterica, Escherichia coli, and Clostridium perfringens. Results from the agar slab method showed that all Lactobacillus isolates were able to produce active compounds on solid media with antagonistic properties against these pathogens. The highest sensitivity to lactobacilli was observed in C. perfringens strains, and the lowest in E. coli. Lactobacillus salivarius exhibited particularly strong antagonism towards all of the indicator bacteria. Strains of L. ingluviei and L. johnsonii and one strain of L. salivarius (10d) selectively inhibited the growth of C. perfringens. No antimicrobial activity of many Lactobacillus isolates was observed when cell-free culture supernatant was used in a well diffusion assay. All Lactobacillus isolates exhibited the ability to produce H2O2 and proved to be hydrophobic (excluding one of L. salivarius). [Int Microbiol 19(1):57-67 (2016)]. Copyright© by the Spanish Society for Microbiology and Institute for Catalan Studies.

33 CFR 80.835 - Point Au Fer, LA to Calcasieu Pass, LA.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Point Au Fer, LA to Calcasieu... SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Eighth District § 80.835 Point Au Fer, LA to Calcasieu Pass, LA. (a) A line drawn from Point Au Fer to Atchafalaya Channel Light 34, to Point...

33 CFR 80.835 - Point Au Fer, LA to Calcasieu Pass, LA.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Point Au Fer, LA to Calcasieu... SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Eighth District § 80.835 Point Au Fer, LA to Calcasieu Pass, LA. (a) A line drawn from Point Au Fer to Atchafalaya Channel Light 34, to Point...

Spin-State Transition in La1-xSrxCoO3 Single Crystals

NASA Astrophysics Data System (ADS)

Bhardwaj, S.; Prabhakaran, D.; Awasthi, A. M.

2011-07-01

We present a study of the thermal conductivity (κ), specific heat (Cp) and Raman spectra of La1-xSrxCoO3 (x = 0,0.1) single crystals. Both the specimens have low thermal conductivity and board Raman peaks, arising from strong scattering of phonons by lattice disorder, produced by (and doping-enhanced) spin-states admixture of the Co3+ ions. The thermal conductivity anomalously deviates from ˜1/T behaviour at high (room) temperatures, expected of an insulator. High-temperature specific heat reveals large decrease in the metal-insulator (M-I) transition temperature with Sr-doping.

New Superconductivity Dome in LaFeAsO1-xFx Accompanied by Structural Transition

NASA Astrophysics Data System (ADS)

Yang, Jie; Zhou, Rui; Wei, Lin-Lin; Yang, Huai-Xin; Li, Jian-Qi; Zhao, Zhong-Xian; Zheng, Guo-Qing

2015-10-01

High temperature superconductivity is often found in the vicinity of antiferromagnetism. This is also true in LaFeAsO$_{1-x}$F$_{x}$ ($x \\leq$ 0.2) and many other iron-based superconductors, which leads to proposals that superconductivity is mediated by fluctuations associated with the nearby magnetism. Here we report the discovery of a new superconductivity dome without low-energy magnetic fluctuations in LaFeAsO$_{1-x}$F$_{x}$ with 0.25$\\leq x \\leq$0.75, where the maximal critical temperature $T_c$ at $x_{opt}$ = 0.5$\\sim$0.55 is even higher than that at $x \\leq$ 0.2. By nuclear magnetic resonance and Transmission Electron Microscopy, we show that a C4 rotation symmetry-breaking structural transition takes place for $x>$ 0.5 above $T_c$. Our results point to a new paradigm of high temperature superconductivity.

Magnetic studies of high Tc superconducting (La0.9Sr0.1)2CuO4-y

NASA Technical Reports Server (NTRS)

Zirngiebl, E.; Thompson, J. D.; Huang, C. Y.; Hor, P. H.; Meng, R. L.

1987-01-01

The magnetic moment of La(0.9Sr0.1)2CuO4-y was measured as a function of temperature and magnetic field, and the onset of superconductivity was found to occur at a temperature of 35 K. At 2 K, the dc magnetic susceptibility was found to reach 83 percent of perfect diamagnetism. Field studies have shown that the sample is a type-II superconductor and that the temperature dependences of the critical fiedls are anomalous. Its critical fields, kappa, and lambda(eff) are much larger than those for (La0.9Ba0.1)2CuO4-y, and their temperature dependences cannot be explained in terms of BCS theory.

Gamma-Ray Simulated Spectrum Deconvolution of a LaBr₃ 1-in. x 1-in. Scintillator for Nondestructive ATR Fuel Burnup On-Site Predictions

DOE PAGES

Navarro, Jorge; Ring, Terry A.; Nigg, David W.

2015-03-01

A deconvolution method for a LaBr₃ 1"x1" detector for nondestructive Advanced Test Reactor (ATR) fuel burnup applications was developed. The method consisted of obtaining the detector response function, applying a deconvolution algorithm to 1”x1” LaBr₃ simulated, data along with evaluating the effects that deconvolution have on nondestructively determining ATR fuel burnup. The simulated response function of the detector was obtained using MCNPX as well with experimental data. The Maximum-Likelihood Expectation Maximization (MLEM) deconvolution algorithm was selected to enhance one-isotope source-simulated and fuel- simulated spectra. The final evaluation of the study consisted of measuring the performance of the fuel burnup calibrationmore » curve for the convoluted and deconvoluted cases. The methodology was developed in order to help design a reliable, high resolution, rugged and robust detection system for the ATR fuel canal capable of collecting high performance data for model validation, along with a system that can calculate burnup and using experimental scintillator detector data.« less

Quasi-two-dimensional spin and phonon excitations in La 1.965Ba 0.035CuO 4

DOE PAGES

Wagman, J. J.; Parshall, D.; Stone, Matthew B.; ...

2015-06-03

Here, we present time-of-fight inelastic neutron scattering measurements of La 1.965Ba 0.035CuO 4 (LBCO), a lightly doped member of the high temperature superconducting La-based cuprate family. By using time-of-flight neutron instrumentation coupled with single crystal sample rotation we obtain a four-dimensional data set (three Q and one energy) that is both comprehensive and spans a large region of reciprocal space. Our measurements identify rich structure in the energy dependence of the highly dispersive spin excitations, which are centered at equivalent (1/2, 1/2, L) wave-vectors. These structures correlate strongly with several crossings of the spin excitations with the lightly dispersive phononsmore » found in this system. These eects are signicant and account for on the order of 25% of the total inelastic scattering for energies between ≈5 and 40meV at low |Q|. Interestingly, this scattering also presents little or no L-dependence. As the phonons and dispersive spin excitations centred at equivalent (1/2, 1/2, L) wave-vectors are common to all members of La-based 214 copper oxides, we conclude such strong quasi-two dimensional scattering enhancements are likely to occur in all such 214 families of materials, including those concentrations corresponding to superconducting ground states. Such a phenomenon appears to be a fundamental characteristic of these materials and is potentially related to superconducting pairing.« less

Effect of strontium substitution on the structural and magnetic properties of La1.8Sr0.2MMnO6 (M = Ni, Co)-layered manganites

NASA Astrophysics Data System (ADS)

Karimunnesa, Syeda; Ahmmad, Bashir; Basith, M. A.

2017-07-01

Sr-substituted perovskites, La1.8Sr0.2MMnO6 (M = Ni, Co), were synthesized using the solid-state reaction technique to present a systematic study on their morphological, structural and magnetic properties. The average grain size of the as-prepared La1.8Sr0.2NiMnO6 samples are in the range of 0.2-0.7 µm and those for La1.8Sr0.2CoMnO6 manganites are 0.1-2.8 μm, which is significantly less than that of unsubstituted La2NiMnO6 (LNMO) and La2CoMnO6 (LCMO) manganites. The XPS analysis enlightened about phase purity, binding energy and oxygen vacancy of La1.8Sr0.2MMnO6 manganites. The Sr-substituted LNMO has revealed a sharp ferromagnetic to paramagnetic phase transition at 160 ± 2 K, which is about 120 K less than that of parent LNMO. The Sr-substituted LCMO exhibited such a transition at 220 ± 2 K, which is 8 K less than that of parent LCMO. The temperature-dependent magnetization measurements suggest that the effect of Sr on the transition temperature in LNMO is more significant than that of LCMO.

The La{sub 2}S{sub 3}-LaS{sub 2} system: Thermodynamic and kinetic study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasilyeva, I.G., E-mail: kamarz@niic.nsc.r; Nikolaev, R.E.

2010-08-15

A detailed thermodynamic study of the LaS{sub 2}-La{sub 2}S{sub 3} system in the temperature range 350-1000 {sup o}C was performed, starting from high quality crystals LaS{sub 2} as the highest polysulfide in the system, and using a sensitive static tensimetric method with a quartz Bourdon gauge and a membrane as a null-point instrument. The p{sub S}-T-x diagram obtained has shown that the phase region covering the composition between LaS{sub 2} and La{sub 2}S{sub 3}, which was previously described as a single grossly nonstoichiometric phase, consists of three discrete stoichiometric phases, LaS{sub 2.00}, LaS{sub 1.91}, and LaS{sub 1.76}, where compositions couldmore » be determined with an accuracy of {+-}0.01 f.u. The thermodynamic characteristics of evaporation of the polysulfides as well as standard heat of LaS{sub 2} formation were calculated. The role of kinetics in the formation of ordered superstructures of sulfur-poorer polysulfides with different formal concentration of vacancies is considered. - Graphical abstract: The p{sub S}-T stability fields for La-polysulfides in the concentration range between LaS{sub 2} and La{sub 2}S{sub 3}.« less

Water electrolysis on La 1-xSr xCoO 3-δ perovskite electrocatalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mefford, J. Tyler; Rong, Xi; Abakumov, Artem M.

2016-03-23

Perovskite oxides are attractive candidates as catalysts for the electrolysis of water in alkaline energy storage and conversion systems. However, the rational design of active catalysts has been hampered by the lack of understanding of the mechanism of water electrolysis on perovskite surfaces. Key parameters that have been overlooked include the role of oxygen vacancies, B–O bond covalency, and redox activity of lattice oxygen species. Here we present a series of cobaltite perovskites where the covalency of the Co–O bond and the concentration of oxygen vacancies are controlled through Sr 2+ substitution into La 1-xSr xCoO 3-δ. We attempt tomore » rationalize the high activities of La 1-xSr xCoO 3-δ through the electronic structure and participation of lattice oxygen in the mechanism of water electrolysis as revealed through ab initio modelling. Using this approach, we report a material, SrCoO 2.7, with a high, room temperature-specific activity and mass activity towards alkaline water electrolysis.« less

Water electrolysis on La 1-xSr xCoO 3-δ perovskite electrocatalysts

DOE PAGES

Mefford, J. Tyler; Rong, Xi; Abakumov, Artem M.; ...

2016-03-23

Here, perovskite oxides are attractive candidates as catalysts for the electrolysis of water in alkaline energy storage and conversion systems. However, the rational design of active catalysts has been hampered by the lack of understanding of the mechanism of water electrolysis on perovskite surfaces. Key parameters that have been overlooked include the role of oxygen vacancies, B–O bond covalency, and redox activity of lattice oxygen species. Here we present a series of cobaltite perovskites where the covalency of the Co–O bond and the concentration of oxygen vacancies are controlled through Sr 2+ substitution into La 1–xSr xCoO 3–δ. We attemptmore » to rationalize the high activities of La 1–xSr xCoO 3–δ through the electronic structure and participation of lattice oxygen in the mechanism of water electrolysis as revealed through ab initio modelling. Using this approach, we report a material, SrCoO 2.7, with a high, room temperature-specific activity and mass activity towards alkaline water electrolysis.« less

Influence of electron doping on the ground state of (Sr 1-xLa x) 2IrO 4

DOE PAGES

Chen, Xiang; Hogan, Tom; Walkup, D.; ...

2015-08-17

The evolution of the electronic properties of electron-doped (Sr 1-xLa x) 2IrO 4 is experimentally explored as the doping limit of La is approached. As electrons are introduced, the electronic ground state transitions from a spin-orbit Mott phase into an electronically phase separated state, where long-range magnetic order vanishes beyond x = 0:02 and charge transport remains percolative up to the limit of La substitution (x =0:06). In particular, the electronic ground state remains inhomogeneous even beyond the collapse of the parent state's long-range antiferromagnetic order, while persistent short-range magnetism survives up to the highest La-substitution levels. Furthermore, as electronsmore » are doped into Sr 2IrO 4, we observe the appearance of a low temperature magnetic glass-like state intermediate to the complete suppression of antiferromagnetic order. Universalities and di erences in the electron-doped phase diagrams of single layer and bilayer Ruddlesden-Popper strontium iridates are discussed.« less

Dielectric properties of layered perovskite Sr1-xAxBi2Nb2O9 ferroelectrics (A=La, Ca and x=0,0.1)

NASA Astrophysics Data System (ADS)

Forbess, M. J.; Seraji, S.; Wu, Y.; Nguyen, C. P.; Cao, G. Z.

2000-05-01

In this letter, we report an experimental study on the influences of 10 at. % Ca2+ and La3+ doping on dielectric properties and dc conductivity of SrBi2Nb2O9 ferroelectric ceramics. All the samples were made by two-step solid-state reaction sintering at temperatures up to 1150 °C for 0.5-1 h in air. X-ray diffraction analysis indicated that single-phase layered perovskite ferroelectrics were obtained and no appreciable secondary phase was found. The Curie point was found to increase from 418 °C without doping to 475 °C with Ca2+ doping and to 480 °C with La3+ doping. Dielectric constants, loss tangent, and dc conductivity of SrBi2Nb2O9 ferroelectrics doped with Ca2+ and La3+ were studied and the relationships among doping, crystal structure, and dielectric properties were discussed.

ALA/LA ameliorates glucose toxicity on HK-2 cells by attenuating oxidative stress and apoptosis through the ROS/p38/TGF-β1 pathway.

PubMed

Jiang, Mingxia; Zhang, Haifen; Zhai, Lijie; Ye, Bianliang; Cheng, Yin; Zhai, Chengkai

2017-11-16

Growing evidence indicates that oxidative stress (OS) plays a pivotal role in Diabetic nephropathy (DN). In a previous study we demonstrated that ALA/LA protected HK-2 cells against high glucose-induced cytotoxicity. So we aimed to establish the glucose injury model of HK-2 cells and investigate the beneficial effects of ALA/LA on high glucose-induced excessive production of TGF-β1 and the possible mechanisms mediating the effects. The expression of OS markers in high glucose-induced HK-2 cells treated with ALA/LA., including the antioxidant enzymes and reactive oxygen species (ROS) production, as well as the apoptosis rate were assayed by ELISA and flow cytometry. The p38/transforming growth factor β 1 (TGF-β 1 ) signal pathway were measured by real-time RT-PCR and western blot. The modeling condition of glucose toxicity on HK-2 cells was at the glucose concentration of 40.9 mM. ALA/LA can significantly increase the activities of antioxidant enzymes and decrease ROS production stimulated by high glucose. The study also found that ALA/LA caused a decrease in the apoptosis rate and TGF-β 1 level of HK-2 cells under high glucose stress through the ROS/p38 pathway. ALA/LA exerts protective effects in vitro through inhibition of ROS generation, down regulation of the activation of the p38MAPK pathway and the expression of TGF-β 1 in HK-2 cells.

