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Sample records for vacas prenhes previamente

  1. Diverse eucritic pebbles in the Vaca Muerta mesosiderite

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.; Jerde, E. A.

    1987-06-01

    Seven 5-cm basaltic pebbles from the Vaca Muerta mesosiderite were studied by neutron activation and electron microprobe analysis, and three additional pebbles were studied petrographically. The cumulate pebbles had low REE concentrations and high Eu/Sm ratios, indicating the absence of intercumulus liquid. Siderophile interelement ratios were similar to those found in Vaca Muerta metal except for anomalously low Ir concentrations. The presence of 20 percent impact-melt breccias among the pebbles and 35-40 percent melt breccias among the mesosiderite whole-rocks suggests that the mesosiderites were more extensively impact melted than the howardites. Three alternative models to explain this greater proportion of impact-melted material among the mesosiderites are proposed.

  2. Structural Analysis of the Oligomeric States of Helicobacter pylori VacA Toxin

    PubMed Central

    Chambers, Melissa G.; Pyburn, Tasia M.; González-Rivera, Christian; Collier, Scott E.; Eli, Ilyas; Yip, Calvin K.; Takizawa, Yoshimasa; Lacy, D. Borden; Cover, Timothy L.; Ohi, Melanie D.

    2013-01-01

    Helicobacter pylori is a Gram-negative bacterium that colonizes the human stomach and contributes to peptic ulceration and gastric adenocarcinoma. H. pylori secretes a pore-forming exotoxin known as vacuolating toxin (VacA). VacA contains two distinct domains, designated p33 and p55, and assembles into large “snowflake”-shaped oligomers. Thus far, no structural data are available for the p33 domain, which is essential for membrane channel formation. Using single-particle electron microscopy and the random conical tilt approach, we have determined the three-dimensional structures of six VacA oligomeric conformations at ~15-Å resolution. The p55 domain, composed primarily of ?-helical structures, localizes to the peripheral arms, while the p33 domain consists of two globular densities that localize within the center of the complexes. By fitting the VacA p55 crystal structure into the electron microscopy densities, we have mapped inter-VacA interactions that support oligomerization. In addition, we have examined VacA variants/mutants that differ from wild-type (WT) VacA in toxin activity and/or oligomeric structural features. Oligomers formed by VacA?6–27, a mutant that fails to form membrane channels, lack an organized p33 central core. Mixed oligomers containing both WT and VacA?6–27 subunits also lack an organized core. Oligomers formed by a VacA s2m1 chimera (which lacks cell-vacuolating activity) and VacA?301–328 (which retains vacuolating activity) each contain p33 central cores similar to those of WT oligomers. By providing the most detailed view of the VacA structure to date, these data offer new insights into the toxin's channel-forming component and the intermolecular interactions that underlie oligomeric assembly. PMID:23178866

  3. Vacuolating cytotoxin A (VacA), a key toxin for Helicobacter pylori pathogenesis

    PubMed Central

    Palframan, Samuel L.; Kwok, Terry; Gabriel, Kipros

    2012-01-01

    More than 50% of the world's population is infected with Helicobacter pylori (H. pylori). Chronic infection with this Gram-negative pathogen is associated with the development of peptic ulcers and is linked to an increased risk of gastric cancer. H. pylori secretes many proteinaceous factors that are important for initial colonization and subsequent persistence in the host stomach. One of the major protein toxins secreted by H. pylori is the Vacuolating cytotoxin A (VacA). After secretion from the bacteria via a type V autotransport secretion system, the 88 kDa VacA toxin (comprised of the p33 and p55 subunits) binds to host cells and is internalized, causing severe “vacuolation” characterized by the accumulation of large vesicles that possess hallmarks of both late endosomes and early lysosomes. The development of “vacuoles” has been attributed to the formation of VacA anion-selective channels in membranes. Apart from its vacuolating effects, it has recently become clear that VacA also directly affects mitochondrial function. Earlier studies suggested that the p33 subunit, but not the p55 subunit of VacA, could enter mitochondria to modulate organelle function. This raised the possibility that a mechanism separate from pore formation may be responsible for the effects of VacA on mitochondria, as crystallography studies and structural modeling predict that both subunits are required for a physiologically stable pore. It has also been suggested that the mitochondrial effects observed are due to indirect effects on pro-apoptotic proteins and direct effects on mitochondrial morphology-related processes. Other studies have shown that both the p55 and p33 subunits can indeed be efficiently imported into mammalian-derived mitochondria raising the possibility that they could re-assemble to form a pore. Our review summarizes and consolidates the recent advances in VacA toxin research, with focus on the outstanding controversies in the field and the key remaining questions that need to be addressed. PMID:22919683

  4. What exists beyond cagA and vacA? Helicobacter pylori genes in gastric diseases

    PubMed Central

    da Costa, Débora Menezes; Pereira, Eliane dos Santos; Rabenhorst, Silvia Helena Barem

    2015-01-01

    Helicobacter pylori (H. pylori) infection is present in more than half the world’s population and has been associated with several gastric disorders, such as gastritis, peptic ulceration, and gastric adenocarcinoma. The clinical outcome of this infection depends on host and bacterial factors where H. pylori virulence genes seem to play a relevant role. Studies of cagA and vacA genes established that they were determining factors in gastric pathogenesis. However, there are gastric cancer cases that are cagA-negative. Several other virulence genes have been searched for, but these genes remain less well known that cagA and vacA. Thus, this review aimed to establish which genes have been suggested as potentially relevant virulence factors for H. pylori-associated gastrointestinal diseases. We focused on the cag-pathogenicity island, genes with adherence and motility functions, and iceA based on the relevance shown in several studies in the literature. PMID:26457016

  5. Characterization of Helicobacter pylori?VacA-containing vacuoles (VCVs), VacA intracellular trafficking and interference with calcium signalling in T lymphocytes.

    PubMed

    Kern, Beate; Jain, Utkarsh; Utsch, Ciara; Otto, Andreas; Busch, Benjamin; Jiménez-Soto, Luisa; Becher, Dörte; Haas, Rainer

    2015-12-01

    The human pathogen Helicobacter pylori colonizes half of the global population. Residing at the stomach epithelium, it contributes to the development of diseases such as gastritis, duodenal and gastric ulcers, and gastric cancer. A major factor is the secreted vacuolating toxin VacA, which forms anion-selective channels in the endosome membrane that cause the compartment to swell, but the composition and purpose of the resulting VacA-containing vacuoles (VCVs) are still unknown. VacA exerts influence on the host immune response in various ways, including inhibition of T-cell activation and proliferation and suppression of the host immune response. In this study, for the first time the composition of VCVs from T cells was comprehensively analysed to investigate VCV function. VCVs were successfully isolated via immunomagnetic separation, and the purified vacuoles were analysed by mass spectrometry. We detected a set of 122 VCV-specific proteins implicated among others in immune response, cell death and cellular signalling processes, all of which VacA is known to influence. One of the individual proteins studied further was stromal interaction molecule (STIM1), a calcium sensor residing in the endoplasmic reticulum (ER) that is important in store-operated calcium entry. Live cell imaging microscopy data demonstrated colocalization of VacA with STIM1 in the ER and indicated that VacA may interfere with the movement of STIM1 towards the plasma membrane-localized calcium release activated calcium channel protein ORAI1 in response to Ca(2+) store depletion. Furthermore, VacA inhibited the increase of cytosolic-free Ca(2+) in the Jurkat E6-1 T-cell line and human CD4(+) T cells. The presence of VacA in the ER and its trafficking to the Golgi apparatus was confirmed in HeLa cells, identifying these two cellular compartments as novel VacA target structures. PMID:26078003

  6. CagA and VacA genotypes in peptic ulcer disease and non-ulcer dyspepsia: a case-control study

    PubMed Central

    FakhreYaseri, Hashem; Shakaraby, Mehdi; Bradaran, Hamid Reza; Soltani Arabshahi, Seyed Kamran; Fakhre Yaseri, Ali Mohammad

    2014-01-01

    Background: The cag pathogenicity island includes a number of genes, including cytotoxin-associated protein A (cagA) and vacuolating cytotoxin (vacA) genotypes, which are associated with bacterial virulence. Although the role of cagA and vacA in the virulence of Helicobacter pylori (H. pylori) is well-established in epidemiological studies, the relationship between the cagA and vacA genotypes in Iran has yet to be fully elucidated. This study compared the association between cagA and vacA genotypes between peptic ulcer disease (PUD) patients and non-ulcer dyspeptic (NUD) patients. Methods: This case control study was done on 130 patients with positive H. pylori in histological and Giemsa reports. The case group comprised 65 PUD patients, and the control group included 65 NUD patients. The presence of the cagA and vacA genotypes was determined using polymerase chain reaction (PCR) on biopsy samples, taken via endoscopy. Results: Both cagA and vacA genotypes were positive in 51.5% (17) of the PUD group and 20% (6) of the NUD group (p= 0.009), and both cagA and vacA genotypes were negative in 48.5% (16) and 80% (24) of the case and control groups, respectively (p= 0.03). CagA-positive H. pylori was detected in 41.5% (27) and 24.6% (16) of the case and control groups, respectively (p= 0.001), and vacA-positive H. pylori was found in 60% (39) and 46% (30) of the case and control groups, respectively. Conclusion: Both cagA and vacA genotypes were more prevalent in the PUD patients than in their NUD counterparts among our Iranian samples. It is seems that the determination of these two genotypes in PUD patients is a good screening tool for patient selection for endoscopy and treatment. PMID:25664305

  7. New fossil record of a Jurassic pterosaur from Neuquen Basin, Vaca Muerta Formation, Argentina

    NASA Astrophysics Data System (ADS)

    Codorniú, Laura; Garrido, Alberto

    2013-12-01

    Discoveries of Jurassic pterosaurs in the Southern Hemisphere are extremely unusual. In Argentina, pterosaurs from the Upper Jurassic (Tithonian) have only been found in the Northwest of Patagonia (Neuquén Basin). These come from marine deposits and three specimens have been discovered up to the present. In this paper, we report a new finding from the Neuquén Basin. This material is identified as a tibiotarsus, which probably belonged to an osteologically adult individual and represents a new species of a pterodactyloid pterosaur of medium size. This discovery provides new evidence that at least two different species of pterodactyloid pterosaurs may have coexisted in Los Catutos Member, Vaca Muerta Formation, from the shallow marine deposits of the Neuquén Basin.

  8. [Molecular detection of Helicobacter pylori vacA and cagA genes in gastric tissue specimens of patients with peptic ulcer disease and non-ulcer dyspepsia].