Effets de la formation sur la violence conjugale

PubMed Central

Zaher, Eman; Keogh, Kelly; Ratnapalan, Savithiri

2014-01-01

Résumé Objectif Décrire et évaluer l’efficacité de la formation concernant la violence conjugale pour améliorer les connaissances et permettre la reconnaissance et la prise en charge par les médecins des femmes victimes de violence. Sources des données On a fait une recension dans la base de données des révisions systématiques de Cochrane, MEDLINE, PubMed, PsycINFO, ERIC et EMBASE pour trouver des articles publiés entre le 1e janvier 2000 et le 1e novembre 2012. Des recherches manuelles ont complété cette recension pour cerner des articles pertinents à l’aide d’une stratégie de recherche combinant des textes, mots et expressions MeSH. Sélection des études On a choisi des études randomisées contrôlées qui portaient sur des interventions éducatives à l’intention des médecins et fournissaient des données sur les effets des interventions. Synthèse On a inclus 9 études randomisées contrôlées qui décrivaient différentes approches pédagogiques et diverses mesures des résultats. Trois études examinaient les effets d’interventions éducatives pour des médecins en formation postdoctorale et ont constaté une augmentation des connaissances, mais il n’y a eu aucun changement dans le comportement en ce qui a trait à l’identification des victimes de violence conjugale. Six études portaient sur des interventions éducatives pour des médecins en pratique active. Trois d’entre elles utilisaient une approche à multiples facettes pour les médecins, qui combinait une formation ainsi que des interventions de soutien de la part du système pour changer les comportements des médecins, comme une sensibilisation générale accrue à la violence conjugale au moyen de brochures et d’affiches, des aide-mémoire pour rappeler aux médecins comment identifier les victimes, des moyens pour faciliter l’accès des médecins à des services de soutien pour les victimes, la réalisation d’audits et la fourniture de rétroaction. Les

Fotometria WHBY |o lll|/HB de Regiones H 11 Y la HISTORIA de la Formacion ESTELAR Reciente EN la PEQUENA NUBE de Magallanes

NASA Astrophysics Data System (ADS)

Copetti, M. V. F.; Dottori, H. A.

1987-05-01

El ancho equivalente WHβ de la linea de Hβ en emisión y la razón [0 III]/Hβ del par λλ4959, 50 7 A del [0111], fueron medidos en 23 regiones HII de la Peque˜a Nube de Magallanes, por medio de la fotometría fotoeléctrica a través de un sistema de tres filtros interferenciales: dos Hβ , con bandas pasantes de 100 y 30 A, y un [0111] centrado en 5000 A y con banda pasante de 50 A. Las observaciones fueron realizadas con los telescopios de 1.60-m y 0.60-m del Laboratorio Nacional de Astrofísica, Brasópolis, Brasil. Fueron escogidos diafragmas suficientemente grandes para captar la radiación integrada de cada región HII. Las medidas fueron calibradas por comparación a un conjunto de nebulosas planetarias con flujos absolutos bien definidos. A través de la comparación entre los datos observacionales y modelos evolutivos de WHβ y [0 III] /Hβ (Copetti et al.1986', Astr. and Ap., 156, 111), las edades de las regiones HIl fueron estimadas. Basada en la distribución espacial de las edades de regiones HIl, la historia de la formación estelar reciente en la Pequeña Nube de Magallanes es analizada. La similitud de las medidas de WH&beta y [OIII]/WHβ entre las regiones H II observadas sugiere que hubo una explosión de formación estelar a 4±1 x106 años en la Pequeña Nube de Magallanes. (Parcialmente financiado por CNPq).

Electronic structure and chemical bonding in La1-x Sr x MnO3 perovskite ceramics

NASA Astrophysics Data System (ADS)

Thenmozhi, N.; Sasikumar, S.; Sonai, S.; Saravanan, R.

2017-04-01

This study reports on the synthesis of La1-x Sr x MnO3 (x  =  0.3, 0.4 and 0.5) manganites by high temperature solid state reaction method using lanthanum oxide, strontium carbonate and manganese oxide as starting materials. The synthesized samples were characterized by XRD, UV-vis, SEM/EDS and VSM. Structural characterization shows that all the prepared samples have the perovskite rhombohedral structure. Influence of Sr doping on electron density distributions in the lattice structure of LaMnO3 were analyzed through maximum entropy method (MEM). Cell parameters are found to be decreasing with the addition of Sr content. The qualitative and quantitative analysis by MEM reveals that, incorporation of Sr into LaMnO3 lattice enhances the ionic nature between La and O ions and decreases the covalent nature between Mn and O ions. Optical band gap values are determined from the UV-visible absorption spectra. Particles with polygonal form are observed from the SEM micrographs. The elemental compositions of the synthesized samples are confirmed by EDS. The magnetic properties studied from the M-H plot taken at room temperature indicated that, the prepared samples are exhibited ferromagnetic behavior.

Crystal growth and characterization of the CMR compound La 1.2(Sr,Ca) 1.8Mn 2O 7

NASA Astrophysics Data System (ADS)

Velázquez, M.; Haut, C.; Hennion, B.; Revcolevschi, A.

2000-12-01

High-quality centimeter-sized single crystals of La 1.2Sr 1.8- yCa yMn 2O 7 (0.0⩽ y⩽0.2) were successfully grown using a floating zone method associated with an image furnace. We present the growth conditions together with a characterization of the single crystals by means of optical and electron microscopy, EDX and ICP⧸AES analysis, DTA-TGA measurements and redox titration, X-ray powder diffraction, Laue X-ray back-reflection and neutron diffraction. We also stress the main aspects of the complex thermodynamical and kinetic behaviors of these compounds.

[Epidemiological study of type 1 diabetes in children under 15 years-old in Castilla-La Mancha (Spain)].

PubMed

Muiña, P Giralt; Herrera, M J Ballester; Atance, E Palomo; Donado, J J Angulo; Sánchez, G; Ferrer, L Santillana

2012-02-01

We studied the incidence and prevalence of type 1 diabetes in children under 15 years-old in Castilla-La Mancha. Incidence: All new cases in a 12 months period (2007-2008) were included. To calculate the completeness of ascertainment we used the capture-recapture method. The result is expressed in cases/100,000 inhabitants under 15 years old/year. Prevalence: all children under 15 years diagnosed with diabetes on 31(st) of May of 2008 were registered. Results are expressed as cases/1000 inhabitants under 15 years old. The incidence in the Castilla-La Mancha was 27.6/100,000/year, but there was a wide variability among the different provinces: Ciudad Real (34.15), Albacete (28.19), Toledo (26.57), Guadalajara (20.3) and Cuenca (17.6). The prevalence was 1.44/1000 children under 15 years old and 0.21/1000 for the whole population. By provinces: Ciudad Real (1.67), Albacete (1.64), Toledo (1.42), Cuenca (1.02) and Guadalajara (1.01). By sex and age, we found a higher incidence (13/7) and prevalence (22/7) in males under 5 years old. The age group with highest incidence was the 4-9 year-olds, and the highest prevalence was in the 10-14 years group. Both, incidence and prevalence of type 1 diabetes in children under 15 years old in Castilla-La Mancha are high, with a wide range among the different provinces. There is a preponderance in males under 5 years old. The highest prevalence is that of the 10-14 years age group. The highest incidence was in the 5-10 year age group. Copyright © 2010 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.

Effect of microstructure on the thermoelectric performance of La{sub 1−x}Sr{sub x}CoO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viskadourakis, Z.; Department of Mechanical and Manufacturing Engineering, University of Cypruss, 75 Kallipoleos Avenue, P.O. Box 20537, 1678 Nicosia; Athanasopoulos, G.I.

We present a case where the microstructure has a profound effect on the thermoelectric properties of oxide compounds. Specifically, we have investigated the effect of different sintering treatments on La{sub 1−x}Sr{sub x}CoO{sub 3} samples synthesized using the Pechini method. We found that the samples, which are dense and consist of inhomogeneously-mixed grains of different size, exhibit both higher Seebeck coefficient and thermoelectric figure of merit than the samples, which are porous and consist of grains with almost identical size. The enhancement of Seebeck coefficient in the dense samples is attributed to the so-called “energy-filtering” mechanism that is related to themore » energy barrier of the grain boundary. On the other hand, the thermal conductivity for the porous compounds is significantly reduced in comparison to the dense compounds. It is suggested that a fine-manipulation of grain size ratio combined with a fine-tuning of porosity could considerably enhance the thermoelectric performance of oxides. - Graphical abstract: The enhancement of the dimensionless thermoelectric figure ZT of merit is presented for two equally Sr-doped LaCoO3 compounds, possessing different microstructure, indicating the effect of the latter to the thermoelectric performance of the La{sub 1−x}Sr{sub x}CoO{sub 3} solid solution. - Highlights: • Electrical and thermal transport properties are affected by the microstructure in La{sub 1−x}Sr{sub x}CoO{sub 3} polycrystalline materials. • Coarse/fine grain size distribution enhances the Seebeck coefficient. • Porosity reduces the thermal conductivity in La{sub 1−x}Sr{sub x}CoO{sub 3} polycrystalline samples. • The combination of large/small grain ratio distribution with the high porosity may result to the enhancement of the thermoelectric performance of the material.« less

Superconductivity and Magnetism in LaO1-xFxFeAs

NASA Astrophysics Data System (ADS)

Buechner, Bernd

2009-03-01

Measuring ^75As, ^139La, and ^57Fe Nuclear Magnetic Resonance (NMR) as well as μSR, transport and thermodynamic properties we have determined the phase diagram of LaO1-xFxAsFe superconductors [1-6]. In my talk, I will show experimental studies of the magnetic ordering [2, 5], properties of the superconducting state [1, 3, 5] and the normal state properties [1, 4, 6] in the superconducting regions of the phase diagram. While the temperature dependence of the London penetration as determined from μSR points to an isotropic s wave state [3], our early NMR data suggest singlet pairing and nodes of the order parameter [1]. Extending the NMR work to lower temperatures we find evidence for a deviation of the T^3 behaviour of the spin lattice relaxation, which would agree with the extended s-wave symmetry suggested in recent theoretical work. In the paramagnetic normal state, NMR on all three nuclei shows that the local electronic susceptibility rises with increasing temperature. This had led to suggest the presence of a pseudogap, which I will discuss in detail. The scaling of all NMR shifts with respect to the macroscopic susceptibility indicates that there is no apparent multiband effect through preferential hyperfine couplings. Relaxation measurements indicate a similar temperature-dependence for (T1T)-1, and suggest that the dynamical susceptibility changes uniformly in q space with varying temperature. The transport properties show some striking similarities to the findings in cuprates [6] and, finally, susceptibility [4] as well as NMR studies point to the antiferromagnetic fluctuations, whose relevance is also discussed in many theoretical models of the superconducting pairing mechanism. In collaboration with Hans-Joachim Grafe, Christian Hess, R"udiger Klingeler, G"unter Behr, Agnieszka Kondrat, Norman Leps, and Guillaume Lang, IFW Dresden; Hans-Henning Klauss, TU Dresden; and Hubertus Luetkens, PSI Villigen. [4pt] References: [0pt] [1] H.-J. Grafe et al., Phys

Effets de la pollution de l’air sur la santé

PubMed Central

Abelsohn, Alan; Stieb, Dave M.

2011-01-01

Résumé Objectif Faire connaître aux médecins de famille les effets de la pollution atmosphérique sur la santé et indiquer quels conseils donner aux patients vulnérables pour qu’ils soient moins exposés. Sources de l’information On a consulté MEDLINE à l’aide des termes relatifs à la pollution atmosphérique et à ses effets indésirables. On a révisé les articles en anglais publiés entre janvier 2008 et décembre 2009. La plupart des études contenaient des preuves de niveau II. Principal message Au Canada, la pollution de l’air extérieur cause une morbidité et une mortalité importantes. Elle peut affecter le système respiratoire (exacerbation de l’asthme et de la maladie pulmonaire obstructive chronique) et le système cardiovasculaire (déclencher l’arythmie, l’insuffisance cardiaque et les AVC). La cote air santé (CAS) est un nouvel outil de communication mis au point par Santé Canada et Environnement Canada qui indique sur une échelle de 1 à 10, le risque pour la santé causé par la pollution atmosphérique. La CAS est largement diffusée dans les médias et cet outil pourrait être utile au médecin de famille pour inciter les patients à haut risque (comme ceux qui souffrent d’asthme, de maladie pulmonaire obstructive chronique ou d’insuffisance cardiaque) à réduire leur exposition à la pollution atmosphérique. Conclusion Le médecin de famille peut se servir de la CAS et de ses messages sur la santé pour enseigner aux asthmatiques et aux autres patients à risque élevé la façon de réduire les risques pour la santé causés par la pollution atmosphérique.

Electronic conduction in La-based perovskite-type oxides

PubMed Central

Ohbayashi, Kazushige; Koumoto, Kunihito

2015-01-01

A systematic study of La-based perovskite-type oxides from the viewpoint of their electronic conduction properties was performed. LaCo0.5Ni0.5O3±δ was found to be a promising candidate as a replacement for standard metals used in oxide electrodes and wiring that are operated at temperatures up to 1173 K in air because of its high electrical conductivity and stability at high temperatures. LaCo0.5Ni0.5O3±δ exhibits a high conductivity of 1.9 × 103 S cm−1 at room temperature (R.T.) because of a high carrier concentration n of 2.2 × 1022 cm−3 and a small effective mass m∗ of 0.10 me. Notably, LaCo0.5Ni0.5O3±δ exhibits this high electrical conductivity from R.T. to 1173 K, and little change in the oxygen content occurs under these conditions. LaCo0.5Ni0.5O3±δ is the most suitable for the fabrication of oxide electrodes and wiring, though La1−xSrxCoO3±δ and La1−xSrxMnO3±δ also exhibit high electronic conductivity at R.T., with maximum electrical conductivities of 4.4 × 103 S cm−1 for La0.5Sr0.5CoO3±δ and 1.5 × 103 S cm−1 for La0.6Sr0.4MnO3±δ because oxygen release occurs in La1−xSrxCoO3±δ as elevating temperature and the electrical conductivity of La0.6Sr0.4MnO3±δ slightly decreases at temperatures above 400 K. PMID:27877778

Nanostructured Perovskite LaCo1-xMnxO3 as Bifunctional Catalysts for Rechargeable Metal-Air Batteries

NASA Astrophysics Data System (ADS)

Ge, Xiaoming; Li, Bing; Wuu, Delvin; Sumboja, Afriyanti; An, Tao; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

2015-09-01

Bifunctional catalyst that is active for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is one of the most important components of rechargeable metal-air batteries. Nanostructured perovskite bifunctional catalysts comprising La, Co and Mn(LaCo1-xMnxO3, LCMO) are synthesized by hydrothermal methods. The morphology, structure and electrochemical activity of the perovskite bifunctional catalysts are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and rotating disk electrode (RDE) techniques. Nanorod, nanodisc and nanoparticle are typical morphologies of LCMO. The electrocatalytic activity of LCMO is significantly improved by the addition of conductive materials such as carbon nanotube. To demonstrate the practical utilization, LCMO in the composition of LaCo0.8Mn0.2O3(LCMO82) is used as air cathode catalysts for rechargeable zinc-air batteries. The battery prototype can sustain 470 h or 40 discharge-charge cycles equivalent.

Effect of EBI3 on radiation-induced immunosuppression of cervical cancer HeLa cells by regulating Treg cells through PD-1/PD-L1 pathway.

PubMed

Zhang, Song-An; Niyazi, Hu-Er-Xi-Dan; Hong, Wen; Tuluwengjiang, Gu-Li-Xian; Zhang, Lei; Zhang, Yang; Su, Wei-Peng; Bao, Yong-Xing

2017-03-01

This study aimed to investigate the effect of EBI3 on radiation-induced immunosuppression of cervical cancer HeLa cells by regulating Treg cells through PD-1/PD-L1 signaling pathway. A total of 43 adult female Wistar rats were selected and injected with HeLa cells in the caudal vein to construct a rat model of cervical cancer. All model rats were randomly divided into the radiotherapy group ( n = 31) and the control group ( n = 12). The immunophenotype of Treg cells was detected by the flow cytometry. The protein expressions of EBI3, PD-1, and PD-L1 in cervical cancer tissues were tested by the streptavidin-peroxidase method. HeLa cells in the logarithmic growth phase were divided into four groups: the blank, the negative control group, the EBI3 mimics group, and the EBI3 inhibitors group. Western blotting was used to detect PD-1 and PD-L1 protein expressions. MTT assay was performed to measure the proliferation of Treg cells. Flow cytometry was used to detect cell cycle and apoptosis, and CD4 + /CD8 + T cell ratio in each group. Compared with before and 1 week after radiotherapy, the percentages of CD4 + T cells and CD8 + T cells were significantly decreased in the radiotherapy group at 1 month after radiotherapy. Furthermore, down-regulation of EBI3 and up-regulation of PD-1 and PD-L1 were observed in cervical cancer tissues at 1 month after radiotherapy. In comparison to the blank and negative control groups, increased expression of EBI3 and decreased expressions of PD-1 and PD-L1 were found in the EBI3 mimics group. However, the EBI3 inhibitors group had a lower expression of EBI3 and higher expressions of PD-1 and PD-L1 than those in the blank and negative control groups. The EBI3 mimics group showed an increase in the optical density value (0.43 ± 0.05), while a decrease in the optical density value (0.31 ± 0.02) was found in the EBI3 inhibitors group. Moreover, compared with the blank and negative control groups, the apoptosis rates

Inhibitory activity of synthesized acetylated Procyanidin B1 analogs against HeLa S3 cells proliferation.

PubMed

Okamoto, Syuhei; Ishihara, Sayaka; Okamoto, Taisuke; Doi, Syoma; Harui, Kota; Higashino, Yusuke; Kawasaki, Takashi; Nakajima, Noriyuki; Saito, Akiko

2014-02-04

Proanthocyanidins, also known as condensed tannins and/or oligomeric flavonoids, occur in many edible plants and have various interesting biological activities. Previously, we reported a synthetic method for the preparation of various procyanidins in pure form and described their biological activities. Here, we describe the synthesis of procyanidin B1 acetylated analogs and discuss their inhibition activities against HeLa S3 cell proliferation. Surprisingly, the lower-unit acetylated procyanidin B1 strongly inhibited the proliferation of HeLa S3 cells. This molecule showed much stronger inhibitory activity than did epigallocatechin-3-O-gallate (EGCG), green tea polyphenol, and dimeric compounds that included EGCG as a unit. This result suggests that the phenolic hydroxyl groups of the upper-units in flavan-3-ols are important for their inhibitory activity against cancer cell proliferation and that a hydrophobic lower unit dimer enhances this activity.

Intrinsic Josephson junction behaviour of the low Tc superconductor (LaSe) 1.14(NbSe 2)

NASA Astrophysics Data System (ADS)

Kačmarčík, J.; Szabó, P.; Samuely, P.; Rodrigo, J. G.; Suderow, H.; Vieira, S.; Lafond, A.; Meerschaut, A.

2008-04-01

Interlayer magnetotransport measurements on the highly anisotropic (LaSe)1.14(NbSe2) superconductor with Tc ∼ 1.2 K have indicated that this layered compound represents a model system of intrinsic Josephson junctions [P. Szabó et al., Phys. Rev. Lett. 86 (2001) 5990]. Scanning tunneling microscopy at room temperature and tunneling spectroscopy measurements at very low temperatures are presented in this work. STM imaging has revealed the presence of two types of surfaces which can be attributed to the appearance of LaSe or NbSe2 layers on the surface. The use of STM tip made of superconducting lead enabled a precise measurement of the temperature dependence of the superconducting energy gap Δ(T) on the NbSe2 layer. Δ(T) obtained from the surface sensitive STS data support the scenario obtained from our previous interlayer - ergo bulk sensitive magnetotransport measurements.

Probiotic properties of native Lactobacillus spp. strains for dairy calves.

PubMed

Fernández, S; Fraga, M; Silveyra, E; Trombert, A N; Rabaza, A; Pla, M; Zunino, P

2018-04-10

The use of native microorganisms with probiotic capacity is an alternative tool for the treatment and prevention of several diseases that affect animals, such as neonatal calf diarrhoea. The selection of probiotic strains within a collection is based on different in vitro and in vivo assays, which predict their potential. The aim of this study was to characterise a group of native Lactobacillus spp. strains isolated from faeces of healthy calves using an in vitro approach and to assess their ability to colonise the gastrointestinal tract (GIT) of calves. Native Lactobacillus spp. strains were evaluated on their capacity to survive low pH conditions and bile salts presence, biofilm formation and adhesion to both mucus and Caco-2 cells. Based on the in vitro characterisation, four strains (Lactobacillus johnsonii TP1.1, Lactobacillus reuteri TP1.3B, L. johnsonii TP1.6 and Lactobacillus amylovorus TP8.7) were selected to evaluate their capacity to colonise and persist in the GIT of calves. The assessment of enteric persistence involved an in vivo assay with oral administration of probiotics and quantification in faeces of the administered bacterial species with real-time quantitative PCR (qPCR). The study was conducted using 15 calves (1-month-old) which were divided into five groups of three animals, four of which were treated with four different selected strains and one was the control group. Strains TP1.3B and TP1.6 managed to persist in treated animals until ten days after the end of the administration period, indicating that they could be promising candidates for the design of probiotics for calves.

Faecal D/L Lactate Ratio Is a Metabolic Signature of Microbiota Imbalance in Patients with Short Bowel Syndrome

PubMed Central

Mayeur, Camille; Gratadoux, Jean-Jacques; Bridonneau, Chantal; Chegdani, Fatima; Larroque, Béatrice; Kapel, Nathalie; Corcos, Olivier; Thomas, Muriel; Joly, Francisca

2013-01-01

Our objective was to understand the functional link between the composition of faecal microbiota and the clinical characteristics of adults with short bowel syndrome (SBS). Sixteen patients suffering from type II SBS were included in the study. They displayed a total oral intake of 2661±1005 Kcal/day with superior sugar absorption (83±12%) than protein (42±13%) or fat (39±26%). These patients displayed a marked dysbiosis in faecal microbiota, with a predominance of Lactobacillus/Leuconostoc group, while Clostridium and Bacteroides were under-represented. Each patient exhibited a diverse lactic acid bacteria composition (L. delbrueckii subsp. bulgaricus, L. crispatus, L. gasseri, L. johnsonii, L. reuteri, L. mucosae), displaying specific D and L-lactate production profiles in vitro. Of 16 patients, 9/16 (56%) accumulated lactates in their faecal samples, from 2 to 110 mM of D-lactate and from 2 to 80 mM of L-lactate. The presence of lactates in faeces (56% patients) was used to define the Lactate-accumulator group (LA), while absence of faecal lactates (44% patients) defines the Non lactate-accumulator group (NLA). The LA group had a lower plasma HCO3− concentration (17.1±2.8 mM) than the NLA group (22.8±4.6 mM), indicating that LA and NLA groups are clinically relevant sub–types. Two patients, belonging to the LA group and who particularly accumulated faecal D-lactate, were at risk of D-encephalopathic reactions. Furthermore, all patients of the NLA group and those accumulating preferentially L isoform in the LA group had never developed D-acidosis. The D/L faecal lactate ratio seems to be the most relevant index for a higher D- encephalopathy risk, rather than D- and L-lactate faecal concentrations per se. Testing criteria that take into account HCO3− value, total faecal lactate and the faecal D/L lactate ratio may become useful tools for identifying SBS patients at risk for D-encephalopathy. PMID:23372709

A Chinese rhesus macaque (Macaca mulatta) model for vaginal Lactobacillus colonization and live microbicide development

PubMed Central

Yu, Rosa R.; Cheng, Andrew T.; Lagenaur, Laurel A.; Huang, Wenjun; Weiss, Deborah E.; Treece, Jim; Sanders-Beer, Brigitte E.; Hamer, Dean H.; Lee, Peter P.; Xu, Qiang; Liu, Yang

2015-01-01

Background We sought to establish a nonhuman primate model of vaginal Lactobacillus colonization suitable for evaluating live microbial microbicide candidates. Methods Vaginal and rectal microflora in Chinese rhesus macaques (Macaca mulatta) were analyzed, with cultivable bacteria identified by 16S rRNA gene sequencing. Live lactobacilli were intravaginally administered to evaluate bacterial colonization. Results Chinese rhesus macaques harbored abundant vaginal Lactobacillus, with Lactobacillus johnsonii as the predominant species. Like humans, most examined macaques harbored only one vaginal Lactobacillus species. Vaginal and rectal Lactobacillus isolates from the same animal exhibited different genetic and biochemical profiles. Vaginal Lactobacillus was cleared by a vaginal suppository of azithromycin, and endogenous L. johnsonii was subsequently restored by intravaginal inoculation. Importantly, prolonged colonization of a human vaginal Lactobacillus jensenii was established in these animals. Conclusions The Chinese rhesus macaque harbors vaginal Lactobacillus and is a potentially useful model to support the pre-clinical evaluation of Lactobacillus-based topical microbicides. PMID:19367737

Prospects for Engineering Thermoelectric Properties in La1/3NbO3 Ceramics Revealed via Atomic-Level Characterization and Modeling.

PubMed

Kepaptsoglou, Demie; Baran, Jakub D; Azough, Feridoon; Ekren, Dursun; Srivastava, Deepanshu; Molinari, Marco; Parker, Stephen C; Ramasse, Quentin M; Freer, Robert

2018-01-02

A combination of experimental and computational techniques has been employed to explore the crystal structure and thermoelectric properties of A-site-deficient perovskite La 1/3 NbO 3 ceramics. Crystallographic data from X-ray and electron diffraction confirmed that the room temperature structure is orthorhombic with Cmmm as a space group. Atomically resolved imaging and analysis showed that there are two distinct A sites: one is occupied with La and vacancies, and the second site is fully unoccupied. The diffuse superstructure reflections observed through diffraction techniques are shown to originate from La vacancy ordering. La 1/3 NbO 3 ceramics sintered in air showed promising high-temperature thermoelectric properties with a high Seebeck coefficient of S 1 = -650 to -700 μV/K and a low and temperature-stable thermal conductivity of k = 2-2.2 W/m·K in the temperature range of 300-1000 K. First-principles electronic structure calculations are used to link the temperature dependence of the Seebeck coefficient measured experimentally to the evolution of the density of states with temperature and indicate possible avenues for further optimization through electron doping and control of the A-site occupancies. Moreover, lattice thermal conductivity calculations give insights into the dependence of the thermal conductivity on specific crystallographic directions of the material, which could be exploited via nanostructuring to create high-efficiency compound thermoelectrics.

Changes in the electronic structure and spin dynamics across the metal-insulator transition in LaLa 1-xSr xCoO 3

DOE PAGES

Smith, R. X.; Hoch, M. J. R.; Moulton, W. G.; ...

2016-01-25

The magnetoelectronic properties of La 1-xSr xCoO 3, which include giant magnetoresistance, are strongly dependent on the level of hole doping. The system evolves, with increasing x, from a spin glass insulator to a metallic ferromagnet with a metal-insulator (MI) transition at x C ~ 0.18. Nanoscale phase separation occurs in the insulating phase and persists, to some extent, into the just-metallic phase. The present experiments at 4.2 K have used 139La NMR to investigate the transition from hopping dynamics for x < x C to Korringa-like ferromagnetic metal behavior for x > x C. A marked decrease in themore » spin-lattice relaxation rate is found in the vicinity of x C as the MI transition is crossed. Lastly, this behavior is accounted for in terms of the evolution of the electronic structure and dynamics with cluster size.« less

Site-selective doping and superconductivity in (La1-yPry)(Ba2-xLax)Cu3O7+δ

NASA Astrophysics Data System (ADS)

Mitzi, D. B.; Feffer, P. T.; Newsam, J. M.; Webb, D. J.; Klavins, P.; Jacobson, A. J.; Kapitulnik, A.