    PubMed

    Karaman, Meral; Abac?o?lu, Hakan; Topalak, Omer S; Sim?ek, Ilkay

    2011-01-01

    Helicobacter pylori can colonize the gastric mucosa and is considered as a risk factor for chronic active gastritis, peptic ulcer, gastric adenocarcinoma and primary gastric lymphoma. Among its various virulence factors, vacuolating cytotoxin encoded by vacA and cytotoxin-associated toxin encoded by cagA gene play an important role. The aims of this study were the detection of H.pylori vacA s and m genotypes, investigation of the association between vacA genotypes and cagA gene presence, and evaluation of the correlation between those factors and the clinical diagnosis. Gastric tissue specimens of patients who were clinically diagnosed as peptic ulcer disease (PUD) and non-ulcer dyspepsia (NUD) were included in the study. A total of 29 patients (age range: 18-74 years, mean age: 47.8 ± 13.6 years; 19 were female) without any familial relationship were evaluated. Thirteen (44.8%) of the patients were diagnosed clinically as PUD, while 16 (55.2%) as NUD. All of the patients' gastric tissue samples obtained by endoscopy were urease positive. H.pylori DNA was extracted from the tissue specimens by proteinase-K, phenol-chloroform-isoamyl alcohol method and vacA s, m1, m2 and cagA regions were identified by polymerase chain reaction (PCR) using four different primer sets. In addition, DNA sequencing was performed for the protected 785 base-pairs region of vacA m gene in all of the samples, and the sequences were aligned with Gene-Bank sequences, creating a phylogenetic tree. The distribution of vacA genotypes between 29 H.pylori positive patients were found as; s1m1 (n= 16), s1m2 (n= 6) and s2m2 (n= 7), while 19 patients yielded positive results for cagA gene. CagA positivity was detected in all of the 16 patients harboring s1m1 genotype, and 13 of those were the patients diagnosed as PUD (p= 0.008). Genotyping data achieved by phylogenetic analysis of the vacA m region were compatible with m genotypes identified by PCR. In conclusion, we detected a significant relationship between PUD and vacA s1m1 and cagA positivity. It was also determined that PCR would be a reliable, simpler and cheaper alternative to nucleotide sequencing for the identification of H.pylori vacA m genotypes. PMID:21341154

  9. Association of IL1B -511C/-31T haplotype and Helicobacter pylori vacA genotypes with gastric ulcer and chronic gastritis

    PubMed Central

    2010-01-01

    Background The association between proinflammatory cytokine gene polymorphisms and gastric diseases related to Helicobacter pylori varies by population and geographic area. Our objective was to determine if the IL-1B -511 T>C and -31 C>T polymorphisms and H. pylori vacA genotypes are associated with risk of chronic gastritis and gastric ulcer in a Mexican population. Methods We conducted endoscopic studies in 128 patients with symptoms of dyspepsia. We took two biopsies from the body, antrum, or ulcer edge from each patient, and classified our histopathological findings according to the Sydney System. H. pylori infection and vacA genotyping were accomplished via PCR from total DNA of the gastric biopsies. We confirmed the presence of anti-H. pylori serum IgG and IgM in 102 control subjects. In both case subjects and control subjects, the IL-1B -511 T>C polymorphism was genotyped by PCR-RFLPs and the IL-1B -31 C>T polymorphism was genotyped by pyrosequencing. Results Sixty-two point seven (62.7%) of the 102 control subjects were H. pylori-seropositive. Among the case subjects, 100 were diagnosed with chronic gastritis and 28 with gastric ulcer. We found that 77% of the patients with chronic gastritis and 85.7% of the patients with gastric ulcer were H. pylori-positive. The predominant H. pylori genotype was vacA s1m1 (58.4%) and the most frequent subtype was vacA s1. The -511 TC, (rs16944 -511 T>C) genotype and the -511C allele were associated with chronic gastritis (OR = 3.1, 95% CI = 1.4-6.8 and OR = 3.0, 95% CI = 1.4-6.0, respectively). The subjects carrying -31T (rs1143627 -31 C>T) were found to be at a higher risk of having chronic gastritis (OR = 2.8, 95% CI = 1.3-5.8). The IL-1B -511C/-31T haplotype was associated with chronic gastritis (OR = 2.1, 95% CI = 1.2-3.8) but not with gastric ulcer. Conclusions The H. pylori vacA genotypes identified herein were similar to those reported for other regions of Mexico. The vacA s1m1 genotype was not associated with gastric ulcer. In the southern Mexican population, the IL-1B -511C and -31T alleles and the -511C/-31T and -511T/-31T haplotypes are associated with increased risk of chronic gastritis and gastric ulcer. PMID:20979650

  10. Relationship between Tobacco, cagA and vacA i1 Virulence Factors and Bacterial Load in Patients Infected by Helicobacter pylori

    PubMed Central

    Aguirre, Estefanía; Aragones, Nuria; Saez, Jesús; Galiana, Antonio; Sola-Vera, Javier; Ruiz-García, Montserrat; Paz-Zulueta, María; Sarabia-Lavín, Raquel; Brotons, Alicia; López-Girona, Elena; Pérez, Estefanía; Sillero, Carlos

    2015-01-01

    Background and Aim Several biological and epidemiological studies support a relationship between smoking and Helicobacter pylori (H. pylori) to increase the risk of pathology. However, there have been few studies on the potential synergistic association between specific cagA and vacA virulence factors and smoking in patients infected by Helicobacter pylori. We studied the relationship between smoking and cagA, vacA i1 virulence factors and bacterial load in H. pylori infected patients. Methods Biopsies of the gastric corpus and antrum from 155 consecutive patients in whom there was clinical suspicion of infection by H. pylori were processed. In 106 patients H. pylori infection was detected. Molecular methods were used to quantify the number of microorganisms and presence of cagA and vacA i1 genes. A standardized questionnaire was used to obtain patients’ clinical data and lifestyle variables, including tobacco and alcohol consumption. Adjusted Odds Ratios (ORadjusted) were estimated by unconditional logistic regression. Results cagA was significantly associated with active-smoking at endoscope: ORadjusted 4.52. Evidence of association was found for vacA i1 (ORadjusted 3.15). Bacterial load was higher in active-smokers, although these differences did not yield statistical significance (median of 262.2 versus 79.4 copies of H. pylori per cell). Conclusions The association between smoking and a higher risk of being infected by a virulent bacterial population and with higher bacterial load, support a complex interaction between H. pylori infection and environmental factors. PMID:25794002

  11. Fish faunas from the Late Jurassic (Tithonian) Vaca Muerta Formation of Argentina: One of the most important Jurassic marine ichthyofaunas of Gondwana

    NASA Astrophysics Data System (ADS)

    Gouiric-Cavalli, Soledad; Cione, Alberto Luis

    2015-11-01

    The marine deposits of the Vaca Muerta Formation (Tithonian-Berriasian) houses one of the most diverse Late Jurassic ichthyofaunas of Gondwana. However, most of the specimens remain undescribed. Jurassic fishes have been recovered from several localities at Neuquén Province (i.e., Picún Leufú, Plaza Huincul, Cerro Lotena, Portada Las Lajas, Los Catutos, and Arroyo Covunco) but also from Mendoza Province (i.e., La Valenciana, Los Molles, and Arroyo del Cajón Grande). Presently, the fish fauna of Los Catutos, near Zapala city (Neuquén Province), has yielded the highest number of specimens, which are taxonomically and morphologically diverse. At Los Catutos locality, the Vaca Muerta Formation is represented by the Los Catutos Member, which is considered the only lithographic limestones known in the Southern Hemisphere. Here, we review the Tithonian fish faunas from the Vaca Muerta Formation. During Late Jurassic times, the actual Argentinian territory could have been a morphological diversification center, at least for some actinopterygian groups. The apparently lower species diversity recorded in marine Jurassic ichthyofaunas of Argentina (and some Gondwanan countries) in comparison with Chilean and European fish faunas could be related to the fish paleontological research history in Gondwana and the low number of detailed studies of most of specimens recorded.

  12. Helicobacter pylori bab Paralog Distribution and Association with cagA, vacA, and homA/B Genotypes in American and South Korean Clinical Isolates

    PubMed Central

    Kang, Jieun; Kim, Jinmoon; Jang, Sungil; Cha, Ho Jin; Lee, Wan Jin; Kim, June; Romero-Gallo, Judith; Peek, Richard M.; Merrell, D. Scott; Cha, Jeong-Heon

    2015-01-01

    Helicobacter pylori genetic variation is a crucial component of colonization and persistence within the inhospitable niche of the gastric mucosa. As such, numerous H. pylori genes have been shown to vary in terms of presence and genomic location within this pathogen. Among the variable factors, the Bab family of outer membrane proteins (OMPs) has been shown to differ within subsets of strains. To better understand genetic variation among the bab genes and to determine whether this variation differed among isolates obtained from different geographic locations, we characterized the distribution of the Bab family members in 80 American H. pylori clinical isolates (AH) and 80 South Korean H. pylori clinical isolates (KH). Overall, we identified 23 different bab genotypes (19 in AH and 11 in KH), but only 5 occurred in greater than 5 isolates. Regardless of strain origin, a strain in which locus A and locus B were both occupied by a bab gene was the most common (85%); locus C was only occupied in those isolates that carried bab paralog at locus A and B. While the babA/babB/- genotype predominated in the KH (78.8%), no single genotype could account for greater than 40% in the AH collection. In addition to basic genotyping, we also identified associations between bab genotype and well known virulence factors cagA and vacA. Specifically, significant associations between babA at locus A and the cagA EPIYA-ABD motif (P<0.0001) and the vacA s1/i1/m1 allele (P<0.0001) were identified. Log-linear modeling further revealed a three-way association between bab carried at locus A, vacA, and number of OMPs from the HOM family (P<0.002). En masse this study provides a detailed characterization of the bab genotypes from two distinct populations. Our analysis suggests greater variability in the AH, perhaps due to adaptation to a more diverse host population. Furthermore, when considering the presence or absence of both the bab and homA/B paralogs at their given loci and the vacA genotype, an association was observed. Our results highlight the multifactorial nature of H. pylori mediated disease and the importance of considering how the specific combinations of H. pylori virulence genes and their multiple interactions with the host will collectively impact disease progression. PMID:26317221

  13. Helicobacter pylori Genotyping from American Indigenous Groups Shows Novel Amerindian vacA and cagA Alleles and Asian, African and European Admixture

    PubMed Central

    Camorlinga-Ponce, Margarita; Perez-Perez, Guillermo; Gonzalez-Valencia, Gerardo; Mendoza, Irma; Peñaloza-Espinosa, Rosenda; Ramos, Irma; Kersulyte, Dangeruta; Reyes-Leon, Adriana; Romo, Carolina; Granados, Julio; Muñoz, Leopoldo; Berg, Douglas E.; Torres, Javier

    2011-01-01

    It is valuable to extend genotyping studies of Helicobacter pylori to strains from indigenous communities across the world to better define adaption, evolution, and associated diseases. We aimed to genetically characterize both human individuals and their infecting H. pylori from indigenous communities of Mexico, and to compare them with those from other human groups. We studied individuals from three indigenous groups, Tarahumaras from the North, Huichols from the West and Nahuas from the center of Mexico. Volunteers were sampled at their community site, DNA was isolated from white blood cells and mtDNA, Y-chromosome, and STR alleles were studied. H. pylori was cultured from gastric juice, and DNA extracted for genotyping of virulence and housekeeping genes. We found Amerindian mtDNA haplogroups (A, B, C, and D), Y-chromosome DYS19T, and Amerindian STRs alleles frequent in the three groups, confirming Amerindian ancestry in these Mexican groups. Concerning H.pylori cagA phylogenetic analyses, although most isolates were of the Western type, a new Amerindian cluster neither Western nor Asian, was formed by some indigenous Mexican, Colombian, Peruvian and Venezuelan isolates. Similarly, vacA phylogenetic analyses showed the existence of a novel Amerindian type in isolates from Alaska, Mexico and Colombia. With hspA strains from Mexico and other American groups clustered within the three major groups, Asian, African or European. Genotyping of housekeeping genes confirmed that Mexican strains formed a novel Asian-related Amerindian group together with strains from remote Amazon Aborigines. This study shows that Mexican indigenous people with Amerindian markers are colonized with H. pylori showing admixture of Asian, European and African strains in genes known to interact with the gastric mucosa. We present evidence of novel Amerindian cagA and vacA alleles in indigenous groups of North and South America. PMID:22073291

  14. CagA phosphorylation EPIYA-C motifs and the vacA i genotype in Helicobacter pylori strains of asymptomatic children from a high-risk gastric cancer area in northeastern Brazil

    PubMed Central

    Braga, Lucia Libanez Bessa Campelo; de Oliveira, Maria Aparecida Alves; Gonçalves, Maria Helane Rocha Batista; Chaves, Fernando Kennedy; Benigno, Tiago Gomes da Silva; Gomes, Adriana Dias; Silva, Cícero Igor Simões Moura; Anacleto, Charles; Batista, Sérgio de Assis; Queiroz, Dulciene Maria Magalhães