1988-10-01

Samples in the quaternary system (La1-yPry)(Ba2-xLax)Cu3O7+δ have been prepared and characterized using x-ray and neutron diffraction, thermogravimetric analysis, and transport and magnetic measurements. Pr substitutes on the oxygen-depleted La layers for y>0.0, while La substitutes on the Ba sites for x>0.0. The effect of doping on each site is inferred to be primarily local, affecting immediately adjacent Cu-O layers. The similar suppression of superconductivity that accompanies doping on each of the two distinct sites apparently correlates with the degree of oxidation of the Cu-O sheets (and not the chains), indicating that the sheets support the high temperature superconductivity. Comparison of orthorhombic and tetragonal samples with similar Ba:La ratios (and y=0) demonstrates that the orthorhombic phase yields the largest Meissner signals and highest transition temperatures in the La(Ba2-xLax)Cu3O7+δ system. The effect on superconductivity of oxygen-vacancy configuration in the Cu-O chain layers is proposed to derive, indirectly, from their influence on the Cu-O sheets. In addition, optimally superconducting La(Ba2-xLax)Cu3O7+δ samples exhibit interesting normal-state magnetic properties, with a paramagnetic susceptibility that decreases steadily with temperature between 350 K and Tc.

La-related Protein 1 (LARP1) Represses Terminal Oligopyrimidine (TOP) mRNA Translation Downstream of mTOR Complex 1 (mTORC1).

PubMed

Fonseca, Bruno D; Zakaria, Chadi; Jia, Jian-Jun; Graber, Tyson E; Svitkin, Yuri; Tahmasebi, Soroush; Healy, Danielle; Hoang, Huy-Dung; Jensen, Jacob M; Diao, Ilo T; Lussier, Alexandre; Dajadian, Christopher; Padmanabhan, Niranjan; Wang, Walter; Matta-Camacho, Edna; Hearnden, Jaclyn; Smith, Ewan M; Tsukumo, Yoshinori; Yanagiya, Akiko; Morita, Masahiro; Petroulakis, Emmanuel; González, Jose L; Hernández, Greco; Alain, Tommy; Damgaard, Christian K

2015-06-26

The mammalian target of rapamycin complex 1 (mTORC1) is a critical regulator of protein synthesis. The best studied targets of mTORC1 in translation are the eukaryotic initiation factor-binding protein 1 (4E-BP1) and ribosomal protein S6 kinase 1 (S6K1). In this study, we identify the La-related protein 1 (LARP1) as a key novel target of mTORC1 with a fundamental role in terminal oligopyrimidine (TOP) mRNA translation. Recent genome-wide studies indicate that TOP and TOP-like mRNAs compose a large portion of the mTORC1 translatome, but the mechanism by which mTORC1 controls TOP mRNA translation is incompletely understood. Here, we report that LARP1 functions as a key repressor of TOP mRNA translation downstream of mTORC1. Our data show the following: (i) LARP1 associates with mTORC1 via RAPTOR; (ii) LARP1 interacts with TOP mRNAs in an mTORC1-dependent manner; (iii) LARP1 binds the 5'TOP motif to repress TOP mRNA translation; and (iv) LARP1 competes with the eukaryotic initiation factor (eIF) 4G for TOP mRNA binding. Importantly, from a drug resistance standpoint, our data also show that reducing LARP1 protein levels by RNA interference attenuates the inhibitory effect of rapamycin, Torin1, and amino acid deprivation on TOP mRNA translation. Collectively, our findings demonstrate that LARP1 functions as an important repressor of TOP mRNA translation downstream of mTORC1. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

La-related Protein 1 (LARP1) Represses Terminal Oligopyrimidine (TOP) mRNA Translation Downstream of mTOR Complex 1 (mTORC1)*

PubMed Central

Fonseca, Bruno D.; Zakaria, Chadi; Jia, Jian-Jun; Graber, Tyson E.; Svitkin, Yuri; Tahmasebi, Soroush; Healy, Danielle; Hoang, Huy-Dung; Jensen, Jacob M.; Diao, Ilo T.; Lussier, Alexandre; Dajadian, Christopher; Padmanabhan, Niranjan; Wang, Walter; Matta-Camacho, Edna; Hearnden, Jaclyn; Smith, Ewan M.; Tsukumo, Yoshinori; Yanagiya, Akiko; Morita, Masahiro; Petroulakis, Emmanuel; González, Jose L.; Hernández, Greco; Alain, Tommy; Damgaard, Christian K.

2015-01-01

The mammalian target of rapamycin complex 1 (mTORC1) is a critical regulator of protein synthesis. The best studied targets of mTORC1 in translation are the eukaryotic initiation factor-binding protein 1 (4E-BP1) and ribosomal protein S6 kinase 1 (S6K1). In this study, we identify the La-related protein 1 (LARP1) as a key novel target of mTORC1 with a fundamental role in terminal oligopyrimidine (TOP) mRNA translation. Recent genome-wide studies indicate that TOP and TOP-like mRNAs compose a large portion of the mTORC1 translatome, but the mechanism by which mTORC1 controls TOP mRNA translation is incompletely understood. Here, we report that LARP1 functions as a key repressor of TOP mRNA translation downstream of mTORC1. Our data show the following: (i) LARP1 associates with mTORC1 via RAPTOR; (ii) LARP1 interacts with TOP mRNAs in an mTORC1-dependent manner; (iii) LARP1 binds the 5′TOP motif to repress TOP mRNA translation; and (iv) LARP1 competes with the eukaryotic initiation factor (eIF) 4G for TOP mRNA binding. Importantly, from a drug resistance standpoint, our data also show that reducing LARP1 protein levels by RNA interference attenuates the inhibitory effect of rapamycin, Torin1, and amino acid deprivation on TOP mRNA translation. Collectively, our findings demonstrate that LARP1 functions as an important repressor of TOP mRNA translation downstream of mTORC1. PMID:25940091

Cambios históricos en el aporte terrígeno de la cuenca del Río de la Plata sobre la plataforma interna Uruguaya

NASA Astrophysics Data System (ADS)

Marrero, Analía; Tudurí, Adriana; Pérez, Laura; Cuña, Caroline; Muniz, Pablo; Lopes Figueira, Rubens; Michaelovitch de Mahiques, Michel; Alves de Lima Ferreira, Paulo; Pittauerová, Daniela; Hanebuth, Till; García Rodríguez, Felipe

2014-12-01

El Río de la Plata (RdlP) presenta significativas variaciones naturales (hidrodinámicas y oceanográficas) asociadas a diferentes condiciones climáticas. El propósito de este trabajo es inferir los cambios de aportes continentales de sedimentos y su relación con las variaciones hidrológicas del Río de la Plata, a través del análisis de proxies sedimentológicos y geoquímicos en testigos de sedimentos de la plataforma interna uruguaya que registran los últimos 100 años, aproximadamente. A partir de la datación por 210Pb de dos testigos de sedimentos (GeoB 13813-4 y BAR1) se reconstruyó la geocronología del ambiente, y se relacionó con datos de las forzantes climáticas Pacific Decadal Oscillation, El Niño/La Niña Southern Oscillation, Atlantic Multidecadal Oscillation, y las anomalías hidrológicas de los ríos Paraná y Uruguay. Los valores más positivos y estables del Southern Oscillation Index, los cuales corresponden a fases La Niña, se observan en el periodo correspondiente entre 1910-1970, respecto al resto de la serie, donde se aprecia una mayor variabilidad y una tendencia hacia valores más negativos (eventos El Niño). Se hicieron dendrogramas (clustering) jerárquicos para ambos testigos. Para el testigo GeoB 13813-4, se utilizó la relación Ca/Ti y la granulometría, mientras que para BAR1 se recurrió a variables granulométricas y la tasa de sedimentación. El mayor aporte continental hacia la región de la plataforma adyacente al Río de la Plata registrado a partir del año 1970, podría ser el factor principal de los agrupamientos observados en los clusters para ambos testigos. Las agrupaciones mostraron una diferenciación en la década de 1970, lo que estaría asociado al aumento de los caudales de los ríos Paraná y Uruguay, durante las últimas tres décadas del siglo XX. Por otra parte se observa que la granulometría del testigo BAR1 presentó un mayor tamaño de grano y más variabilidad que en el caso del testigo Geo

Effect of cobalt doping on the structural, magnetic and abnormal thermal expansion properties of NaZn13-type La(Fe1-xCox)11.4Al1.6 compounds.

PubMed

Zhao, Yuqiang; Huang, Rongjin; Li, Shaopeng; Wang, Wei; Jiang, Xingxing; Lin, Zheshuai; Li, Jiangtao; Li, Laifeng

2016-07-27

Cubic NaZn13-type La(Fe1-xCox)11.4Al1.6 compounds were synthesized and extensively explored through crystal structure and magnetization analyses. By optimizing the chemical composition, the isotropic abnormal properties of excellent zero and giant negative thermal expansion in a pure form were both found at different temperature ranges through room temperature. Moreover, the temperature regions with the remarkable abnormal thermal expansion (ATE) properties have been broadened which are controlled by the dM/dT. The present study demonstrates that the ATE behavior mainly depends on special structural and magnetic properties. These diverse properties suggest the high potential of La(Fe1-xCox)11.4Al1.6 for the development of abnormal expansion materials.

Etude de facteurs de risque de la transmission du VIH de la mère à l'enfant dans la stratégie « option A » à Lubumbashi, République Démocratique du Congo

PubMed Central

Ngwej, Dieudonné Tshikwej; Mukuku, Olivier; Mudekereza, Rachel; Karaj, Eugénie; Odimba, Etienne Bwana Fwamba; Luboya, Oscar Numbi; Kakoma, Jean-Baptiste Sakatolo; Wembonyama, Stanis Okitotshio

2015-01-01

Introduction L'infection à VIH chez la femme enceinte a pour principal risque la contamination du nouveau-né. L'objectif est de déterminer le taux de transmission du VIH de la mère à l'enfant (TME) dans la ville de Lubumbashi et en évaluer les facteurs de risque. Méthodes Il s'agissait d'une étude prospective transversale à visée analytique de 157 accouchées séropositives au VIH et de leurs enfants dans 12 structures sanitaires de Lubumbashi (RDCongo) du 1er octobre 2012 au 31 décembre 2013. Les paramètres sociodémographiques, cliniques et les données relatives aux activités de PTME du VIH ont été étudiés. Les statistiques usuelles ont été utilisées pour analyser les résultats. Le seuil de significativité a été fixé à une valeur de p < 0,05. Résultats Le taux de transmission verticale du VIH était de 12,7% (20/157). Il n'y avait pas d'association significative entre les caractéristiques sociodémographiques maternelles telles que l’âge, la parité, le niveau d’étude, la profession et l’état-civil et la TME (p>0,05). La transmission verticale du VIH était significativement associée aux facteurs suivants: le stade clinique 3 de l'OMS (OR=5,18 (1,5-18,1)), la présence d'infection opportuniste (OR=8,7 (2,7-27,8)), le dépistage lors de l'accouchement (OR=6,3 (1,0-39,0)) ou au cours de l'allaitement (OR=7,1 (1,1-76,7)), au taux de CD4 maternel <350/mm3 (OR=2,9 (1,1-7,7)), l'absence de thérapie antirétrovirale chez la mère (OR=19,9 (4,8-81,9)), la naissance avant terme (OR=4,7 (1,4-16,0)), la rupture prématurée de membranes (OR=45,0 (7,4-454,6)), le faible poids de naissance (OR=5,6 (1,9-16,7)), la notion de réanimation néonatale (OR=12,4 (3,8-40,1)), la non administration de la névirapine à la naissance (OR=26,4 (7,6-92,3)) et l'alimentation mixte (OR=12,6 (1,3-115,9)). Le sexe du nourrisson et le mode d'accouchement n’étaient pas non plus associés à la transmission verticale du VIH (p>0,05). Conclusion Le taux

Correlation between the structural distortions and thermoelectric characteristics in La(1-x)A(x)CoO(3) (A = Ca and Sr).

PubMed

Wang, Yang; Sui, Yu; Ren, Peng; Wang, Lan; Wang, Xianjie; Su, Wenhui; Fan, Hong Jin

2010-04-05

Detailed structures and thermoelectric (TE) properties are investigated for the perovskite La(1-x)Ca(x)CoO(3) and La(1-x)Sr(x)CoO(3) with 0 La(1-x)Sr(x)CoO(3) series has smaller global distortions but larger local distortions. The different structural distortions strongly influence the transport and TE properties in terms of resistivity, thermopower, thermal conductivity, bandwidth, and effective mass as well as electronic correlation. These results unambiguously demonstrate a close correlation between the structural distortions and TE characteristics in this family. Furthermore, a new approach is suggested to improve the TE performance by controlling the structure factors in such strongly correlated oxide systems. The effects of the spin-state transition of Co ions on the TE properties are also discussed.

Water electrolysis on La1−xSrxCoO3−δ perovskite electrocatalysts

PubMed Central

Mefford, J. Tyler; Rong, Xi; Abakumov, Artem M.; Hardin, William G.; Dai, Sheng; Kolpak, Alexie M.; Johnston, Keith P.; Stevenson, Keith J.

2016-01-01

Perovskite oxides are attractive candidates as catalysts for the electrolysis of water in alkaline energy storage and conversion systems. However, the rational design of active catalysts has been hampered by the lack of understanding of the mechanism of water electrolysis on perovskite surfaces. Key parameters that have been overlooked include the role of oxygen vacancies, B–O bond covalency, and redox activity of lattice oxygen species. Here we present a series of cobaltite perovskites where the covalency of the Co–O bond and the concentration of oxygen vacancies are controlled through Sr2+ substitution into La1−xSrxCoO3−δ. We attempt to rationalize the high activities of La1−xSrxCoO3−δ through the electronic structure and participation of lattice oxygen in the mechanism of water electrolysis as revealed through ab initio modelling. Using this approach, we report a material, SrCoO2.7, with a high, room temperature-specific activity and mass activity towards alkaline water electrolysis. PMID:27006166

Processus ultra-rapides associés à la dynamique d'émission de la protéine GFP

NASA Astrophysics Data System (ADS)

Didier, P.; Guidoni, L.; Schwalbach, G.; Bigot, J.-Y.

2002-06-01

La protéine GFP (Green Fluorescent Protein) est un marqueur très efficace, utilisable en milieu vivant. La spectroscopie femtoseconde est particulièrement bien adaptée pour comprendre les mécanismes d'émission de cette protéine, étant donné la rapidité des processus de transfert mis en jeu. Nous-présentons des résultats sur la dynamique spectro-temporelle d'émission du mutant GFPuv résolue à l'échelle de la centaine de femtosecondes. Une transition Raman à 3300 cm^{-1} ainsi que la dynamique d'etablissement du gain avec un temps caractéristique d'environ 1.5 ps ont été mis en évidence.

[Diversity of Lactobacillus in vagina of vulvovaginal candidiasis].

PubMed

2015-04-07

To investigate the Lactobacillus species in the vaginas of vulvovaginal candidiasis and to assess the prevalence of each Lactobacillus species in vulvovaginal candidiasis. 154 vaginal samples were analyzed, 92 of which were from fertile healthy women, and 62 of which were from women with vulvovaginal candidiasis; and species-specific PCR showed the prevalence of each Lactobacillus species Species-specific PCR was used to investigate the prevalence of each Lactobacillus species in healthy Chinese women and the women with vulvovaginal candidiasis. In women with vulvovaginal candidiasis: L. iners (6.5%), L. cripatus (79.0%), L. gasseri (37.1%), L. jensenii (74.2%), L. acidophilus (16.1%), L. brevis (19.4%), L. plantarum (1.6%), L. johnsonii (51.6%), L. fermentum (8.1%), L. salivarius (9.7%), L. reuter (1.6%), L. paracasei (8.1%), L. delbrueckii (3. 2% ) ; More than two different Lactobacillus species coexisted in 98% of women with vulvovaginal candidiasis, and no anyone species existed in 2% of them; In fertile women: L. iners (82.6%), L. cripatus (70.7%), L. gasseri (67.4%), L. jensenii (40.2%), L. acidophilus (39.1%), L. brevis (23.9%), L. plantarum (5.4%), L. rhamnosus (1.1%), L. paracasei (1.1%), L. reuter (1.1%) i, L. johnsonii (3.3%), L. fermentum (2.2%), L. salivarius (2.2%); More than two different Lactobacillus species coexisted in 97% of fertile women, and only one species existed in 3% of fertile women. Species of lactobacillus in women with vulvovaginal candidiasis did not significantly reduced compared with healthy women. Lactobacillus inert may be a marker of the change of vaginal microenvironment; Lactobacillus crispatus is a dominant lactobacillus in the vaginal of fertile healthy women, pregnant women and women with vulvovaginal candidiasis.

Size-driven magnetic transitions in La1/3Ca2/3MnO3 nanoparticles

NASA Astrophysics Data System (ADS)

Markovich, V.; Fita, I.; Wisniewski, A.; Mogilyansky, D.; Puzniak, R.; Titelman, L.; Gorodetsky, G.

2010-09-01

Magnetic properties of electron-doped La1/3Ca2/3MnO3 manganite nanoparticles with average particle size ranging from 12 to 42 nm, prepared by the glycine-nitrate method, have been investigated in temperature range 5-300 K and in magnetic fields up to 90 kOe. Reduction in the particle size suppresses antiferromagnetism and decreases the Néel temperature. In contrast to bulk crystals, the charge ordering does not occur in all studied nanoparticles, while a weak ferromagnetism appears above 200 K. Low temperature magnetic hysteresis loops indicate upon exchange bias effect displayed by horizontal and vertical shifts in field cooled processes. The spontaneous and remanent magnetization at low temperature shows a relatively complex variation with particle size. The size-induced structural/magnetic disorder drives the La1/3Ca2/3MnO3 nanoparticles to a pronounced glassy behavior for the smallest 12 nm particles, as evidenced by large difference between zero field cooled and field cooled magnetization, frequency dependent ac-susceptibility, as well as characteristic slowing down in the spin dynamics. Time evolution of magnetization recorded in magnetic fields after field cooling to low temperatures exhibits pronounced relaxation and a very noisy behavior that may be caused by formation of some collective states. Magnetic properties of the nanoparticle samples are compared with those of La0.2Ca0.8MnO3 nanoparticles. These results shed some light on the coupling between charges and spin degrees of freedom in antiferromagnetic manganite nanoparticles.

The hunt for LaFeSbO: Synthesis of La{sub 2}SbO{sub 2} and a case of mistaken identity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muir, Sean, E-mail: muirs@onid.orst.edu; Vielma, Jason, E-mail: vielmaj@onid.orst.edu; Schneider, Guenter, E-mail: guenter.schneider@oregonstate.edu

The phase La{sub 2}SbO{sub 2} has been identified and characterized in the course of our efforts to realize LaFeSbO, a composition of great interest to the superconductor community. The compound La{sub 2}SbO{sub 2} is a tetragonal layered oxypnictide containing La{sub 2}O{sub 2} layers similar to LaMPnO compositions (where M=transition metal, Pn=pnictide) separated by pnictide anion layers. In order to better understand why LaFeSbO has remained elusive, density functional theory calculations have been used to determine the ground state heats of formation for LaFeSbO, La{sub 2}SbO{sub 2}, and other competing phases within the La-Fe-Sb-O system, as well as the phonon spectrummore » for LaFeSbO. These efforts suggest that LaFeSbO is a potentially metastable composition. - Graphical abstract: The layered oxypnictide compounds La{sub 2}SbO{sub 2} and La{sub 1.9}Sr{sub 0.1}SbO{sub 2} have been synthesized and investigated. Both crystallize in a ThCr{sub 2}Si{sub 2} type configuration and are semiconducting. Stability of the unreported compound LaFeSbO has been investigated using density functional theory. A case of mistaken identity in the literature regarding the composition LaNiBiO is addressed. Highlights: Black-Right-Pointing-Pointer The composition La{sub 2}SbO{sub 2} has been identified. Black-Right-Pointing-Pointer La{sub 2}SbO{sub 2} belongs to an unusual group of materials containing Pn{sup 2-} anions. Black-Right-Pointing-Pointer La{sub 2}SbO{sub 2} and La{sub 1.9}Sr{sub 0.1}SbO{sub 2} are both found to be semiconducting. Black-Right-Pointing-Pointer DFT has been used to calculate heats of formation within the La-Fe-Sb-O system. Black-Right-Pointing-Pointer The phonon spectrum for LaFeSbO reveals no unstable lattice mode.« less

Properties of spin-1/2 triangular-lattice antiferromagnets CuY2Ge2O8 and CuLa2Ge2O8

NASA Astrophysics Data System (ADS)

Cho, Hwanbeom; Kratochvílová, Marie; Sim, Hasung; Choi, Ki-Young; Kim, Choong Hyun; Paulsen, Carley; Avdeev, Maxim; Peets, Darren C.; Jo, Younghun; Lee, Sanghyun; Noda, Yukio; Lawler, Michael J.; Park, Je-Geun

2017-04-01

We found new two-dimensional (2D) quantum (S =1 /2 ) antiferromagnetic systems: Cu R E2G e2O8 (R E =Y and La). According to our analysis of high-resolution x-ray and neutron diffraction experiments, the Cu network of Cu R E2G e2O8 (R E =Y and La) exhibits a 2D triangular lattice linked via weak bonds along the perpendicular b axis. Our bulk characterizations from 0.08 to 400 K show that they undergo a long-range order at 0.51(1) and 1.09(4) K for the Y and La systems, respectively. Interestingly, they also exhibit field induced phase transitions. For theoretical understanding, we carried out the density functional theory (DFT) band calculations to find that they are typical charge-transfer-type insulators with a gap of Eg≅2 eV . Taken together, our observations make Cu R E2G e2O8 (R E =Y and La) additional examples of low-dimensional quantum spin triangular antiferromagnets with the low-temperature magnetic ordering.

Magnetic ordering in intermetallic La1-xTbxMn2Si2 compounds

NASA Astrophysics Data System (ADS)

Korotin, Dm. M.; Streltsov, S. V.; Gerasimov, E. G.; Mushnikov, N. V.; Zhidkov, I. S.; Kukharenko, A. I.; Finkelstein, L. D.; Cholakh, S. O.; Kurmaev, E. Z.

2018-05-01

The magnetic structures and magnetic phase transitions in intermetallic layered La1-xTbxMn2Si2 compounds (the ThCr2Si2-type structure) are investigated using the first-principles method and XPS measurements. The experimentally observed transition from ferromagnetic (FM) to antiferromagnetic (AFM) ordering of Mn sublattice with increase of terbium concentration is successfully reproduced in calculations for collinear magnetic moments model. The FM →AFM change of interplane magnetic ordering at small x is irrelevant to the number of f-electrons of the rare-earth ion. In contrast it was shown to be related to the Mn-Mn in-plane distance. Calculated Tb critical concentration for this transition x ≈ 0.14 corresponds to the Mn-Mn in-plane distance 0.289 nm, very close to the experimentally observed transition distance 0.287 nm. The crystal cell compression due to substitution increases an overlap between Mndxz,yz and the rare-earth ion d orbitals. Resulting hybridized states manifest themselves as an additional peak in the density of states. We suggest that a corresponding interlayer Mn-R-Mn superexchange interaction stabilizes AFM magnetic ordering in these compounds with Tb doping level x > 0.2 . The results of DFT calculations are in agreement with X-ray photoemission spectra for La1-xTbxMn2Si2 .

Redox cycling induced Ni exsolution in Gd0.1Ce0.8Ni0.1O2 - (Sr0.9La0.1)0.9Ti0.9Ni0.1O3 composite solid oxide fuel cell anodes

NASA Astrophysics Data System (ADS)

Shen, X.; Chen, T.; Bishop, S. R.; Perry, N. H.; Tuller, H. L.; Sasaki, K.

2017-12-01

Oxide anodes composed of 60 wt% Gd0.1Ce0.8Ni0.1O2 (GDCN)- 40 wt% (Sr0.9La0.1)0.9Ti0.9Ni0.1O3 (SLTN) composites were prepared and tested on (ZrO2)0.89(Sc2O3)0.1(CeO2)0.01 (SSZ) electrolyte-supported SOFC cells utilizing a (La0.75Sr0.25)0.98MnO3 (LSM)-SSZ cathode, in 3%-humidified hydrogen fuel at 800 °C. Improved electrochemical performance was found compared to the cell using Ni-free 60 wt% Gd0.1Ce0.9O2 (GDC) - 40 wt % Sr0.9La0.1TiO3 (SLT) that was attributed to the exsolution of nano-sized Ni particles from the Ni-doped system. This exsolution process represents a simpler, more attractive method to improve performance than the more conventional but more complicated infiltration method for introducing catalytic nanoparticles. Redox cycling testing was performed to investigate the performance and structural stability of the Ni-doped GDC-SLT anode. The results indicated that the Ni exsolution and aggregation occurred while redox cycling proceeded, resulting in a gradually reduced anodic overvoltage. Symmetric cells with dense thin film Gd0.1Ce0.9-xNixO2 (x = 0, 0.05, 0.1, 0.15) electrodes were also tested, demonstrating lower area-specific resistances with increasing Ni content on the surface under reducing conditions. The steady improvement during redox cycling, despite Ni agglomeration, is related to the continuous increase in the overall Ni content on the anode surface, which may be enabled by kinetic limitations to Ni re-dissolving under oxidizing transients.

Abordaje a la Cisterna Ambiens

PubMed Central

Ajler, Pablo; Bravo, Michael Cruz; Garategui, Lucas; Goldschmidt, Ezequiel; Isolan, Gustavo; Campero, Álvaro

2016-01-01

Resumen Objetivo: Describir paso a paso el abordaje a la cisterna ambiens por la vía suboccipital retrosigmoidea supracerebelosa infratentorial (SRSI). Descripción: El abordaje SRSI se realiza de la misma manera que el abordaje suboccipital retrosigmoideo (SR), utilizado habitualmente para acceder a la patología del ángulo pontocerebeloso, con las siguientes modificaciones: (1) utilizamos siempre la posición semisentado, (2) la craneotomia-craniectomia debe exponer el seno transverso y extenderse 5 cm medialmente hacia el inion, (3) al realizar la apertura dural es necesario rebatir la duramadre junto con el seno transverso hacia cefálico con puntos de tracción, (4) bajo magnificación con microscopio quirúrgico se debe realizar la apertura de la cisterna cerebelobulbar para drenar líquido cefalorraquídeo, (5) en el plano supracerebeloso es fundamental cortar las bridas aracnoidales y de ser necesario debemos coagular y cortar las venas puente, todas estas maniobras sumadas al efecto de la gravedad brindan mayor apertura del corredor supracerebeloso. Conclusión: El abordaje a la cisterna ambiens por la vía SRSI es una opción segura para el acceso de patologías tumorales que se alojan en esta zona con un componente predominantemente infratentorial. PMID:27999709

Magnetocaloric effect and the influence of pressure on magnetic properties of La-excess pseudo-binary alloys La{sub 1+δ}(Fe{sub 0.85}Si{sub 0.15}){sub 13}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vuong, Van Hiep; Do Thi, Kim Anh; Thuan Nguyen, Khac

2016-10-14

The La-excess alloys La{sub 1+δ}(Fe{sub 0.85}Si{sub 0.15}){sub 13} (δ = 0.06 and 0.09) exhibit large magnetocaloric effect which has been attributed to the occurrence of itinerant-electron metamagnetic transition near the Curie temperature T{sub C}. The maximum entropy change −ΔS{sub m} was shown to be from 4.5 to 11.5 J/kg K for the applied field variation ΔH from 20 to 70 kOe, respectively. The estimated relative cooling power for ΔH = 70 kOe was 418 J/kg. The alloys show a typical NaZn{sub 13}-type cubic structure, featuring a doping-induced magnetovolume effect with the increase in T{sub C}. Under the applied pressure up to 2 GPa, the T{sub C} asmore » deduced from resistance measurements decreased linearly, ΔT{sub C} = 113 (for δ = 0.06) and 111 K (for δ = 0.09), together with a corresponding decrease of resistivity, Δρ = 6.1 μΩ m at room temperature for both samples. At a low pressure, the effect of spontaneous magnetostriction on T{sub C} caused by applying the pressure appeared to have a similar magnitude to that of the negative magnetovolume effect caused by La-excess doping. In comparison with other stoichiometric La(Fe{sub 1−x}Si{sub x}){sub 13} compounds, the pressure in our case was shown to have a smaller influence on T{sub C}.« less

Reinforcement of double-exchange ferromagnetic coupling by Ru in La{sub 1.24}Sr{sub 1.76}Mn{sub 2-y}Ru{sub y}O{sub 7} manganite system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumaresavanji, M., E-mail: vanji.hplt@gmail.com; Fontes, M.B.; Lopes, A.M.L.