    2014-01-01

    Helicobacter pylori infection is one of the most common infections worldwide and is associated with gastric diseases. Virulence factors such as VacA and CagA have been shown to increase the risk of these diseases. Studies have suggested a causal role of CagA EPIYA-C in gastric carcinogenesis and this factor has been shown to be geographically diverse. We investigated the number of CagA EPIYA motifs and the vacA i genotypes in H. pylori strains from asymptomatic children. We included samples from 40 infected children (18 females and 22 males), extracted DNA directly from the gastric mucus/juice (obtained using the string procedure) and analysed the DNA using polymerase chain reaction and DNA sequencing. The vacA i1 genotype was present in 30 (75%) samples, the i2 allele was present in nine (22.5%) samples and both alleles were present in one (2.5%) sample. The cagA-positive samples showed distinct patterns in the 3’ variable region of cagA and 18 of the 30 (60%) strains contained 1 EPIYA-C motif, whereas 12 (40%) strains contained two EPIYA-C motifs. We confirmed that the studied population was colonised early by the most virulent H. pylori strains, as demonstrated by the high frequency of the vacA i1 allele and the high number of EPIYA-C motifs. Therefore, asymptomatic children from an urban community in Fortaleza in northeastern Brazil are frequently colonised with the most virulent H. pylori strains. PMID:25494468

  15. Multilayer adsorption of Cu(II) and Cd(II) over Brazilian Orchid Tree (Pata-de-vaca) and its adsorptive properties

    NASA Astrophysics Data System (ADS)

    Jorgetto, Alexandre de O.; da Silva, Adrielli C. P.; Wondracek, Marcos H. P.; Silva, Rafael I. V.; Velini, Edivaldo D.; Saeki, Margarida J.; Pedrosa, Valber A.; Castro, Gustavo R.

    2015-08-01

    Through very simple and inexpensive processes, pata-de-vaca leaves were turned into a powder and applied as an adsorbent for the uptake of Cu(II) and Cd(II) from water. The material was characterized through SEM, EDX, FTIR and surface area measurement. The material had its point of zero charge determined (5.24), and its adsorption capacity was evaluated as a function of time, pH and metal concentration. The material presented fast adsorption kinetics, reaching adsorption equilibrium in less than 5 min and it had a good correlation with the pseudo-second order kinetic model. Optimum pH for the adsorption of Cu(II) and Cd(II) were found to be in the range from 4 to 5, approximately. In the experiment as a function of the analyte concentration, analogously to gas adsorption, the material presented a type II isotherm, indicating the formation of multilayers for both species. Such behavior was explained with basis in the alternation between cations and anions over the material's surface, and the maximum adsorption capacity, considering the formation of the multilayers were found to be 0.238 mmol L-1 for Cu(II) and 0.113 mmol L-1 for Cd(II).

  16. Nuevas Perspectivas en la Efficiencia del Uso Nirogeno en Vaca Lecheras

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy cows utilize feed crude protein (CP) with greater efficiency than other ruminants, but still excrete about 2 to 3 times more nitrogen (N) in manure than they secrete in milk. This increases milk production costs plus environmental N pollution. Optimizing microbial protein formation in the rume...

  17. ESTRATEGIAS PARA HACER EL MEJOR USO DE LA PROTEINA EN RACIONES PARA VACAS LECHERAS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy cows utilize feed CP with greater efficiency than other ruminants, but still excrete about 2 to 3 times more N in manure than they secrete in milk. This increases milk production costs plus environmental N pollution. Optimizing microbial protein formation in the rumen is the most effective way...

  18. MEJORANDO LA UTILIZACION DE LA PROTEINA EN LA VACA LECHERA EN LACTANCIA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dairy cows utilize feed CP with greater efficiency than other ruminants, but still excrete about 2 to 3 times more N in manure than they secrete in milk. This increases milk production costs plus environmental N pollution. Maximizing microbial protein formation in the rumen is the most effective way...

  19. The Low-Level Atmospheric Circulation near Tongoy Bay–Point Lengua de Vaca (Chilean Coast, 30°S)

    E-print Network

    Rahn, David A.; Garreaud, René D.; Rutllant, José A.

    2011-11-01

    ) the most comprehensive dataset is available for this period. Diurnal variation of temperature and wind over the 8-day period is shown for 4 key locations: TCR, LdV, TGY, and QSC (Fig. 6). LdV exhibits a considerable diurnal cycle in both wind components... observations (along the coast, on buoys, and on an island), radiosondes, radar-derived sea surface currents, and ocean currents and temperature from a pair of coastal moorings. The in situ observations have been complemented with airborne meteorological...

  20. Field evaluation of three plant-based insect repellents against malaria vectors in Vaca Diez Province, the Bolivian Amazon.

    PubMed

    Moore, Sarah J; Lenglet, Annick; Hill, Nigel

    2002-06-01

    The efficacy of repellents against Anopheles darlingi, the main malaria vector in Bolivia, was evaluated. This mosquito has a peak in biting activity early in the evening. Three natural repellents (1 eucalyptus based, 1 neem based, and 1 containing several repellent essential oils) were tested in comparison with 15% deet in human landing catches in Bolivia. The eucalyptus-based repellent containing 30% p-menthane-diol applied at a dose similar to those used in practice gave 96.89% protection for 4 h. Deet gave 84.81% protection. The other 2 products did not provide significant protection from mosquito bites. PMID:12083351

  1. Newly Discovered Paleocene and Eocene Rocks near Fairfield, California, and Correlation with Rocks in Vaca Valley and the So-Called Martinez Formation or Stage

    USGS Publications Warehouse

    Brabb, Earl E.; Ristau, Donn; Bukry, David; McDougall, Kristin; Almgren, Alvin A.; Saul, LouElla; Sanfilippo, Annika

    2008-01-01

    Discovery of a 3-foot thick sandstone bed with abundant Turritellid gastropods of late Paleocene age about 4 miles northeast of Fairfield and on the southwest flank of Cement Hill, Solano County provides an opportunity to reevaluate the relationships of lower Tertiary formations in this part of California. Cement Hill is named for travertine deposits in and on top of sandstone of Late Cretaceous age. In this report, the current study area where the Paleocene fossils were recently discovered is referred to as lower Cement Hill and is located in section 7 of the U.S. Geological Survey Fairfield North 7.5-minute quadrangle, Township 5 North, Range 1 West. Lower Cement Hill is about 23 miles north of the so-called Martinez 'formation' or stage area (Weaver and others, 1941) of late Paleocene age near Martinez. The Martinez 'formation' and stage have played a significant role in the development of early Tertiary stratigraphy in this part of California. The discovery of correlative rocks at Cement Hill was unsuspected and may be helpful in defining the extent of this so-called formation or stage. Coccolith identification and correlations are by David Bukry, foraminifer identifications and correlations by Alvin Almgren and Kristin McDougall, gastropod identification and correlation by LouElla Saul, and Radiolaria identifications and correlations are by Annika Sanfilippo.

  2. Detección de compuestos inductores de aborto en acículas de enebro (Juniperus communis) y suero de vacas abortadas en los montes de la Rioja

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over recent years, there have been observed in several cattle farms within the region of the Sierra de Cameros (La Rioja) mountains, reproductive alterations consisting of pre-mature births and birth of dead calves or calves of reduced viability. After laboratory examination of several cases with ne...

  3. Molecular Basis of Pathogenicity in Helicobacter pylori Clinical Isolates ?

    PubMed Central

    Ramis, Ivy Bastos; Fonseca, Tesiê Leopoldo; Moraes, Ernani Pinho de; Fernandes, Márcia Silveira; Mendoza-Sassi, Raul; Rodrigues, Obirajara; Juliano, Carlos Renan Varela; Scaini, Carlos James; Almeida da Silva, Pedro Eduardo

    2010-01-01

    This study identified pathogenicity genes in 40 Helicobacter pylori clinical isolates. The cagA, vacA, and iceA genes were detected in 65%, 97.5%, and 97.5% of the isolates, respectively. The cagA, iceA1, and vacAs1a/m1 genes were related to erosive gastritis, whereas the vacAs2/m2 and iceA2 genes were associated with enanthematous gastritis. PMID:20686086

  4. 75 FR 46932 - Notice of Receipt of Requests to Voluntarily Cancel Certain Pesticide Registrations

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-04

    ...South Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries...South Bldg.), 2777 S. Crystal Dr., Arlington, VA...CA900010 Volck Supreme Mineral Oil - Spray includes paraffin...CA910030 Volck Supreme Mineral Oil - Spray includes...

  5. Development of a methodology for evaluating investments in infrastructure for the sustainable exploitation of shale energy in Argentina

    E-print Network

    Agosta, Bruno R

    2015-01-01

    In 2011, a new word entered into the popular vocabulary of Argentina: Vaca Muerta (VM, literally: Dead Cow); almost like a discovery, it was announced that Argentina had large hydrocarbon resources that were trapped in ...

  6. Reciprocal impact of host factors and Helicobacter pylori genotypes on gastric diseases

    PubMed Central

    Honarmand-Jahromy, Sahar; Siavoshi, Farideh; Malekzadeh, Reza; Nejad Sattari, Taher; Latifi-Navid, Saeid

    2015-01-01

    AIM: To assess the impact of Helicobacter pylori (H. pylori) genotypes and patient age and sex on the development of gastric diseases. METHODS: H. pylori-infected patients (n = 233) referred to the endoscopy unit at Tehran University of Medical Sciences (Tehran, Iran) were diagnosed with chronic gastritis (CG), gastric ulcer (GU), or duodenal ulcer (DU). Brucella blood agar was used for biopsy cultures and H. pylori isolation under microaerobic conditions. H. pylori isolates were confirmed with biochemical tests and through amplification of the 16S rRNA gene. DNA was extracted from fresh cultures of the H. pylori isolates and used for amplification of vacA alleles and the cagA gene. Statistical analysis was performed to determine the association between H. pylori genotypes, age (< 40 years vs > 40 years) and sex of the patient, and gastric diseases. RESULTS: CG was the most prevalent gastric disease (113/233; 48.5%), compared to GU (64/233; 27.5%) and DU (56/233; 24%). More patients were male, and gastric diseases were more frequent in patients > 40 years (P < 0.05). The percentage of CG and GU patients that were male and female did not show a significant difference; however DU was more common in males (P < 0.05). Interestingly, a diagnosis of CG in patients > 40 years was more common in females (18.5%) than males (11.6%) (P = 0.05), whereas a diagnosis of GU or DU in patients > 40 years was more frequent in males (14.6% vs 10.7% and 12.4% vs 4.3%, respectively). Overall, genotyping of the H. pylori isolates revealed that the vacA s1 (82%), vacA m2 (70%), and cagA+ (72.5%) alleles were more frequent than vacA s2 (18%), vacA m1 (29.2%), and cagA- (all P < 0.05). The vacA s1m2cagA+ genotype was the most prevalent within the three disease groups. vacA s1m2 frequency was 56.2% with a similar occurrence in all diagnoses, while vacA s1m1 appeared more often in DU patients (33.9%). A genotype of vacA s2m2 occurred in 15% of isolates and was more common in CG patients (21.2%); vacA s2m1 was the least common genotype (3%). The vacA s1 allele was found to be a risk factor for DU, vacA s2 for CG, and vacA s1 and vacA s2 for GU (all P < 0.05). The vacA s2m2 genotype was associated with the development of CG and GU compared to DU (P < 0.05). No correlation was found between vacA m or cagA and gastric diseases. CONCLUSION: The outcome of H. pylori infection is the result of interaction between bacterial genotypes and the age and sex of infected individuals. PMID:26309357