2014-03-01

Highlights: • Effect of Mn-site doping by Ru has been studied in La{sub 1.24}Sr{sub 1.76}Mn{sub 2-y}Ru{sub y}O{sub 7}. • Electrical resistance, magnetoresistance and magnetic properties were measured. • Ru substitution enhances the ferromagnetism and metallicity. • Results were interpreted by the ferromagnetically coupled Ru with Mn ions in Mn–O–Ru network. - Abstract: The effect of Mn-site doping on magnetic and transport properties in the bilayer manganites La{sub 1.24}Sr{sub 1.76}Mn{sub 2-y}Ru{sub y}O{sub 7} (y = 0.0, 0.04, 0.08 and 0.15) has been studied. The undoped compound La{sub 1.24}Sr{sub 1.76}Mn{sub 2}O{sub 7} exhibits a ferromagnetic metal to paramagnetic insulator transition at T{submore » C} = 130 K and the substitution of Ru shifts the transition temperatures to higher temperature values. The increased metal–insulator transition by Ru substitution, obtained from temperature dependence of resistivity measurements, indicates that the Ru substitution enhances the metallic state at low temperature regime and favours the Mn–Ru pairs in the Ru doped samples. Moreover, the activation energy values calculated from the temperature dependence of resistivity curves suggest that the Ru substitution weakens the formation of polarons. The increased magnetoresistance ratio from 108% to 136% by Ru substitution, measured at 5 K, points out that the Ru substitution also enhances the inter-grain tunneling magnetoresistance. Thus, the ferromagnetic order and metallic state in La{sub 1.24}Sr{sub 1.76}Mn{sub 2}O{sub 7} system have been enhanced by the presence of Ru in the Mn-site. These reinforcements of ferromagnetic metallic state and magnetoresistance have been interpreted by the ferromagnetically coupled high spin states of Ru with Mn ions in the Mn–O–Ru network.« less

Magnetic phase diagrams of CexLa1-xB6 in high magnetic fields

NASA Astrophysics Data System (ADS)

Akatsu, Mitsuhiro; Kazama, Nanako; Goto, Terutaka; Nemoto, Yuichi; Suzuki, Osamu; Kido, Giyuu; Kunii, Satoru

We have performed ultrasonic measurements under high magnetic fields up to 30 T by using the hybrid magnet at the National Institute for Materials Science to investigate the magnetic phase diagram for antiferroquadrupole (AFQ) phase II in CexLa1-xB6. With increasing Ce concentration x from x=0.50, the AFQ phase transition temperatures TQ indicate an almost linear increase in various fields. The large magnetic anisotropy of AFQ phase II, in which TQH∥[0 0 1] is much smaller than TQH∥[1 1 0] and TQH∥[1 1 1] in high magnetic fields, is revealed in x=0.75,0.60 as well as in x=0.50. These experimental results support the theoretical calculation based on the Γ5-type AFQ ordering and the magnetic field induced octupole Txyz.

AtLa1 protein initiates IRES-dependent translation of WUSCHEL mRNA and regulates the stem cell homeostasis of Arabidopsis in response to environmental hazards.

PubMed

Cui, Yuchao; Rao, Shaofei; Chang, Beibei; Wang, Xiaoshuang; Zhang, Kaidian; Hou, Xueliang; Zhu, Xueyi; Wu, Haijun; Tian, Zhaoxia; Zhao, Zhong; Yang, Chengwei; Huang, Tao

2015-10-01

Plant stem cells are hypersensitive to environmental hazards throughout their life cycle, but the mechanism by which plants safeguard stem cell homeostasis in response to environmental hazards is largely unknown. The homeodomain transcription factor WUSCHEL (WUS) protein maintains the stem cell pool in the shoot apical meristem of Arabidopsis. Here, we demonstrate that the translation of WUS mRNA is directed by an internal ribosomal entry site (IRES) located in the 5'-untranslated region. The AtLa1 protein, an RNA-binding factor, binds to the 5'-untranslated region and initiates the IRES-dependent translation of WUS mRNA. Knockdown of AtLa1 expression represses the WUS IRES-dependent translation and leads to the arrest of growth and development. The AtLa1 protein is mainly located in the nucleoplasm. However, environmental hazards promote the nuclear-to-cytoplasmic translocation of the AtLa1 protein, which further enhances the IRES-dependent translation of WUS mRNA. Genetic evidence indicates that the WUS protein increases the tolerance of the shoot apical meristem to environmental hazards. Based on these results, we conclude that the stem cell niche in Arabidopsis copes with environmental hazards by enhancing the IRES-dependent translation of WUS mRNA under the control of the AtLa1 protein. © 2015 John Wiley & Sons Ltd.

TENDENCIA DE LA TUBERCULOSIS EN LA REGIÓN SANITARIA V DE LA PROVINCIA DE BUENOS AIRES, AÑOS 2000–2011

PubMed Central

CHIRICO, CRISTINA; SANJURJO, MYRIAM; IRIBARREN, SARAH; APPENDINO, ANDREA; ZERBINI, ELSA; ETCHEVARRIA, MIRTA

2016-01-01

El objetivo del presente trabajo fue analizar la situación epidemiológica de la tuberculosis (TB) en la Región Sanitaria V (RSV), provincia de Buenos Aires. El estudio de tendencia permitió conocer un valor promedio de las variaciones de la tasa de incidencia (TI), calculadas por regresión lineal simple y expresadas como variación anual promedio (VAP). Se analizaron el número de casos notificados y TI por 100 000 habitantes de todas las formas de TB, los casos de TB pulmonar (TBP) y TBP confirmados por bacteriología, total casos por grupos de edad: 0 – 14; 15 – 29 y mayores de 64 años, entre el 1° de enero de 2000 al 31 de diciembre de 2011. La declinación de la TI fue menor al 5% para todas las formas de TB e inferior en las TBP confirmadas bacteriológicamente. Los casos de TBP y TI más elevadas, se concentraron en el grupo de 15 a 29 años, con tendencia estable o ligeramente ascendente de la TI en la TBP bacilífera. El mismo comportamiento presentaron los casos de TBP infantil con confirmación bacteriológica. La mayor velocidad de descenso en la TI de la TBP se produjo en este grupo de edad, mientras que en mayores de 64 años, el descenso fue sostenido en el tiempo. La TB persiste como un riesgo de salud en la RSV, con casos en edades jóvenes, por lo que sigue siendo necesario fortalecer el control de la TB en esta región. PMID:26117604

Desarrollo y validación de una nueva tecnología, basada en arginina al 1.5%, un compuesto de calcio insoluble y fluoruro, para el uso diario en la prevención y tratamiento de la caries dental.

PubMed

Cummins, D

2013-10-22

este artículo discute brevemente la prevalencia de caries, la naturaleza multifactorial de su etiología, el riesgo de caries y el papel y eficacia del fluoruro. Resalta también la investigación sobre el metabolismo bacteriano, que ha aportado conocimientos sobre la defensa natural oral contra la caries y la base para el desarrollo de una nueva tecnología para la prevención diaria y el tratamiento de la caries. Por último, se resume la evidencia que respalda que la tecnología complementa y mejora la eficacia anti-caries de la crema dental con fluoruro. los datos globales muestran que a pesar de la exitosa introducción del fluoruro, la caries dental es una enfermedad prevalente. La experiencia de caries depende del balance entre el consumo de azúcares, la higiene oral y el uso del fluoruro. Hay tres conceptos científicos que son fundamentales en las nuevas mediciones para detectar, tratar y monitorear la caries: (1) la caries dental es un proceso dinámico, (2) la caries dental es un proceso continuo de etapas que van desde reversible (pre-clínica) hasta irreversible (lesiones clínicamente detectables), y (3) el proceso de la caries es un balance de factores patológicos y protectores que pueden modularse para el manejo de la caries. El fluoruro funciona como factor protector al detener y revertir el proceso de la caries, pero el fluoruro no previene los factores patológicos que inician el proceso. Se ha identificado una tecnología novedosa, basada en arginina y un compuesto insoluble de calcio, que está dirigida a la placa dental para prevenir la iniciación del proceso de caries al reducir los factores patológicos. Como los mecanismos de acción de la arginina y el fluoruro son altamente complementarios, se ha desarrollado un nuevo dentífrico que combina la arginina y el fluoruro, y se ha probado clínicamente que brinda una prevención superior contra la caries. Copyright © 2013 Elsevier Ltd. All rights reserved.

The small molecule CS1 inhibits mitosis and sister chromatid resolution in HeLa cells.

PubMed

Wu, Xingkang; Li, Zhenyu; Shen, Yuemao

2018-05-01

Mitosis, the most dramatic event in the cell cycle, involves the reorganization of virtually all cellular components. Antimitotic agents are useful for dissecting the mechanism of this reorganization. Previously, we found that the small molecule CS1 accumulates cells in G2/M phase [1], but the mechanism of its action remains unknown. Cell cycle analysis, live cell imaging and nuclear staining were used. Chromosomal morphology was detected by chromosome spreading. The effects of CS1 on microtubules were confirmed by tubulin polymerization, colchicine tubulin-binding, cellular tubulin polymerization and immunofluorescence assays and by analysis of microtubule dynamics and molecular modeling. Histone phosphoproteomics was performed using mass spectrometry. Cell signaling cascades were analyzed using immunofluorescence, immunoprecipitation, immunoblotting, siRNA knockdown and chemical inhibition of specific proteins. The small molecule CS1 was shown to be an antimitotic agent. CS1 potently inhibited microtubule polymerization via interaction with the colchicine-binding pocket of tubulin in vitro and inhibited the formation of the spindle apparatus by reducing the bulk of growing microtubules in HeLa cells, which led to activation of the spindle assembly checkpoint (SAC) and mitotic arrest of HeLa cells. Compared with colchicine, CS1 impaired the progression of sister chromatid resolution independent of cohesin dissociation, and this was reversed by the removal of CS1. Additionally, CS1 induced unique histone phosphorylation patterns distinct from those induced by colchicine. CS1 is a unique antimitotic small molecule and a powerful tool with unprecedented value over colchicine that makes it possible to specifically and conditionally perturb mitotic progression. Copyright © 2018 Elsevier B.V. All rights reserved.

Interface energetics and atomic structure of epitaxial La{sub 1−x}Sr{sub x}CoO{sub 3} on Nb:SrTiO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Overmeere, Quentin, E-mail: quentin.vanovermeere@uclouvain.be, E-mail: john.d.baniecki@jp.fujitsu.com; Baniecki, John D., E-mail: quentin.vanovermeere@uclouvain.be, E-mail: john.d.baniecki@jp.fujitsu.com; Yamazaki, Takashi

2015-06-15

The energetics at oxide semiconductor/La{sub 1−x}Sr{sub x}CoO{sub 3} heterojunctions, including the respective alignment of the valence and conduction bands, govern charge transfer and have to be determined for the design of future La{sub 1−x}Sr{sub x}CoO{sub 3}-based devices. In this letter, the electronic and atomic structures of epitaxial La{sub 1−x}Sr{sub x}CoO{sub 3} on Nb-doped strontium titanate are revealed by scanning transmission electron microscopy, electron energy loss spectroscopy, and in situ x-ray and ultra violet photoelectron spectroscopies. For LaCoO{sub 3}, a valence band (VB) offset of 2.8 ± 0.1 eV is deduced. The large offset is attributed to the orbital contributions of the Co 3dmore » states to the VB maximum of the LaCoO{sub 3} thin films, with no evidence of interface dipole contributions. The sensitivity of the valence band orbital character to spin state ordering and oxygen vacancies is assessed using density functional theory.« less

Metabolic control and treatment patterns in patients with type 1 diabetes in Castilla-La Mancha: the DIAbetes tipo 1 in Castilla La Mancha study.

PubMed

Sastre, Julia; Pinés, Pedro José; Moreno, Jesús; Aguirre, Miguel; Blanco, Benito; Calderón, Dulce; Herranz, Sandra; Roa, Carlos; Lopez, José

2012-11-01

To assess glycemic control, the degree of control of cardiovascular risk factors, and treatment schemes used in patients with type 1 diabetes mellitus (T1DM) in Castilla-La Mancha (Spain). A cross-sectional, multicenter study on adult patients with T1DM seen at outpatient endocrinology clinics for 12 months (from September 2009 to August 2010). Diabetes duration was > 5 years in all cases. Sociodemographic, clinical, anthropometric, and laboratory variables were collected, as well as treatment data. A multivariate logistic regression analysis was used to assess variables independently associated to good glycemic control. A total of 1465 patients (48.5% women) with a mean age of 39.4±13.5 years and a mean diabetes duration of 19.4±10.6 years, were enrolled. Mean glycosylated hemoglobin (HbA1c) level was 7.8%, and 26% had HbA1c values ≤7%. Predictors of good glycemic control (HBA1c ≤7%) included intensive insulin treatment [odds ratio (OR): 2.56], non-smoking status (OR: 1.66), and a higher educational level (OR: 1.33). Fifteen percent of patients were obese, 35% had dyslipidemia, 23% were hypertensive, and 26% smoked. Four or more of the recommended control goals were achieved by 68% of patients, but more than 33% required additional drug treatment. Glycemic control was inadequate in this cohort of T1DM patients. Promotion of healthy attitudes and intensification of insulin treatment may improve glycemic control. Prevalence of cardiovascular risk factors is high, although a great proportion of patients achieve good lipid and blood pressure control. Copyright © 2012 SEEN. Published by Elsevier Espana. All rights reserved.

Structural and impedance spectroscopy properties of La0.8Ba0.1Ca0.1Mn1-xRuxO3 perovskites

NASA Astrophysics Data System (ADS)

Chebaane, M.; Talbi, N.; Dhahri, A.; Oumezzine, M.; Khirouni, K.

2017-03-01

Polycrystalline samples La0.8Ba0.1Ca0.1Mn1-xRuxO3 (x=0 and 0.075) were prepared by sol-gel-based Pechini method. The X ray diffraction study has shown that all the samples exhibit a single phase with rhombohedral structure (space group R 3 ̅c, no. 167). The complex impedance has been investigated in the temperature range 160-320 K and in the frequency range 40 Hz-1 MHz. The imaginary part of the complex impedance (Z‧‧) frequency dependence revealed one relaxation peak. The Cole-Cole plots of the impedance values exhibited a semi -circular arc that can be described by an R1+(R2//ZCPE) electrical equivalent circuit. The conductance spectra have been investigated by the Jonscher universal power law: G(ω)=GDC+Aωn, where ω is the frequency of the ac field, and n is the exponent. The activation energy obtained both from the conductance and from time relaxation analyses are very similar, and hence the relaxation process may be attributed to the same type of charge carriers.

Band-gap engineering of La1-x Nd x AlO3 (x = 0, 0.25, 0.50, 0.75, 1) perovskite using density functional theory: A modified Becke Johnson potential study

NASA Astrophysics Data System (ADS)

Sandeep; D, P. Rai; A, Shankar; M, P. Ghimire; Anup Pradhan, Sakhya; T, P. Sinha; R, Khenata; S, Bin Omran; R, K. Thapa

2016-06-01

The structural, electronic, and magnetic properties of the Nd-doped Rare earth aluminate, La1-x Nd x AlO3 (x = 0% to 100%) alloys are studied using the full potential linearized augmented plane wave (FP-LAPW) method within the density functional theory. The effects of the Nd substitution in LaAlO3 are studied using the supercell calculations. The computed electronic structure with the modified Becke-Johnson (mBJ) potential based approximation indicates that the La1-x Nd x AlO3 alloys may possess half-metallic (HM) behaviors when doped with Nd of a finite density of states at the Fermi level (E F). The direct and indirect band gaps are studied each as a function of x which is the concentration of Nd-doped LaAlO3. The calculated magnetic moments in the La1-x Nd x AlO3 alloys are found to arise mainly from the Nd-4f state. A probable half-metallic nature is suggested for each of these systems with supportive integral magnetic moments and highly spin-polarized electronic structures in these doped systems at E F. The observed decrease of the band gap with the increase in the concentration of Nd doping in LaAlO3 is a suitable technique for harnessing useful spintronic and magnetic devices. Project supported by the DST-SERB, Dy (Grant No. SERB/3586/2013-14), the UGCBSR, FRPS (Grant No. F.30-52/2014), the UGC (New Delhi, India) Inspire Fellowship DST (India), and the Deanship of Scientific Research at King Saud University (Grant No. RPG-VPP-088). M P Ghimire thanks the Alexander von Humboldt Foundation, Germany for the financial support.

Modulated visible spectra properties of Pr:Ca1-xRxF2+x(R=Y, La, Gd) crystals

NASA Astrophysics Data System (ADS)

Yu, Hao; Qian, Xiaobo; Wu, Qinghui; Ma, Fengkai; Wang, Jingya; Xu, Jun; Su, Liangbi

2017-10-01

The spectroscopic properties of the 1.0 at.%Pr:Ca0.97R0.02F2.03(R=Y, La, Gd) crystals are investigated. X-diffraction and room temperature absorption spectra have been registered and analyzed. The emission spectra and decay curves of the crystals were obtained at room temperature. The photoluminescence intensity in the visible region is significantly enhanced by co-doping R3+ ions in Pr:CaF2 crystal. The different effects among the R3+ (Y3+, La3+ and Gd3+) regulating ions on the crystals were observed and compared. Pr:Ca0.97La0.02F2.03 and Pr:Ca0.97Y0.02F2.03 crystals have substantially strong emission at blue and orange region, while the Pr:Ca0.97Gd0.02F2.03 crystal is more suitable for the red emission emitting.

C1 Domain-Targeted Isophthalate Derivatives Induce Cell Elongation and Cell Cycle Arrest in HeLa Cells

PubMed Central

Talman, Virpi; Tuominen, Raimo K.; Gennäs, Gustav Boije af; Yli-Kauhaluoma, Jari; Ekokoski, Elina

2011-01-01

Diacylglycerol (DAG)-mediated signaling pathways, such as those mediated by protein kinase C (PKC), are central in regulating cell proliferation and apoptosis. DAG-responsive C1 domains are therefore considered attractive drug targets. Our group has designed a novel class of compounds targeted to the DAG binding site within the C1 domain of PKC. We have previously shown that these 5-(hydroxymethyl)isophthalates modulate PKC activation in living cells. In this study we investigated their effects on HeLa human cervical cancer cell viability and proliferation by using standard cytotoxicity tests and an automated imaging platform with machine vision technology. Cellular effects and their mechanisms were further characterized with the most potent compound, HMI-1a3. Isophthalate derivatives with high affinity to the PKC C1 domain exhibited antiproliferative and non-necrotic cytotoxic effects on HeLa cells. The anti-proliferative effect was irreversible and accompanied by cell elongation. HMI-1a3 induced down-regulation of retinoblastoma protein and cyclins A, B1, D1, and E. Effects of isophthalates on cell morphology, cell proliferation and expression of cell cycle-related proteins were different from those induced by phorbol 12-myristate-13-acetate (PMA) or bryostatin 1, but correlated closely to binding affinities. Therefore, the results strongly indicate that the effect is C1 domain-mediated. PMID:21629792

A high pressure La K-edge X-ray absorption fine structure spectroscopy investigation of La1/3NbO3

NASA Astrophysics Data System (ADS)

Marini, C.; Joseph, B.; Noked, O.; Shuker, R.; Kennedy, B. J.; Mathon, O.; Pascarelli, S.; Sterer, E.

2018-01-01

La K-edge X-ray absorption spectroscopy has been used to elucidate the changes in the local electronic and lattice structure that occur in the A-site deficient double perovskite La?NbO? up to 6 GPa. The pressure evolution of the oxygen dodecahedrum around the A-site has been examined. XANES (X-ray absorption near edge structure) data show modifications ascribed to the increase of bands overlapping as a consequence of the bond distance contraction, which has been directly probed by EXAFS (extended x-ray absorption fine structure) spectra. The La-O Debye Waller factors (DWFs) tend to increase whereas the La-Nb bond DWFs show only a tendency to decrease indicating the robustness of the crystal lattice structure, even in presence of the oxygen disordering. This permits the system to reverse back to its original conditions in this pressure range as evident from the measurements upon pressure release. The present results have been interpreted in the light of charge transfer related to the two-step reduction mechanism acting at the Nb site (with niobium ions passing from Nb? to Nb?) which also results in the elongation of the Nb-O bond distances in the octahedra, in agreement with the Nb K-edge results reported earlier.

Lattice thermal expansion of the solid solutions (La{sub 1−x}Sm{sub x}){sub 2}Ce{sub 2}O{sub 7}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Hongdan; Lei, Xinrong; Zhang, Jinhua, E-mail: jhzhang1212@126.com

2014-09-15

Highlights: • Sm-doped La{sub 2}Ce{sub 2}O{sub 7} was prepared by the coprecipitation–calcination method. • In situ HT-XRD measurements revealed that is much stable than 8YSZ. • Its thermal expansion is better than 8YSZ. - Abstract: A series of solid solutions with the general formula (La{sub 1−x}Sm{sub x}){sub 2}Ce{sub 2}O{sub 7} (0.0 ≤ x ≤ 1.0) were prepared by the coprecipitation–calcination method. The products obtained were characterized by powder X-ray diffraction for phase purity. It was observed that La{sup 3+} and Sm{sup 3+} can form complete solid solution in (La,Sm){sub 2}Ce{sub 2}O{sub 7} with defect-fluorite-type phase. The unit cell parameters ofmore » these solutions were calculated by a least squares method and the lattice parameters decreased linearly as x increased. The lattice thermal expansion behavior of (La{sub 1−x}Sm{sub x}){sub 2}Ce{sub 2}O{sub 7} (0.0 ≤ x ≤ 1.0) was investigated by high-temperature X-ray diffraction in the temperature range 298–1623 K. The lattice parameters a{sub T} of all the solutions at different temperature can be expressed as a{sub T} = a + bT + cT{sup 2}. As x < 1, the thermal expansion has a sudden decrease at ca. 473 K. The coefficients of lattice thermal expansion of Sm{sub 2}Ce{sub 2}O{sub 7} were 10.2–13.6 × 10{sup −6} K{sup −1} from 298 to 1623 K, and without the thermal contraction at low temperature. The materials show positive or negative thermal expansion due to the asymmetric anharmonic vibration.« less

Enhanced ferromagnetism, metal-insulator transition, and large magnetoresistance in La1-xCaxMn1-xRuxO3 free of eg-orbital double-exchange

NASA Astrophysics Data System (ADS)

Liu, M. F.; Du, Z. Z.; Liu, H. M.; Li, X.; Yan, Z. B.; Dong, S.; Liu, J.-M.

2014-03-01

The structure, ionic valences, magnetism, and magneto-transport behaviors of mixed valence oxides La1-xCaxMn1-xRuxO3 are systematically investigated. The simultaneous substitutions of La3+ and Mn3+ ions by Ca2+ and Ru4+, respectively, are confirmed by the structural and ionic valence characterizations, excluding the presence of Mn4+ and Ru3+ ions. The enhanced ferromagnetism, induced metal-insulator transition, and remarkable magnetoresistance effect are demonstrated when the substitution level x is lower than ˜0.6, in spite of the absence of the Mn3+-Ru4+ eg-orbital double-exchange. These anomalous magnetotransport effects are discussed based on the competing multifold interactions associated with the Mn3+-Ru4+ super-exchange and strong Ru4+-Ru4+ hopping, while the origins for the metal-insulator transition and magnetoresistance effect remain to be clarified.

Electronic and magnetic properties in Sr{sub 1-x}La{sub x}RuO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Renu; Pramanik, A. K., E-mail: akpramanik@mail.jnu.ac.in

2016-05-23

Here we report the structural, magnetic and transport properties in La doped SrRuO{sub 3}. The doping of La{sup 3+} modifies the ionic state of Ru by converting Ru{sup 4+} to Ru{sup +3}. However, there is modification in lattice parameters as La{sup 3+} has smaller ionic radii than that of Sr{sup 2+}. We find La doping weakens the ferromagnetic state in SrRuO{sub 3} in terms of lowering T{sub c} and decreasing the magnetic moment. The electrical resistivity shows metallic behavior in whole temperature range, however, resistivity increases with doping of La.

Structural and mechanical properties of lanthanide doped La1/3Nb0.8Ta0.2O3 thin films prepared by sol-gel method

NASA Astrophysics Data System (ADS)

Brunckova, Helena; Medvecky, Lubomir; Kovalcikova, Alexandra; Fides, Martin; Mudra, Erika; Durisin, Juraj; Skvarla, Jiri; Kanuchova, Maria

2017-04-01

Transparent Eu and Nd doped lanthanum niobate tantalate La1/3Nb0.8Ta0.2O3 (LNT) thin films (˜150 nm) were prepared by sol-gel/spin-coating process on Pt/SiO2/Si substrates and annealing at 1100 °C. The x-ray diffraction analysis of films confirmed formation of the perovskite La1/3NbO3 and La1/3TaO3 phases with traces of pyrochlore LaNbO4. Eu and Nd doped LNT films were smoother with roughness 17.1 and 25.4 nm in comparison with LNT (43.3 nm). In all films was observed heterogeneous microstructure with the perovskite spherical and pyrochlore needle-like particles. The mechanical properties of films were characterized for the first time by conventional and continuous stiffness (CSM) nanoindentation. The Eu and Nd doped LNT film modulus (E) and hardness (H) were higher than LNT (˜99.8 and 4.4 GPa) determined by conventional nanoindentation. It was measured the significant effect of substrate on properties of Eu or Nd films (H ˜ 5.9 or 4.9 GPa and E ˜ 107.3 or 104.1 GPa) by CSM nanoindentation.

Lactobacillus rodentium sp. nov., from the digestive tract of wild rodents.

PubMed

Killer, J; Havlík, J; Vlková, E; Rada, V; Pechar, R; Benada, O; Kopečný, J; Kofroňová, O; Sechovcová, H

2014-05-01

Three strains of regular, long, Gram-stain-positive bacterial rods were isolated using TPY, M.R.S. and Rogosa agar under anaerobic conditions from the digestive tract of wild mice (Mus musculus). All 16S rRNA gene sequences of these isolates were most similar to sequences of Lactobacillus gasseri ATCC 33323T and Lactobacillus johnsonii ATCC 33200T (97.3% and 97.2% sequence similarities, respectively). The novel strains shared 99.2-99.6% 16S rRNA gene sequence similarities. Type strains of L. gasseri and L. johnsonii were also most related to the newly isolated strains according to rpoA (83.9-84.0% similarities), pheS (84.6-87.8%), atpA (86.2-87.7%), hsp60 (89.4-90.4%) and tuf (92.7-93.6%) gene sequence similarities. Phylogenetic studies based on 16S rRNA, hsp60, rpoA, atpA and pheS gene sequences, other genotypic and many phenotypic characteristics (results of API 50 CHL, Rapid ID 32A and API ZYM biochemical tests; cellular fatty acid profiles; cellular polar lipid profiles; end products of glucose fermentation) showed that these bacterial strains represent a novel species within the genus Lactobacillus. The name Lactobacillus rodentium sp. nov. is proposed to accommodate this group of new isolates. The type strain is MYMRS/TLU1T (=DSM 24759T=CCM 7945T).

Identification of Lactobacillus strains of goose origin using MALDI-TOF mass spectrometry and 16S-23S rDNA intergenic spacer PCR analysis.

PubMed

Dec, Marta; Urban-Chmiel, Renata; Gnat, Sebastian; Puchalski, Andrzej; Wernicki, Andrzej

2014-04-01

The objective of our study was to identify Lactobacillus sp. strains of goose origin using MALDI-TOF mass spectrometry, ITS-PCR and ITS-PCR/RFLP. All three techniques proved to be valuable tools for identification of avian lactobacilli and produced comparable classification results. Lactobacillus strains were isolated from 100% of geese aged 3 weeks to 4 years, but from only 25% of chicks aged 1-10 days. Among the 104 strains isolated, we distinguished 14 Lactobacillus species. The dominant species was Lactobacillus salivarius (35.6%), followed by Lactobacillus johnsonii (18.3%), Lactobacillus ingluviei (11.5%) and Lactobacillus agilis (7.7%). The intact-cell MALDI-TOF mass spectrometry enabled rapid species identification of the lactobacilli with minimal pretreatment. However, it produced more than one identification result for 11.5% examined strains (mainly of the species L. johnsonii). ITS-PCR distinguished 12 genotypes among the isolates, but was not able to differentiate closely related strains, i.e. between Lactobacillus amylovorus and Lactobacillus kitasatonis and between Lactobacillus paracasei, Lactobacillus rhamnosus and Lactobacillus zeae. These species were differentiated by ITS-PCR/RFLP using the restriction enzymes TaqI and MseI. The results obtained indicate that ITS-PCR and ITS-PCR/RFLP assays could be used not only for interspecific, but also for intraspecific, typing. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

The effects of different heat treatment annealing on structural properties of LaFe11.5Si1.5 compound

NASA Astrophysics Data System (ADS)

Norizan, Yang Nurhidayah Asnida; Din, Muhammad Faiz Md; Zamri, Wan Fathul Hakim W.; Hashim, Fakroul Ridzuan; Jusoh, Mohd Taufik; Rahman, Mohd Rashid Abdul

2018-02-01

The cubic NaZn13-type LaFe13-xSix based compounds have been studied systematically and has become one of the most interesting systems for exploring large MCE. Its magnetic properties are strongly doping dependent and provides many of advantage compare to other as magnetic materials for magnetic refrigerator application. In other to produce high quality of cubic NaZn13-type structure, the structural properties of LaFe11.5Si1.5 compounds annealed at different temperature have been investigated. The LaFe11.5Si1.5 compounds was prepared by arc melting and annealed at two different heat treatment which are 1323 K for 14 days and 1523 K for 4 hour. The powder X-ray diffraction (XRD) shows that a short time and high temperature annealing process has benefits for the formation of the NaZn13-type phase compared to a long time and low temperature annealing process. This is shown by the weight fraction of cubic NaZn13- type structure increases from 80% for low temperature annealing to 83% for high temperature annealing. At the same time, high temperature annealing increase the main structure and decrease the impurity (α-Fe and LaFeSi). Furthermore, it can be clearly seen in the Rietveld refinement results that the lattice parameter is increase at the high temperature annealing because of more cubic NaZn13 is formed at higher temperature.