  7. The Prevalence of Helicobacter pylori Virulence Factors in Bhutan, Vietnam, and Myanmar Is Related to Gastric Cancer Incidence

    PubMed Central

    Trang, Tran Thi Huyen; Shiota, Seiji; Matsuda, Miyuki; Binh, Tran Thanh; Suzuki, Rumiko; Vilaichone, Ratha-korn; Mahachai, Varocha; Tshering, Lotay; Dung, Ho D. Q.; Uchida, Tomohisa; Matsunari, Osamu; Myint, Thein; Khien, Vu Van; Yamaoka, Yoshio

    2015-01-01

    Gastric cancer is a significant health problem in Asia. Although the prevalence of Helicobacter pylori infection is similar in Bhutan, Vietnam, and Myanmar, the incidence of gastric cancer is highest in Bhutan, followed by Vietnam and Myanmar. We hypothesized that H. pylori virulence factors contribute to the differences. The status of cagA, vacA, jhp0562, and ?-(1,3)galT(jhp0563) was examined in 371 H. pylori-infected patients from Bhutan, Vietnam, and Myanmar. Each virulence factor could not explain the difference of the incidence of gastric cancer. However, the prevalence of quadruple-positive for cagA, vacA s1, vacA m1, and jhp0562-positive/?-(1,3)galT-negative was significantly higher in Bhutan than in Vietnam and Myanmar and correlated with gastric cancer incidence. Moreover, gastritis-staging scores measured by histology of gastric mucosa were significantly higher in quadruple-positive strains. We suggest that the cagA, vacA s1, vacA m1, and jhp0562-positive/?-(1,3)galT-negative genotype may play a role in the development of gastric cancer. PMID:26090448

  8. A Herpesvirus Specific Motif of Epstein-Barr Virus DNA Polymerase Is Required for the Efficient Lytic Genome Synthesis

    PubMed Central

    Narita, Yohei; Sugimoto, Atsuko; Kawashima, Daisuke; Watanabe, Takahiro; Kanda, Teru; Kimura, Hiroshi; Tsurumi, Tatsuya; Murata, Takayuki

    2015-01-01

    Epstein-Barr virus (EBV) is associated with several malignancies, including Burkitt lymphoma and nasopharyngeal carcinoma. To overcome such disorders, understanding the molecular mechanisms of the EBV replication is important. The EBV DNA polymerase (Pol) is one of the essential factors for viral lytic DNA replication. Although it is well known that its C-terminal half, possessing DNA polymerase and 3’-5’ exonuclease activity, is highly conserved among Family B Pols, the NH2-terminal half has yet to be characterized in detail. In this study, we show that a stretch of hydrophobic amino acids within the pre-NH2-terminal domain of EBV Pol plays important role. In addition, we could identify the most essential residue for replication in the motif. These findings will shed light on molecular mechanisms of viral DNA synthesis and will help to develop new herpesviruses treatments. PMID:26123572

  9. GUIA DE FORMULARIOS PARA LA ACREDITACIN DE CARRERAS

    E-print Network

    . Infraestructura, apoyo técnico y recursos para la enseñanza 10. Vinculación con el medio. Los formularios de esta declarados y criterios previamente definidos. Para poder emitir juicios respecto de ambos aspectos, es

  10. 29 June 2010 Aristotle put together a list of birds (n =170)

    E-print Network

    Butler, Christopher J.

    over eight volumes, including 39 never before illustrated John James Audubon (1785-1851) Published birds passing." - Christopher Columbus De Vaca (1528), Castenada (1541-1542) noted birds John White (1585) painted watercolors The Ornithology of Francis Willughby (1678) by Willughby and John Ray

  11. A synoptic climatology of the near-surface wind along the west coast of South America

    E-print Network

    Rahn, David A.; Garreaud, René D.

    2013-05-20

    Vaca (30.0°S), and Punta Lavapie (36.4°S). Previous work has identified local maxima at these points but these are embedded in a broader low-level jet that exhibits a marked seasonal cycle of strong wind days due to the migration of the anticyclone...

  12. 78 FR 67133 - Combined Notice of Filings #1

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-08

    ... Commission received the following land acquisition reports: Docket Numbers: LA13-3-000. Applicants: CalPeak Power LLC, CalPeak Power--Border LLC, CalPeak Power--Enterprise LLC, CalPeak Power--Panoche LLC, CalPeak Power--Vaca Dixon LLC Starwood Power-Midway LLC. Description: Quarterly Land Acquisition Report of...

  13. 78 FR 43193 - Combined Notice of Filings #1

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-19

    ... following electric corporate filings: Docket Numbers: EC13-125-000. Applicants: CalPeak Power LLC, CalPeak Power--Border LLC, CalPeak Power--Panoche LLC, CalPeak Power--Vaca Dixon LLC, CalPeak Power-- Enterprise LLC. Description: Application of CalPeak Power, LLC, et al. for Authorization under Section 203 of...

  14. Hurricane Rita Preliminary Water Levels Report *For the purpose of timely release, data contained within this report have undergone a "limited" NOS Quality

    E-print Network

    Hurricane Rita Preliminary Water Levels Report *For the purpose of timely release, data contained water levels during the landfall of Hurricane RITA from Vaca Key, FL to Port Isabel, TX. Station of Storm Tide Anomoly is discounted. Hurricane RITA made landfall on 24 September 2005 at 2:38 CDT (7

  15. EXPLORATION OF UNDER-ICE REGIONS WITH OCEAN PROFILING AGENTS (EUROPA)

    E-print Network

    Virginia Tech

    EXPLORATION OF UNDER-ICE REGIONS WITH OCEAN PROFILING AGENTS (EUROPA) D. W. Allen, M. Jones, L. Mc. VaCAS-2013-01 Copyright c 2013 #12;#12;Summary Europa is an incredibly enticing target science decadal survey [1] have affirmed the pre- eminence of Europa as a destination for astrobiology

  16. CALS Office of Student Services--Career Development Cornell University 140 Roberts Hall Ithaca, NY 14853 www.cals.cornell.edu P: 607/255CALS (2257) F: 607/2544613 calsstudentservices@cornell.edu

    E-print Network

    Angenent, Lars T.

    2257-01-01

    with this pro cess. Evaluate your choices objec vely rela ve to your own personal/professional goals: what. Compara ve salary and cost of living informa on (if choosing between offers). Vaca on and other c, and entertainment ac vi es in the local community. Any "catches," such as a restric ve

  17. Nucleosynthesis and the Chemical Evolution of the Universe

    E-print Network

    Liske, Jochen

    pressure. How does its density, vac, evolve with time? What is the ultimate fate of a universe that has vacAS2001 Nucleosynthesis and the Chemical Evolution of the Universe Tutorial 1 Question 1 Given. Question 2 What is approximately the size of the observable universe? Observations have shown

  18. 1yale environmental NEWS The Yale Peabody Museum of Natural History, the School of Forestry & Environmental Studies, and the Yale Institute for Biospheric Studies

    E-print Network

    of Jackson, and created a vaca- tion site that was "part cattle and part dude ranch" with close proximity for the environment is just very admi- rable." Ordway owns Fish Creek Ranch in Wilson, Wyoming, a 382-acre property Hole Land Trust, on whose board Ordway sat, protects the ranch in perpetuity. Ordway has also supported

  19. AUTOR TITOL DIRECTOR TESIS TUTOR DEPARTAMENT/INSTITUT o

    E-print Network

    Daniilidis, Aris

    , Montserrat Blanco Vaca, Francisco Estudi de Doctorat en Bioquímica, Biologia Molecular i Biomedicina Ferrer, Maria Llugany Olle, Merce Estudi de Doctorat en Biologia i Biotecnologia Vegetal Alvarez de Toledo Biologia Cel·lular Bahamón Garcia, Daniel NEW GENERATION ADSORBENTS FOR GAS SEPARATION: FROM MODELING

  20. High Prevalence of Multiple Strain Colonization of Helicobacter pylori in Korean Patients: DNA Diversity Among Clinical Isolates from the Gastric Corpus, Antrum and Duodenum

    PubMed Central

    Kim, Jeong Wook; Kim, Jae Gyu; Chae, Seok Lae; Cha, Young Joo; Park, Sill Moo

    2004-01-01

    Background : The aims of our study were to determine the correlation of the strain variation and degree of homogeneity of infecting Helicobacter pylori (H. pylori) with their disease outcomes, and the relevance of duodenal H. pylori expression of cagA and/or vacA gene to the development of duodenal ulcer in Korean patients. Methods : One hundred and twenty bacterial colonies isolated from different anatomical sites of the stomach and duodenum were used. The study population was consisted of 40 Korean patients, 21 with duodenal ulcer, 7 with gastric ulcer, 3 with combined gastric and duodenal ulcer, and 9 with chronic gastritis. Genomic characteristics of each strain were analyzed by random amplified polymorphic DNA (RAPD) fingerprinting. The cagA and vacA genes were detected by polymerase chain reaction (PCR). Results : PCR-based RAPD was proved to be a reliable method for the discrimination of individual bacterial genomic characteristics. Genomic fingerprinting showed a varying degree of inter- and intra-patient variation. Thirteen patients (32.5%) were colonized by a single strain throughout the corpus, antrum and duodenum, whereas the other 27 (67.5%) harbored multiple H. pylori strains. Thirty-six isolates (90.0%) each from the corpus and antrum, and 34 (85.0%) from the duodenum, expressed the cagA gene. The prevalence of duodenal H. pylori expression of the cagA gene was not different between patients with chronic gastritis and those with duodenal ulcer. All isolates were positive for both genes vacA s1 and vacA s1a. Conclusion : These results suggested that many of the H. pylori-infected Korean patients were actually colonized with mixed populations of different H. pylori strains and that the prevalence of duodenal H. pylori expression of the cagA and/or vacA gene was not correlated with the development of duodenal ulcer in Korean patients. PMID:15053036

  1. mRNA expression profiling reveals a role of Helicobacter pylori vacuolating toxin in escaping host defense

    PubMed Central

    Yuan, Jian-Ping; Li, Tao; Li, Zhen-Hong; Yang, Gui-Zhen; Hu, Bao-Yu; Shi, Xiao-Dong; Shi, Tie-Liu; Tong, Shan-Qing; Guo, Xiao-Kui

    2004-01-01

    AIM: To study the immune response of host to Helicobacter pylori VacA. METHODS: The monocyte/macrophage-like U937 cells were infected with Helicobacter pylori vacA-positive strain NCTC 11638 or isogenic vacA-negative mutant. Differentially expressed genes were identified at 2, 6, 10, and 24 h post-infection by cDNA microarray. Differential expressions of some genes were confirmed by Northern blot. RESULTS: More than 100 genes altered their mRNA expression at different time points respectively, many of which were identified to be related to immune evasion. CONCLUSION: VacA is a crucial element for H pylori to escape from host immune defense by means of differentially regulating the expression of some related genes. These genes, previously known or unknown to be involved in the mechanism of immune evasion, deserve further investigation to unearth much more information complicated in the immune response. PMID:15133867

  2. Deletion of Helicobacter pylori vacuolating cytotoxin gene by introduction of directed mutagenesis

    PubMed Central

    Yuan, Jian-Ping; Li, Tao; Shi, Xiao-Dong; Hu, Bao-Yu; Yang, Gui-Zhen; Tong, Shan-Qing; Guo, Xiao-Kui

    2003-01-01

    AIM: To construct a vacA-knockout Helicobacter pylori mutant strain, whose only difference from the wild strain is its disrupted vacA gene. METHODS AND RESULTS: A clone containing kanamycin resistance gene used for homologous recombination was constructed in a directional cloning procedure into pBluescript II SK, and then transformed into vacA+ H pylori by electroporation. Colonies growing on the selective media containing kanamycin were harvested for chromosomal DNA extraction, and the allelic exchange was determined by polymerase chain reactions and sequencing. Loss of vacuolating activity of the vacA-knockout strain was confirmed by examining the gastric cells co-cultured with cell-free supernatants from H pylori wild strain or the mutant. CONCLUSION: We constructed a vacA-knockout strain of H pylori through direct mutagenesis, which creates an important precondition for the future research on virulence comparison with gene expression analysis. PMID:14562387