Growth of langasite via Bridgman technique along [ 0 0 0 1], [ 2 1¯ 1¯ 0] and [ 0 1 1¯ 1] for piezoelectric applications

NASA Astrophysics Data System (ADS)

Uda, Satoshi; Inaba, Hitoshi; Harada, Jiro; Hoshikawa, Keigo

2004-10-01

2-inch langasite (La 3Ga 5SiO 14) single crystals were grown for the first time via a vertical Bridgman method, assisted by the accelerated crucible rotation technique (ACRT) along [ 0 0 0 1] ( Z-axis), [ 2 1¯ 1¯ 0] ( X-axis) and [ 0 1 1¯ 1] (54°-rotated Y-axis) for piezoelectric applications. Because of the possible liquid immiscibility, incongruency and segregation, secondary phases other than langasite are formed during growth. The mode of occurrence of these phases was closely related to the interface instability that was specific to the growth direction. The formation of inclusions consisting of lanthanum gallate (LaGaO 3), aligned parallel to ( 0 1 1¯ 0), was associated with the constitutional supercooling. The residual products during the terminal transient were the mixture of gallium oxide (Ga 2O 3) and lanthanum gallate (LaGaO 3) or the mixture of gallium oxide and lanthanum silicate (La 2Si 2O 7) reflecting the position of the initial melt, relative to the tie line connecting the langasite solid solution with gallium oxide in the system of La 2O 3-Ga 2O 3-SiO 2. The homogeneity of the grown crystal was evaluated by the distribution of SAW velocities of the devices fabricated on the ( 0 1 1¯ 0) wafer, as well as by the uniformity of d-spacing of 0 5 5¯ 5.

Influence of oxygen vacancies on the magnetic and electrical properties of La1-xSrxMnO3-x/2 manganites

NASA Astrophysics Data System (ADS)

Trukhanov, S. V.; Lobanovski, L. S.; Bushinsky, M. V.; Khomchenko, V. A.; Pushkarev, N. V.; Troyanchuk, I. O.; Maignan, A.; Flahaut, D.; Szymczak, H.; Szymczak, R.

2004-11-01

The crystal structure, magnetization and electrical transport depending on the temperature and magnetic field for the doped stoichiometric La_{1-x}^{3 + } Sr_x^{2 + } Mn_{1-x}^{3 + } Mn_x^{4 + } O_3^{2-} as well as anion-deficient La_{1-x}^{3 + } Sr_x^{2 + } Mn^{3 + }O_{3-x/2}^{2-} (0le x le 0.30) ortomanganite systems have been experimentally studied. It is established that the stochiometric samples in the region of the 0 le x le 0.125 are an O'-orthorhombic perovskites whereas in the 0.175 le x le 0.30 - a rhombohedric. For the anion-deficient system the symmetry type of the unit cell is similar to the stoichiometric one. As a doping level increases the samples in the ground state undergo a number of the magnetic transitions. It is assumed that the samples with the large amount of oxygen vacancies are a cluster spin glasses (0.175 < x le 0.30) and temperature of the magnetic moment freezing is 40 K. All the anion-deficient samples are semiconductors and show considerable magnetoresistance over a wide temperature range with a peak for the x = 0.175 only. Concentration dependences of the spontaneous magnetization and magnetic ordering temperature for the anion-deficient La_{1-x}^{3 + } Sr_x^{2 + } Mn^{3 + }O_{3-x/2}^{2-} system have been established by the magnetic measurements and compared with those for the stoichiometric La_{1-x}^{3 + } Sr_x^{2 + } Mn_{1-x}^{3 + } Mn_x^{4 + } O_3^{2-} one. The magnetic propeprties of the anion-deficient samples may be interpreted on the base of the superexchange interaction and phase separation (chemical disorder) models.

Novel anticancer agent, benzyldihydroxyoctenone, isolated from Streptomyces sp. causes G1 cell cycle arrest and induces apoptosis of HeLa cells.

PubMed

Lee, Chul-Hoon; Lim, Haeyoung; Moon, Sangik; Shin, Choonshik; Kim, Seunghyun; Kim, Bum-Joon; Lim, Yoongho

2007-06-01

In the course of screening for anticancer agents, a novel active compound, F3-2-5, was isolated from culture broth of Streptomyces sp., KACC91015. Its structure was identified using nuclear magnetic resonance, mass spectrometry, and molecular modeling experiments, and confirmed by total synthesis. The growth of various human cancer cell lines was inhibited in a dose-dependent manner by 0.06-0.48 mM F3-2-5 over 24 h. Its IC(50) values were estimated at 37 microM on HeLa, 72 microM on A549, and 190 microM on HT-29 cells. However, F3-2-5 had no antiproliferative effect on normal lymphocytes and normal fibroblasts used as controls. Moreover, it affected cell cycle regulation and caused apoptosis of the HeLa cells; chromatin condensation and DNA fragmentation were observed in cells exposed to 80 microM F3-2-5. Western blot analysis revealed that F3-2-5 inhibited phosphorylation of retinoblastoma protein (pRb) and reduced expression of cyclin-dependent kinase-4 and -6, and cyclin D1 and E, while levels of p53 and p21(WAF1/CIP1) increased. Taken together, these findings show that F3-2-5 inhibits proliferation of HeLa cells by inducing G(1) phase arrest as a consequence of inhibition of pRb phosphorylation following up-regulation of p21(WAF1/CIP1) and p53. Furthermore, apoptosis in HeLa cells treated with F3-2-5 was associated with an increase in Bax and p53, leading to release of cytochrome c, activation of caspase-3, and -8, and cleavage of poly (ADP-ribose) polymerase.

Soft ferromagnetism in mixed valence Sr(1-x)La(x)Ti(0.5)Mn(0.5)O₃ perovskites.

PubMed

Qasim, Ilyas; Blanchard, Peter E R; Kennedy, Brendan J; Ling, Chris D; Jang, Ling-Yun; Kamiyama, Takashi; Miao, Ping; Torii, Shuki

2014-05-14

The structural, magnetic and electrical properties of the mixed Ti-Mn oxides Sr(1-x)La(x)Ti(0.5)Mn(0.5)O3 (0 ≤ x ≤ 0.5) are reported. At room temperature the oxides have a cubic structure in space group Pm3m for x ≤ 0.25 and rhombohedral in R3c for 0.3 ≤ x ≤ 0.50. X-ray absorption spectroscopic measurements demonstrate the addition of La(3+) is compensated by the partial reduction of Mn(4+) to Mn(3+). Variable temperature neutron diffraction measurements show that cooling Sr(0.6)La(0.4)Ti(0.5)Mn(0.5)O3 results in a first order transition from rhombohedra to an orthorhombic structure in Imma. Complex magnetic behaviour is observed. The magnetic behaviour of the mixed valent (Mn(3+/4+)) examples is dominated by ferromagnetic interactions, although cation disorder frustrates long range magnetic ordering.

Cation deficient layered Ruddlesden-Popper-related oxysulfides La2LnMS2O5 (Ln=La, Y; M=Nb, Ta).

PubMed

Cario, Laurent; Popa, Aurelian Florin; Lafond, Alain; Guillot-Deudon, Catherine; Kabbour, Houria; Meerschaut, A; Clarke, Simon J; Adamson, Paul

2007-11-12

The structures of the new oxysulfide Ruddlesden-Popper phases La2LnMS2O5 (Ln=La, Y; M=Nb, Ta) are reported together with an iodide-containing variant: La3-xNb1+xS2O5I2x (0La2S2] alternating regularly with perovskite-type oxide slabs [LnMO5] or [La1-xNb1+xO5I2x]. In the oxide slabs, the trivalent and pentavalent cations are disordered on the long-length scale probed by diffraction methods, but bond length considerations suggest that they must be ordered at least on the length scale of the unit cell. The [LnMO5] block of the iodide-free compounds derive from the ideal [Ti2O5] blocks found in Ln2Ti2S2O5 (Ln=Nd-Er; Y) by the formal substitution of two Ti4+ ions with one Ln3+ and one M5+ion. The unusual partial insertion of iodide in the perovskite voids of the [LaNbO5] block in La3NbS2O5 was found to be coupled to a La/Nb substitution, maintaining the charge balance within the [La1-xNb1+xO5I2x]2- block. The Nb5+ ions were found to be too resistant to reduction to undergo the intercalation of alkali metals observed in the Ln2Ti2S2O5 series.

Study of high-Tc interface superconductivity in La1.55Sr0.45CuO4/La2CuO4 heterostructures at high magnetic fields and frequencies

NASA Astrophysics Data System (ADS)

Gasparov, V. A.; Audouard, A.; Drigo, L.; He, Xi; Bozovic, I.

2017-10-01

We have synthesized heterostructures that consist of a layer of a cuprate insulator, La2CuO4, and a layer of a nonsuperconducting cuprate metal, La1.55Sr0.45CuO4. Such bilayers show high-Tc interface superconductivity confined within a single CuO2 plane. Here, we explore the behavior of interface superconductivity at high frequencies (up to 50 MHz) under high magnetic fields (up to 56 T). We find that interface superconductivity persists up to very high perpendicular fields (exceeding 40 T). The critical magnetic field Hm(T) shows an upward divergence with decreasing temperature suggestive of vortex-lattice melting, similar to what is observed in bulk superconducting cuprates.

Metallic Borides, La 2 Re 3 B 7 and La 3 Re 2 B 5 , Featuring Extensive Boron–Boron Bonding

DOE PAGES

Bugaris, Daniel E.; Malliakas, Christos D.; Chung, Duck Young; ...

2016-01-26

We synthesized La 2Re 3B 7 and La 3Re 2B 5 in single-crystalline form from a molten La/Ni eutectic at 1000°C, in the first example of the flux crystal growth of ternary rare-earth rhenium borides. Both compounds crystallize in their own orthorhombic structure types, with La 2Re 3B 7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La 3Re 2B 5 (space group Pmma) having lattice parameters a = 10.809(2) Å, b = 5.287(1) Å, and c = 5.747(1) Å. Furthermore, the compounds possess three-dimensional framework structures thatmore » are built up from rhenium boride polyhedra and boron-boron bonding. La 3Re 2B 5 features fairly common B 2 dumbbells, whereas La 2Re 3B 7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La 3Re 2B 5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La 2Re 3B 7 is a semimetal, which is observed in the electrical resistivity data as measured on single crystals, with behavior obeying the Bloch-Grüneisen model and a room-temperature resistivity ρ300K of ~ 375 μΩ cm. The electronic band structure calculations also suggest that La 3Re 2B 5 is a regular metal.« less

Metallic Borides, La 2 Re 3 B 7 and La 3 Re 2 B 5 , Featuring Extensive Boron–Boron Bonding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bugaris, Daniel E.; Malliakas, Christos D.; Chung, Duck Young

We synthesized La 2Re 3B 7 and La 3Re 2B 5 in single-crystalline form from a molten La/Ni eutectic at 1000°C, in the first example of the flux crystal growth of ternary rare-earth rhenium borides. Both compounds crystallize in their own orthorhombic structure types, with La 2Re 3B 7 (space group Pcca) having lattice parameters a = 7.657(2) Å, b = 6.755(1) Å, and c = 11.617(2) Å, and La 3Re 2B 5 (space group Pmma) having lattice parameters a = 10.809(2) Å, b = 5.287(1) Å, and c = 5.747(1) Å. Furthermore, the compounds possess three-dimensional framework structures thatmore » are built up from rhenium boride polyhedra and boron-boron bonding. La 3Re 2B 5 features fairly common B 2 dumbbells, whereas La 2Re 3B 7 has unique one-dimensional subunits composed of alternating triangular B3 and trans-B4 zigzag chain fragments. Also observed in La 3Re 2B 5 is an unusual coordination of B by an octahedron of La atoms. Electronic band structure calculations predict that La 2Re 3B 7 is a semimetal, which is observed in the electrical resistivity data as measured on single crystals, with behavior obeying the Bloch-Grüneisen model and a room-temperature resistivity ρ300K of ~ 375 μΩ cm. The electronic band structure calculations also suggest that La 3Re 2B 5 is a regular metal.« less

MicroRNA hsa-miR-29b potentiates etoposide toxicity in HeLa cells via down-regulation of Mcl-1.

PubMed

Kollinerová, S; Dostál, Z; Modrianský, M

2017-04-01

Etoposide is commonly used as a monotherapy or in combination with other drugs for cancer treatments. In order to increase the drug efficacy, ceaseless search for novel combinations of drugs and supporting molecules is under way. MiRNAs are natural candidates for facilitating drug effect in various cell types. We used several systems to evaluate the effect of miR-29 family on etoposide toxicity in HeLa cells. We show that miR-29b significantly increases etoposide toxicity in HeLa cells. Because Mcl-1 protein has been recognized as a miR-29 family target, we evaluated downregulation of Mcl-1 protein splicing variant expression induced by miR-29 precursors and confirmed a key role of Mcl-1 protein in enhancing etoposide toxicity. Despite downregulation of Mcl-1 by all three miR-29 family members, only miR-29b significantly enhanced etoposide toxicity. We hypothesized that this difference may be linked to the change in Mcl-1L/Mcl-1S ratio induced by miR-29b. We hypothesized that the change could be due to miR-29b nuclear shuttling. Using specifically modified miR-29b sequences with enhanced cytosolic and nuclear localization we show that there is a difference, albeit statistically non-significant. In conclusion, we show that miR-29b has the synergistic effect with etoposide treatment in the HeLa cells and that this effect is linked to Mcl-1 protein expression and nuclear shuttling of miR-29b. Copyright © 2017 Elsevier Ltd. All rights reserved.

The First Twenty-Five Years: LaGuardia Community College CUNY. LaGuardia Works.

ERIC Educational Resources Information Center

La Guardia Community Coll., Long Island City, NY.

This document chronicles the 25 year history of La Guardia Community College. Chapter 1, "A Sign of Its Times," describes the beginnings of La Guardia Community College, including the first buildings, departments, faculty, and staff members. At a time before the concepts of multiculturalism and diversity entered the mainstream, about…