  3. Helicobacter pylori infection in children.

    PubMed

    Vandenplas, Y; Blecker, U

    1998-11-01

    Helicobacter pylori colonizes the human stomach, especially during childhood. However, a variety of H. pylori strains exists, with major differences in virulence characteristics which probably account for different clinical symptoms, and the majority of infected subjects remains asymptomatic. Helicobacter pylori infection is correlated with socioeconomic conditions and hygienic circumstances, resulting in an extremely high prevalence in children in developing countries. Commercial screening tests are not capable of separating the more virulent strains (type I with vacuolating toxin VacA and CagA protein) from the less virulent strains (type II, VacA and CagA negative). Type I strains, but not type II, are associated with an increased risk for duodenal ulcer and gastric cancer. Therefore, future screening tests and vaccinations should focus on the type I strains. PMID:9846909

  4. Cyclostratigraphy of an orbitally-driven Tithonian-Valanginian carbonate ramp succession, Southern Mendoza, Argentina: Implications for the Jurassic-Cretaceous boundary in the Neuquén Basin

    NASA Astrophysics Data System (ADS)

    Kietzmann, Diego A.; Palma, Ricardo M.; Iglesia Llanos, Maria Paula

    2015-01-01

    Detailed sedimentological, sequence stratigraphical and cyclostratigraphical analyses have been made from four lower Tithonian-lower Valanginian sections of the Vaca Muerta Formation, exposed in the southern Mendoza area of the Neuquén Basin, Argentina. The Vaca Muerta Formation is characterized by decimetre-scale rhythmic alternations of marls, shales and limestones, and consists of five facies associations, which reflect different paleoenvironmental conditions: basin to restricted outer ramp, outer ramp, and middle ramp. Vertical organization within the Vaca Muerta Formation shows a well-ordered hierarchy of cycles, where elementary cycles, bundles and superbundles with frequencies within the Milankovitch band have been recognized. According to biostratigraphic data, elementary cycles have a periodicity of ~ 20 ky, which correlates with the precession cycle of Earth's axis. Spectral analysis based on series of cycle thickness allows us to identify frequencies of about 400 ky and 90-120 ky, which we interpret as the modulation of the precessional cycle by the Earth's orbital eccentricity. Cycles are probably driven by variations in carbonate exportation, as fluctuations in shallow-water carbonate production involve modifications in carbonate basinward exportation. Cyclostratigraphic data allowed us to build a floating orbital scale for the Tithonian-lower Valanginian interval in the Neuquén Basin. Correlation between studied sections allowed us to recognize a discontinuity between the Substeueroceras koeneni and Argentiniceras noduliferum ammonite zones in the Malargüe Anticline area. Orbital calibration of these sections is consistent with Riccardi's biostratigraphic scheme, wich place the Jurassic-Cretaceous boundary within the Substeueroceras koeneni ammonite Zone. On the other hand, the base of the Vaca Muerta Formation (Virgatosphinctes mendozanus ammonite Zone) would be probably placed in the base of the middle Tithonian rather than the lower Tithonian, which is also consistent with our preliminary palaeomagnetic data.

  5. 76 FR 18544 - Combined Notice of Filings #2

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-04

    ...-000. Applicants: CalPeak Power LLC, CalPeak Power--Panoche LLC, CalPeak Power--Vaca Dixon, LLC, CalPeak Power--El Cajon LLC, CalPeak Power-- Enterprise LLC, CalPeak Power--Border LLC, Tyr Energy, LLC... Acquisition Report of CalPeak Power LLC. Filed Date: 03/24/2011. Accession Number: 20110324-5028. Comment...

  6. Comparative evaluation of three supplements for Helicobacter pylori growth in liquid culture.

    PubMed

    Douraghi, Masoumeh; Kashani, Samaneh Saberi; Zeraati, Hojjat; Esmaili, Maryam; Oghalaie, Akbar; Mohammadi, Marjan

    2010-04-01

    Helicobacter pylori, a microaerophilic fastidious bacterium, has been cultured on various plating and broth media since its discovery. Although the agar media can be sufficient for the identification, typing, and antibiotic resistance studies, no secretory antigen of H. pylori can be evaluated in such media. Thus, satisfactory growth of H. pylori in liquid culture which is needed for analysis of secretory proteins without the presence of interfering agents is in demand. We assessed the impact of beta-cyclodextrin, Fetal Bovine Serum (FBS), and charcoal as supplements for H. pylori growth. Furthermore, we aimed to identify the most favorable supplement that supports the secretion of the dominant secretory protein, vacuolating cytotoxin (VacA). Five clinical strains were cultured on broth media and the growth, viability, morphology, and protein content of each strain were determined. Our results revealed that beta-cyclodextrin supports the growth rate, viability, and cell lysate protein content to the extent similar to FBS. Application of beta-cyclodextrin is found to postpone spiral to coccoid conversion up to 72 h of incubation. Although FBS supports a higher VacA protein content, presence of interfering macromolecules in FBS questions its utility particularly for purposes of studying extra cellular proteins such as VacA. This study recommends further application of beta-cyclodextrin as a culture supplement with the potential capacity in neutralizing toxic compounds and flourishing the secretion of H. pylori proteins without addition of interfering proteins. PMID:19949795

  7. Red wine and green tea reduce H pylori- or VacA-induced gastritis in a mouse model

    PubMed Central

    Ruggiero, Paolo; Rossi, Giacomo; Tombola, Francesco; Pancotto, Laura; Lauretti, Laura; Del Giudice, Giuseppe; Zoratti, Mario

    2007-01-01

    AIM: To investigate whether red wine and green tea could exert anti-H pylori or anti-VacA activity in vivo in a mouse model of experimental infection. METHODS: Ethanol-free red wine and green tea concentrates were administered orally as a mixture of the two beverages to H pylori infected mice, or separately to VacA-treated mice. Gastric colonization and gastric inflammation were quantified by microbiological, histopathological, and immunohistochemical analyses. RESULTS: In H pylori-infected mice, the red wine and green tea mixture significantly prevented gastritis and limited the localization of bacteria and VacA to the surface of the gastric epithelium. Similarly, both beverages significantly prevented gastric epithelium damage in VacA-treated mice; green tea, but not red wine, also altered the VacA localization in the gastric epithelium. CONCLUSION: Red wine and green tea are able to prevent H pylori-induced gastric epithelium damage, possibly involving VacA inhibition. This observation supports the possible relevance of diet on the pathological outcome of H pylori infection. PMID:17230601

  8. Helicobacter pylori typing as a tool for tracking human migration

    PubMed Central

    Yamaoka, Y.

    2011-01-01

    Helicobacter pylori strains from different geographic areas exhibit clear phylogeographical differentiation; therefore, the genotypes of H. pylori strains can serve as markers for the migration of human populations. Currently, the genotypes of two virulence factors of H. pylori, cagA and vacA, and multilocus sequence typing (MLST) are widely used markers for genomic diversity within H. pylori populations. There are two types of cagA: the East Asian type and the Western type. In addition, the right end of the cag pathogenicity island is divided into five subtypes and there are distinct mosaic structures at the signal region and the middle region of vacA. Using combinations of the cagA, cag right end junction, and vacA genotypes, five major groups (East Asia type, South/Central Asia type, Iberian/Africa type and Europe type) have been defined according to geographical associations. MLST has revealed seven modern population types and six ancestral population types of H. pylori, and is a useful tool for mapping human migration patterns. Serial studies of large numbers of H. pylori strains, including strains isolated from aboriginal populations, show that MLST analysis provides more detailed information on human migration than does the analysis of human genetics. H. pylori infection is rapidly declining as a result of improvements in personal hygiene and quality of life. The molecular epidemiology of H. pylori infection has much to tell us and should be studied before it disappears entirely. PMID:19702588

  9. Protection against Helicobacter pylori infection in mice by intragastric vaccination with H. pylori antigens is achieved using a non-toxic mutant of E. coli heat-labile enterotoxin (LT) as adjuvant.

    PubMed

    Marchetti, M; Rossi, M; Giannelli, V; Giuliani, M M; Pizza, M; Censini, S; Covacci, A; Massari, P; Pagliaccia, C; Manetti, R; Telford, J L; Douce, G; Dougan, G; Rappuoli, R; Ghiara, P

    1998-01-01

    We have previously shown that infection of mice with H. pylori can be prevented by oral immunization with H. pylori antigens given together with E. coli heat-labile enterotoxin (LT) as adjuvant. Since LT cannot be used in humans because of its unacceptable toxicity, we investigated whether protection of mice could be achieved by co-administration of antigens with non-toxic LT mutants. Here we show that CD1/SPF mice are protected against infection after oral vaccination with either purified H. pylori antigens (native and recombinant VacA, urease and CagA), or whole-cell vaccine formulations, given together with the non-toxic mutant LTK63 as a mucosal adjuvant. Furthermore we show that such protection is antigen-specific since immunization with recombinant or native VacA plus LTK63 conferred protection against infection by an H. pylori Type I strain, which expresses VacA, but not against challenge with a Type II strain which is not able to express this antigen. These results show that: (1) protection against H. pylori can be achieved in the mouse model of infection using subunit recombinant constructs plus non-toxic mucosal adjuvants; and (2) this mouse model is an useful tool in testing H. pylori vaccine formulations for eventual use in humans. PMID:9607006

  10. D.G. SCOTT HUBBARD D.G. Scott Hubbard es el Director del Centro de Investigacin de NASA

    E-print Network

    Cardeñosa, Jesús

    D.G. SCOTT HUBBARD D.G. Scott Hubbard es el Director del Centro de Investigación de NASA Ames en Investigación NASA. Previamente a su nombramiento como Director de Ames, fue Vice- Director de Investigación en NASA Ames. Sirvió recientemente como único representante de NASA en la Comisión de Investigación del

  11. UNIVERSIDADE FEDERAL DE SANTA CATARINA CURSO DE PS-GRADUAO

    E-print Network

    Floeter, Sergio Ricardo

    UNIVERSIDADE FEDERAL DE SANTA CATARINA CURSO DE PÓS-GRADUAÇÃO PROCESSO SELETIVO PARA INGRESSO-MAIL FORMAÇÃO ACADÊMICA NA GRADUAÇÃO CURSO ANO DE CONCLUSÃO INSTITUIÇÃO CIDADE UF PAÍS PÓS-GRADUAÇÃO PROGRAMA Agroecossistemas sem haver previamente revalidado seu curso de graduação obtido no exterior, está perfeitamente

  12. UNIVERSIDAD SIMN BOLVAR DIRECCIN DE ADMISIN Y CONTROL DE ESTUDIOS

    E-print Network

    Vásquez, Carlos

    cualquier técnica manual o por computadora, así como ensayos sobre Teoría e Historia de la Arquitectura y a los requeridos deberá ser previamente consultada a la Coordinación de Arquitectura. Es admisible la, deberá ser consultado a la Coordinación de Arquitectura al (212) 906 30 81 #12;

  13. Helicobacter pylori Perturbs Iron Trafficking in the Epithelium to Grow on the Cell Surface

    PubMed Central

    Tan, Shumin; Noto, Jennifer M.; Romero-Gallo, Judith; Peek, Richard M.; Amieva, Manuel R.

    2011-01-01

    Helicobacter pylori (Hp) injects the CagA effector protein into host epithelial cells and induces growth factor-like signaling, perturbs cell-cell junctions, and alters host cell polarity. This enables Hp to grow as microcolonies adhered to the host cell surface even in conditions that do not support growth of free-swimming bacteria. We hypothesized that CagA alters host cell physiology to allow Hp to obtain specific nutrients from or across the epithelial barrier. Using a polarized epithelium model system, we find that isogenic ?cagA mutants are defective in cell surface microcolony formation, but exogenous addition of iron to the apical medium partially rescues this defect, suggesting that one of CagA's effects on host cells is to facilitate iron acquisition from the host. Hp adhered to the apical epithelial surface increase basolateral uptake of transferrin and induce its transcytosis in a CagA-dependent manner. Both CagA and VacA contribute to the perturbation of transferrin recycling, since VacA is involved in apical mislocalization of the transferrin receptor to sites of bacterial attachment. To determine if the transferrin recycling pathway is involved in Hp colonization of the cell surface, we silenced transferrin receptor expression during infection. This resulted in a reduced ability of Hp to colonize the polarized epithelium. To test whether CagA is important in promoting iron acquisition in vivo, we compared colonization of Hp in iron-replete vs. iron-deficient Mongolian gerbils. While wild type Hp and ?cagA mutants colonized iron-replete gerbils at similar levels, ?cagA mutants are markedly impaired in colonizing iron-deficient gerbils. Our study indicates that CagA and VacA act in concert to usurp the polarized process of host cell iron uptake, allowing Hp to use the cell surface as a replicative niche. PMID:21589900

  14. Mutants of TETRAHYMENA THERMOPHILA with Temperature-Sensitive Food Vacuole Formation. I. Isolation and Genetic Characterization

    PubMed Central

    Suhr-Jessen, Peter B.; Orias, Eduardo

    1979-01-01

    Germ-line mutants have been isolated in Tetrahymena thermophila that have recessive, temperature-sensitive defects in phagocytosis. Nitrosoguanidine-mutagenized cells were induced to undergo cytogamy, and clones were isolated that were unable to form food vacuoles after two days of growth at 39°. Most of the mutants belong to a single complementation group, designated vacA. They have defects in oral development—not in phagocytosis per se—that are undetectable under light microscopy. One fertile mutant, phenotypically indistinguishable from the vacA group, has its vac mutation(s) restricted to the macronucleus, and it is a heterokaryon for two other markers. This clone probably resulted from a failure of the two gametic nuclei to fuse after normal exchange. Two additional mutants were studied, but their sterility prevented a full genetic analysis. One of these clones has a rudimentary oral apparatus and defective contractile vacuole pores; both defects may be determined by the same mutation. The other clone has a structurally normal oral apparatus and may be defective in phagocytosis per se.—The induction and characterization of germ-line mutations that affect oral development open the way for the genetic dissection of the morphogenesis of a complex eukaryotic organelle, and make available additional useful mutants for the study of nutrition and transmembrane active transport. PMID:17248939

  15. Isotopic, Chemical and Mineralogical Investigation's of Extraterrestrial Materials

    NASA Technical Reports Server (NTRS)

    Lugmair, G. W.

    2003-01-01

    During the grant period we have concentrated on the following main topics: 1. Enstatite meteorites and original heterogeneity of Mn-53 distribution in the solar nebula. We have completed our studies of the enstatite chondrites. 2. Processes of planetary differentiation. We have completed our study of silicate clasts from the mesosiderite Vaca Muerta and found that the global Mn/Cr fractionation event that established mantle source reservoirs on the parent body of the Vaca Muerta silicate clasts occurred approx. 2 Ma after a similar event on the howardite-eucrite-diogenite (HED) parent body. 3. Carbonaceous chondrites. Much effort has been devoted during the last three years to the investigation of this important class of meteorites. 4. Early solar system timescales. Based on the studies of the Mn-53 - Cr-53 isotope system in various meteorites and using results obtained with other isotope chronometers we constructed an absolute time-scale for events in the early solar system. 5.Unusual meteorites. We have studied the anomalous pallasite Eagle Station. 6. The chromium isotopic composition as a tracer for extraterrestrial material on Earth. Based on the observed difference in the Cr-53/Cr-52 ratios between Earth and the other solar system objects we developed a method for detecting cosmic materials on Earth using the Cr-53/Cr-52 ratio as a tracer.

  16. Immune responses to Helicobacter pylori infection

    PubMed Central

    Moyat, Mati; Velin, Dominique

    2014-01-01

    Helicobacter pylori (H. pylori) infection is one of the most common infections in human beings worldwide. H. pylori express lipopolysaccharides and flagellin that do not activate efficiently Toll-like receptors and express dedicated effectors, such as ?-glutamyl transpeptidase, vacuolating cytotoxin (vacA), arginase, that actively induce tolerogenic signals. In this perspective, H. pylori can be considered as a commensal bacteria belonging to the stomach microbiota. However, when present in the stomach, H. pylori reduce the overall diversity of the gastric microbiota and promote gastric inflammation by inducing Nod1-dependent pro-inflammatory program and by activating neutrophils through the production of a neutrophil activating protein. The maintenance of a chronic inflammation in the gastric mucosa and the direct action of virulence factors (vacA and cytotoxin-associated gene A) confer pro-carcinogenic activities to H. pylori. Hence, H. pylori cannot be considered as symbiotic bacteria but rather as part of the pathobiont. The development of a H. pylori vaccine will bring health benefits for individuals infected with antibiotic resistant H. pylori strains and population of underdeveloped countries. PMID:24914318

  17. Mutants of TETRAHYMENA THERMOPHILA with Temperature-Sensitive Food Vacuole Formation. I. Isolation and Genetic Characterization.

    PubMed

    Suhr-Jessen, P B; Orias, E

    1979-08-01

    Germ-line mutants have been isolated in Tetrahymena thermophila that have recessive, temperature-sensitive defects in phagocytosis. Nitrosoguanidine-mutagenized cells were induced to undergo cytogamy, and clones were isolated that were unable to form food vacuoles after two days of growth at 39 degrees . Most of the mutants belong to a single complementation group, designated vacA. They have defects in oral development-not in phagocytosis per se-that are undetectable under light microscopy. One fertile mutant, phenotypically indistinguishable from the vacA group, has its vac mutation(s) restricted to the macronucleus, and it is a heterokaryon for two other markers. This clone probably resulted from a failure of the two gametic nuclei to fuse after normal exchange. Two additional mutants were studied, but their sterility prevented a full genetic analysis. One of these clones has a rudimentary oral apparatus and defective contractile vacuole pores; both defects may be determined by the same mutation. The other clone has a structurally normal oral apparatus and may be defective in phagocytosis per se.-The induction and characterization of germ-line mutations that affect oral development open the way for the genetic dissection of the morphogenesis of a complex eukaryotic organelle, and make available additional useful mutants for the study of nutrition and transmembrane active transport. PMID:17248939

  18. Preliminary design of a special casing joint for a well equipped twin horizontal drainholes in the Oxnard field

    SciTech Connect

    Not Available

    1993-12-31

    The Oxnard field is presently under production,with a typical average monthly oil production of about 70,000 B, of which the Vaca Tar sand represents more than half.It is Unitized and operated under cyclic steam injection.The hot Tar and produced water are lifted to the surface with rod pumps equipped for injection of a diluent. The produced WOR is about 2.5 and the GOR is about 150 scf/B. The Vaca Tar sand originally contained about 400 million STB. The estimated recoverable reserve under full-scale cyclic steam injection is 100 to 120 Million STB. Under steamflood, it might reach 240 million STB. The objectives of this field test are: (1) increase well productivity by using a vertical well equipped with twin horizontal drainholes, each of about 1,000 ft. reach; (2) maximize the well draw-down by locating the horizontal wells near the base of the sand layer; (3) reduce capital cost by using twin drainholes connected to the same vertical cased well; (4) reduce operating expenses by eliminating the need for a service rig to pull-out the rods and pump before each steam injection cycle; and (5) be adaptable to other operating modes.

  19. Serum Antibodies Positivity to 12 Helicobacter pylori Virulence Antigens in Patients with Benign or Malignant Gastroduodenal Diseases – Cross-sectional Study

    PubMed Central

    Filipec Kanižaj, Tajana; Kati?i?, Miroslava; Prese?ki, Vladimir; Gašparov, Slavko; Coli? Cvrlje, Vesna; Kolari?, Branko; Mrzljak, Anna

    2009-01-01

    Aim To investigate the association of gastric histological and endoscopic findings in patients with Helicobacter pylori (H. pylori), according to presence of seropositivity to 12 bacterial virulence antigens. Methods This is a cross-sectional single-center study of 360 consecutive outpatients referred in the period of one year to upper gastrointestinal endoscopy because of dyspeptic complaints. Patients sera were tested by Western blot method to determine the presence of serum antibodies to bacterial virulence antigens – p120 (CagA – cytotoxin-associated antigen), p95 (VacA – vacuolating cytotoxin), p67 (FSH – flagellar sheath protein), p66 (UreB – urease enzyme heavy subunit), p57 (HSP homologue – heath shock protein homologue), p54 (flagellin), p33, p30 (OMP – outer membrane protein), p29 (UreA – urease enzyme light subunit), p26, p19, and p17. Upper gastrointestinal endoscopy was performed, endoscopic diagnosis recorded, and 4 mucosal biopsy samples were obtained and assessed according to Updated Sydney protocol. Results The sera of 207 patients were analyzed. Thirty patients had gastric adenocarcinoma, 126 peptic ulcers, and 51 normal finding. p120 (CagA) seropositivity was significantly more often present in patients with higher activity grade in the antrum (P?=?0.025), p30 in patients with greater inflammation in the antrum (P?=?0.025) and the corpus (P?=?0.010), p33 in patients with greater inflammation in the corpus (P?=?0.050), and p19 (OMP) in patients with lower intestinal metaplasia grades in the corpus (P?=?0.025). Seroreactivity to all other bacterial proteins showed no association with the histological status of the stomach mucosa. Except for the seropositivity to protein p95 (VacA), which was more often present in patients with duodenal ulcer (P?=?0.006), there was no difference in seroreactivity to other bacterial proteins and upper gastrointestinal endoscopic findings. Conclusions p120 (CagA), p33, p 30 (OMP), and p19 (OMP) seropositivity was more often present in patients with higher grades of the histological parameters of gastritis and seropositivity to protein p95 (VacA) with endoscopic presence of duodenal ulcer. Histological parameters of gastritis are more associated with bacterial virulence than endoscopic findings. PMID:19399945

  20. A late Jurassic pterosaur (Reptilia, Pterodactyloidea) from northwestern Patagonia, Argentina

    NASA Astrophysics Data System (ADS)

    Codorniú, Laura; Gasparini, Zulma; Paulina-Carabajal, Ariana

    2006-03-01

    A small to medium-sized pterodactyloid pterosaur (wingspan approximately 1.10 m) from the Upper Jurassic (middle-late Tithonian) marine deposits of the Vaca Muerta Formation of Patagonia (Los Catutos area, central Neuquén Province, Argentina) is reported. The specimen lacks the skull but constitutes a nearly complete postcranial skeleton, which includes cervical and dorsal vertebrae; a few thoracic ribs; both pectoral girdles; the left pelvic girdle; a proximal right wing (humerus, ulna, and radius) and metacarpal IV; a left wing that lacks only wing phalanx four; and both hindlimbs, the right one without the foot. Ontogenetic features suggest that the new fossil corresponds to a relatively mature individual, probably a subadult. Observed characters support its assignment to the Archaeopteroactyloidea, a basal clade within the Pterodactyloidea. This specimen is the second pterosaur from Los Catutos and the most complete Jurassic pterosaur so far known from South America.

  1. Classification of mafic clasts from mesosiderites - Implications for endogenous igneous processes

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.; Mittlefehldt, David W.

    1992-01-01

    Results are presented from an analysis of 13 igneous pebbles from the Vaca Muerta, EET87500, and Bondoc mesosiderites, using electron microprobe and instrumental neutron activation techniques. These data, combined with literature data on compositions of 43 mesosiderite clasts were used to compile a classification scheme for the various types of mafic silicate clasts that occur in mesosiderites. These clasts were classified into five principal groups: (1) polygenic and monogenic cumulates (30 percent); (2) polygenic basalts (30 percent); (3) quench-textured rocks, comprising two compositional subgroups (those which resemble basaltic eucrites (5 percent), and those which resemble cumulate eucrites (2 percent)); (4) monogenic basalts (11 percent); and (5) ultramafic rocks, consisting mainly of large crystals of orthopyroxene (9 percent) or olivine (4 percent). The conditions under which these clasts were formed are discussed.

  2. Historical descriptions of some soils and landscapes of Texas

    NASA Astrophysics Data System (ADS)

    Schulze, Darrell G.

    Europeans explorers, immigrants, and travelers have been crisscrossing Texas for almost 5 centuries, recording their observations of soils and landscapes through the lens of their own times. In the early 16th century, Cabeza de Vaca was struck by how the natives among whom he lived used soil as a part of their diet. In the 17th century, as a member of the La Salle expedition to Texas, Henri Joutel described the soils and landscapes he saw in considerable detail, perhaps with an eye to possible future French settlement. To 19th century immigrants, the soil was the source of their future wealth, but also, so they thought, of the source of the various illnesses that inflicted them. With their distinctive micro-topography and large cracks when dry, Vertisols have elicited some of the most interesting early descriptions of Texas soils.

  3. Diet, microbial virulence, and Helicobacter pylori-induced gastric cancer

    PubMed Central

    Cover, Timothy L; Peek, Jr, Richard M

    2013-01-01

    Gastric adenocarcinoma is a leading cause of cancer-related death worldwide, and Helicobacter pylori infection is one of the strongest known risk factors for this malignancy. H. pylori strains exhibit a high level of genetic diversity, and the risk of gastric cancer is higher in persons carrying certain strain types (for example, those that contain a cag pathogenicity island or type s1 vacA alleles) than in persons carrying other strain types. Additional risk factors for gastric cancer include specific human genetic polymorphisms and specific dietary preferences (for example, a high-salt diet or a diet deficient in fruits and vegetables). Finally, iron-deficiency anemia is a risk factor for gastric cancer. Recent studies have provided evidence that several dietary risk factors for gastric cancer directly impact H. pylori virulence. In this review article, we discuss mechanisms by which diet can modulate H. pylori virulence and thereby influence gastric cancer risk. PMID:23989802

  4. Fotometría y polarimetría de Lynga 1

    NASA Astrophysics Data System (ADS)

    Brusasco, M. A.; Baume, G.; Vázquez, R. A.

    Se presentan los resultados de las observaciones fotométricas CCD-UBVRI hasta magnitud aproximadamente V = 18 y polarimétricas hasta V = 13 en la zona del cúmulo abierto Lynga 1. El mismo se halla en una dirección cercana a un remanente de supernova y fue estudiado previamente por Peterson y FitzGerald (1988) mediante fotometría fotoeléctrica. Se ha redeterminado el enrojecimiento, la distancia y la edad de dicho objeto. Se han hallado además los valores de las pendientes de las funciones de luminosidad y de masa comparándoselas con las de otros cúmulos de edades similares.

  5. Fotometría y polarimetría de Trumpler 21

    NASA Astrophysics Data System (ADS)

    Giorgi, E.; Baume, G.; Vázquez, R. A.

    Se presentan los resultados de las observaciones fotométricas CCD-UBVI hasta aproximadamente magnitud V = 19 y polarimétricas UBVRI hasta V =13 en la región del cúmulo abierto Trumpler 21. El mismo se halla en una dirección cercana al remanente de supernova G307.6-0.3 y fue estudiado previamente por Moffat y Vogt (1973) y por Peterson y FitzGerald (1988) mediante fotometría fotoeléctrica de las estrellas más brillantes. Se ha redeterminado el enrojecimiento, la distancia y la edad de dicho objeto. Se han hallado además los valores de las pendientes de las funciones de luminosidad y de masa comparandoselas con las de otros cúmulos de edades similares.

  6. Food Safety for Tailgate Parties and Picnics (Spanish) 

    E-print Network

    Van Laanen, Peggy

    2001-10-22

    pueden caer en la zona de peligro a?n cuando el clima est? fresco. ?Qu? alimentos producen riesgos? Casi cualquier ali- mento puede ser una fuente de bacterias peligrosas, pero los alimentos m?s peligrosos son los que son h?medos y contienen prote... de 40 grados F. Empaque los ali- mentos en recipientes que no sean hondos y cong?le- los previamente antes de colocarlos en la hielera. Mantenga los sandwiches helados o c?malos dentro de 2 horas. Vigile el reloj en cuanto a las comidas que est...

  7. Serological response to Helicobacter pylori infection among Latin American populations with contrasting risks of gastric cancer.

    PubMed

    Camargo, M Constanza; Beltran, Mauricio; Conde-Glez, Carlos J; Harris, Paul R; Michel, Angelika; Waterboer, Tim; Carolina Flórez, Astrid; Torres, Javier; Ferreccio, Catterina; Sampson, Joshua N; Pawlita, Michael; Rabkin, Charles S

    2015-12-15

    Gastric cancer is a rare outcome of chronic Helicobacter pylori infection. Serologic profiles may reveal bacterial, environmental and/or host factors associated with cancer risk. We therefore compared specific anti-H. pylori antibodies among populations with at least twofold differences in gastric cancer mortality from Mexico, Colombia and Chile. Our study included 1,776 adults (mean age 42 years) from three nationally representative surveys, equally divided between residents of high- and low-risk areas. Antibodies to 15 immunogenic H. pylori antigens were measured by fluorescent bead-based multiplex assays; results were summarized to identify overall H. pylori seropositivity. We used logistic regression to model associations between antibody seroreactivity and regional cancer risk (high vs. low), adjusting for country, age and sex. Both risk areas had similar H. pylori seroprevalence. Residents in high- and low-risk areas were seroreactive to a similar number of antigens (means 8.2 vs. 7.9, respectively; adjusted odds ratio, OR: 1.02, p?=?0.05). Seroreactivities to Catalase and the known virulence proteins CagA and VacA were each significantly (p?VacA. Sensitivity analyses for antibody associations restricted to H. pylori-seropositive individuals generally replicated significant associations. Our findings suggest that humoral responses to H. pylori are insufficient to distinguish high and low gastric cancer risk in Latin America. Factors determining population variation of gastric cancer burden remain to be identified. PMID:26178251

  8. Comparison of Storage Capacity and Sedimentation Trends of Lago Guayabal, Puerto Rico-December 2001 and October 2006

    USGS Publications Warehouse

    Soler-López, Luis R.

    2008-01-01

    Lago Guayabal dam is located on the Rio Jacaguas in the municipality of Villalba in southern Puerto Rico, about 4 kilometers north of the town of Juana Diaz and about 5 kilometers south of Villalba (fig. 1). The dam is owned and operated by the Puerto Rico Electric Power Authority (PREPA) and was constructed in 1913 for the irrigation of croplands in the southern coastal plains of Puerto Rico. The reservoir impounds the waters of the Rio Jacaguas and those of the Rio Toa Vaca, when the Toa Vaca dam overflows or releases water. The reservoir has a drainage area of 53.8 square kilometers. The dam is a concrete gravity structure with a normal pool (at top of flashboards) elevation of 103.94 meters above mean sea level (Puerto Rico Electric Power Authority, 1988). During October 2006, the U.S. Geological Survey (USGS), Caribbean Water Science Center, in cooperation with the Puerto Rico Aqueduct and Sewer Authority (PRASA) conducted a bathymetric survey of Lago Guayabal to update the reservoir storage capacity and actualize the reservoir sedimentation rate by comparing the 2006 data with the previous 2001 bathymetric survey results. The purpose of this report is to describe and document the USGS sedimentation survey conducted at Lago Guayabal during October 2006, including the methods used to update the reservoir storage capacity, sedimentation rates, and areas of substantial sediment accumulation since December 2001. The Lago Guayabal sedimentation history up to 2001 was published by the USGS in 2003 (Soler-Lopez, 2003); therefore, this report focuses on the comparison between the 2001 and current bathymetric surveys of Lago Guayabal.

  9. Sequence Divergence and Conservation in Genomes of Helicobacter cetorum Strains from a Dolphin and a Whale

    PubMed Central

    Kersulyte, Dangeruta; Rossi, Mirko; Berg, Douglas E.

    2013-01-01

    Background and Objectives Strains of Helicobacter cetorum have been cultured from several marine mammals and have been found to be closely related in 16 S rDNA sequence to the human gastric pathogen H. pylori, but their genomes were not characterized further. Methods The genomes of H. cetorum strains from a dolphin and a whale were sequenced completely using 454 technology and PCR and capillary sequencing. Results These genomes are 1.8 and 1.95 mb in size, some 7–26% larger than H. pylori genomes, and differ markedly from one another in gene content, and sequences and arrangements of shared genes. However, each strain is more related overall to H. pylori and its descendant H. acinonychis than to other known species. These H. cetorum strains lack cag pathogenicity islands, but contain novel alleles of the virulence-associated vacuolating cytotoxin (vacA) gene. Of particular note are (i) an extra triplet of vacA genes with ?50% protein-level identity to each other in the 5? two-thirds of the gene needed for host factor interaction; (ii) divergent sets of outer membrane protein genes; (iii) several metabolic genes distinct from those of H. pylori; (iv) genes for an iron-cofactored urease related to those of Helicobacter species from terrestrial carnivores, in addition to genes for a nickel co-factored urease; and (v) members of the slr multigene family, some of which modulate host responses to infection and improve Helicobacter growth with mammalian cells. Conclusions Our genome sequence data provide a glimpse into the novelty and great genetic diversity of marine helicobacters. These data should aid further analyses of microbial genome diversity and evolution and infection and disease mechanisms in vast and often fragile ocean ecosystems. PMID:24358262

  10. Comparative Analysis of the Full Genome of Helicobacter pylori Isolate Sahul64 Identifies Genes of High Divergence

    PubMed Central

    Lu, Wei; Wise, Michael J.; Tay, Chin Yen; Windsor, Helen M.; Marshall, Barry J.; Peacock, Christopher

    2014-01-01

    Isolates of Helicobacter pylori can be classified phylogeographically. High genetic diversity and rapid microevolution are a hallmark of H. pylori genomes, a phenomenon that is proposed to play a functional role in persistence and colonization of diverse human populations. To provide further genomic evidence in the lineage of H. pylori and to further characterize diverse strains of this pathogen in different human populations, we report the finished genome sequence of Sahul64, an H. pylori strain isolated from an indigenous Australian. Our analysis identified genes that were highly divergent compared to the 38 publically available genomes, which include genes involved in the biosynthesis and modification of lipopolysaccharide, putative prophage genes, restriction modification components, and hypothetical genes. Furthermore, the virulence-associated vacA locus is a pseudogene and the cag pathogenicity island (cagPAI) is not present. However, the genome does contain a gene cluster associated with pathogenicity, including dupA. Our analysis found that with the addition of Sahul64 to the 38 genomes, the core genome content of H. pylori is reduced by approximately 14% (?170 genes) and the pan-genome has expanded from 2,070 to 2,238 genes. We have identified three putative horizontally acquired regions, including one that is likely to have been acquired from the closely related Helicobacter cetorum prior to speciation. Our results suggest that Sahul64, with the absence of cagPAI, highly divergent cell envelope proteins, and a predicted nontransportable VacA protein, could be more highly adapted to ancient indigenous Australian people but with lower virulence potential compared to other sequenced and cagPAI-positive H. pylori strains. PMID:24375107

  11. Multiplex-PCR-Based Screening and Computational Modeling of Virulence Factors and T-Cell Mediated Immunity in Helicobacter pylori Infections for Accurate Clinical Diagnosis

    PubMed Central

    Oktem-Okullu, Sinem; Tiftikci, Arzu; Saruc, Murat; Cicek, Bahattin; Vardareli, Eser; Tozun, Nurdan; Kocagoz, Tanil; Sezerman, Ugur; Yavuz, Ahmet Sinan; Sayi-Yazgan, Ayca

    2015-01-01

    The outcome of H. pylori infection is closely related with bacteria's virulence factors and host immune response. The association between T cells and H. pylori infection has been identified, but the effects of the nine major H. pylori specific virulence factors; cagA, vacA, oipA, babA, hpaA, napA, dupA, ureA, ureB on T cell response in H. pylori infected patients have not been fully elucidated. We developed a multiplex- PCR assay to detect nine H. pylori virulence genes with in a three PCR reactions. Also, the expression levels of Th1, Th17 and Treg cell specific cytokines and transcription factors were detected by using qRT-PCR assays. Furthermore, a novel expert derived model is developed to identify set of factors and rules that can distinguish the ulcer patients from gastritis patients. Within all virulence factors that we tested, we identified a correlation between the presence of napA virulence gene and ulcer disease as a first data. Additionally, a positive correlation between the H. pylori dupA virulence factor and IFN-?, and H. pylori babA virulence factor and IL-17 was detected in gastritis and ulcer patients respectively. By using computer-based models, clinical outcomes of a patients infected with H. pylori can be predicted by screening the patient's H. pylori vacA m1/m2, ureA and cagA status and IFN-? (Th1), IL-17 (Th17), and FOXP3 (Treg) expression levels. Herein, we report, for the first time, the relationship between H. pylori virulence factors and host immune responses for diagnostic prediction of gastric diseases using computer—based models. PMID:26287606

  12. The Primary Resistance of Helicobacter pylori in Taiwan after the National Policy to Restrict Antibiotic Consumption and Its Relation to Virulence Factors—A Nationwide Study

    PubMed Central

    Chen, Mei-Jyh; Chen, Chieh-Chang; Fang, Yu-Jen; Lee, Ji-Yuh; Wu, Jeng-Yih; Luo, Jiing-Chyuan; Liou, Tai-Cherng; Chang, Wen-Hsiung; Tseng, Cheng-Hao; Wu, Chun-Ying; Yang, Tsung-Hua; Chang, Chun-Chao; Wang, Hsiu?Po; Sheu, Bor-Shyang; Lin, Jaw-Town; Bair, Ming-Jong; Wu, Ming-Shiang

    2015-01-01

    Objective The Taiwan Government issued a policy to restrict antimicrobial usage since 2001. We aimed to assess the changes in the antibiotic consumption and the primary resistance of H. pylori after this policy and the impact of virulence factors on resistance. Methods The defined daily dose (DDD) of antibiotics was analyzed using the Taiwan National Health Insurance (NHI) research database. H. pylori strains isolated from treatment naïve (N=1395) and failure from prior eradication therapies (N=360) from 9 hospitals between 2000 and 2012 were used for analysis. The minimum inhibitory concentration was determined by agar dilution test. Genotyping for CagA and VacA was determined by PCR method. Results The DDD per 1000 persons per day of macrolides reduced from 1.12 in 1997 to 0.19 in 2008, whereas that of fluoroquinolones increased from 0.12 in 1997 to 0.35 in 2008. The primary resistance of amoxicillin, clarithromycin, metronidazole, and tetracycline remained as low as 2.2%, 7.9%, 23.7%, and 1.9% respectively. However, the primary levofloxacin resistance rose from 4.9% in 2000–2007 to 8.3% in 2008–2010 and 13.4% in 2011–2012 (p=0.001). The primary resistance of metronidazole was higher in females than males (33.1% vs. 18.8%, p<0.001), which was probably attributed to the higher consumption of nitroimidazole. Neither CagA nor VacA was associated with antibiotic resistance. Conclusions The low primary clarithromycin and metronidazole resistance of H. pylori in Taiwan might be attributed to the reduced consumption of macrolides and nitroimidazole after the national policy to restrict antimicrobial usage. Yet, further strategies are needed to restrict the consumption of fluoroquinolones in the face of rising levofloxacin resistance. PMID:25942450

  13. Molecular Epidemiology of Helicobacter pylori Infection in Nepal: Specific Ancestor Root

    PubMed Central

    Miftahussurur, Muhammad; Sharma, Rabi Prakash; Shrestha, Pradeep Krishna; Suzuki, Rumiko; Uchida, Tomohisa; Yamaoka, Yoshio

    2015-01-01

    Prevalence of Helicobacter pylori infection in Nepal, a low-risk country for gastric cancer, is debatable. To our knowledge, no studies have examined H. pylori virulence factors in Nepal. We determined the prevalence of H. pylori infection by using three different tests, and the genotypes of virulence factors were determined by PCR followed by sequencing. Multilocus sequence typing was used to analyze the population structure of the Nepalese strains. The prevalence of H. pylori infection in dyspeptic patients was 38.4% (56/146), and was significantly related with source of drinking water. In total, 51 strains were isolated and all were cagA-positive. Western-type-cagA (94.1%), cagA pre-EPIYA type with no deletion (92.2%), vacA s1a (74.5%), and m1c (54.9%) were the predominant genotypes. Antral mucosal atrophy levels were significantly higher in patients infected with vacA s1 than in those infected with s2 genotypes (P = 0.03). Several Nepalese strains were H. pylori recombinants with genetic features of South Asian and East Asian genotypes. These included all East-Asian-type-cagA strains, with significantly lesser activity and inflammation in the corpus than the strains of the specific South Asian genotype (P = 0.03 and P = 0.005, respectively). Although the population structure confirmed that most Nepalese strains belonged to the hpAsia2 population, some strains shared hpEurope- and Nepalese-specific components. Nepalese patients infected with strains belonging to hpEurope showed higher inflammation in the antrum than strains from the Nepalese specific population (P = 0.05). These results support that ancestor roots of Kathmandu`s people not only connected with India alone. PMID:26226153

  14. Medicinal plant activity on Helicobacter pylori related diseases.

    PubMed

    Wang, Yuan-Chuen

    2014-08-14

    More than 50% of the world population is infected with Helicobacter pylori (H. pylori). The bacterium highly links to peptic ulcer diseases and duodenal ulcer, which was classified as a group?I?carcinogen in 1994 by the WHO. The pathogenesis of H. pylori is contributed by its virulence factors including urease, flagella, vacuolating cytotoxin A (VacA), cytotoxin-associated gene antigen (Cag A), and others. Of those virulence factors, VacA and CagA play the key roles. Infection with H. pylori vacA-positive strains can lead to vacuolation and apoptosis, whereas infection with cagA-positive strains might result in severe gastric inflammation and gastric cancer. Numerous medicinal plants have been reported for their anti-H. pylori activity, and the relevant active compounds including polyphenols, flavonoids, quinones, coumarins, terpenoids, and alkaloids have been studied. The anti-H. pylori action mechanisms, including inhibition of enzymatic (urease, DNA gyrase, dihydrofolate reductase, N-acetyltransferase, and myeloperoxidase) and adhesive activities, high redox potential, and hydrophilic/hydrophobic natures of compounds, have also been discussed in detail. H. pylori-induced gastric inflammation may progress to superficial gastritis, atrophic gastritis, and finally gastric cancer. Many natural products have anti-H. pylori-induced inflammation activity and the relevant mechanisms include suppression of nuclear factor-?B and mitogen-activated protein kinase pathway activation and inhibition of oxidative stress. Anti-H. pylori induced gastric inflammatory effects of plant products, including quercetin, apigenin, carotenoids-rich algae, tea product, garlic extract, apple peel polyphenol, and finger-root extract, have been documented. In conclusion, many medicinal plant products possess anti-H. pylori activity as well as an anti-H. pylori-induced gastric inflammatory effect. Those plant products have showed great potential as pharmaceutical candidates for H. pylori eradication and H. pylori induced related gastric disease prevention. PMID:25132753

  15. Instrumental Role of Helicobacter pylori ?-Glutamyl Transpeptidase in VacA-Dependent Vacuolation in Gastric Epithelial Cells

    PubMed Central

    Ling, Samantha Shi Min; Khoo, Lawrence Han Boon; Hwang, Le-Ann; Yeoh, Khay Guan; Ho, Bow

    2015-01-01

    Helicobacter pylori causes cellular vacuolation in host cells, a cytotoxic event attributed to vacuolating cytotoxin (VacA) and the presence of permeant weak bases such as ammonia. We report here the role of ?-glutamyl transpeptidase (GGT), a constitutively expressed secretory enzyme of H. pylori, in potentiating VacA-dependent vacuolation formation in H. pylori-infected AGS and primary gastric cells. The enhancement is brought about by GGT hydrolysing glutamine present in the extracellular medium, thereby releasing ammonia which accentuates the VacA-induced vacuolation. The events of vacuolation in H. pylori wild type (WT)- and ?ggt-infected AGS cells were first captured and visualized by real-time phase-contrast microscopy where WT was observed to induce more vacuoles than ?ggt. By using semi-quantitative neutral red uptake assay, we next showed that ?ggt induced significantly less vacuolation in AGS and primary gastric epithelial cells as compared to the parental strain (P<0.05) indicating that GGT potentiates the vacuolating effect of VacA. Notably, vacuolation induced by WT was significantly reduced in the absence of GGT substrate, glutamine (P<0.05) or in the presence of a competitive GGT inhibitor, serine-borate complex. Furthermore, the vacuolating ability of ?ggt was markedly restored when co-incubated with purified recombinant GGT (rGGT), although rGGT itself did not induce vacuolation independently. Similarly, the addition of exogenous ammonium chloride as a source of ammonia also rescued the ability of ?ggt to induce vacuolation. Additionally, we also show that monoclonal antibodies against GGT effectively inhibited GGT activity and successfully suppressed H. pylori-induced vacuolation. Collectively, our results clearly demonstrate that generation of ammonia by GGT through glutamine hydrolysis is responsible for enhancing VacA-dependent vacuolation. Our findings provide a new perspective on GGT as an important virulence factor and a promising target in the management of H. pylori-associated gastric diseases. PMID:26111186

  16. Medicinal plant activity on Helicobacter pylori related diseases

    PubMed Central

    Wang, Yuan-Chuen

    2014-01-01

    More than 50% of the world population is infected with Helicobacter pylori (H. pylori). The bacterium highly links to peptic ulcer diseases and duodenal ulcer, which was classified as a group?I?carcinogen in 1994 by the WHO. The pathogenesis of H. pylori is contributed by its virulence factors including urease, flagella, vacuolating cytotoxin A (VacA), cytotoxin-associated gene antigen (Cag A), and others. Of those virulence factors, VacA and CagA play the key roles. Infection with H. pylori vacA-positive strains can lead to vacuolation and apoptosis, whereas infection with cagA-positive strains might result in severe gastric inflammation and gastric cancer. Numerous medicinal plants have been reported for their anti-H. pylori activity, and the relevant active compounds including polyphenols, flavonoids, quinones, coumarins, terpenoids, and alkaloids have been studied. The anti-H. pylori action mechanisms, including inhibition of enzymatic (urease, DNA gyrase, dihydrofolate reductase, N-acetyltransferase, and myeloperoxidase) and adhesive activities, high redox potential, and hydrophilic/hydrophobic natures of compounds, have also been discussed in detail. H. pylori-induced gastric inflammation may progress to superficial gastritis, atrophic gastritis, and finally gastric cancer. Many natural products have anti-H. pylori-induced inflammation activity and the relevant mechanisms include suppression of nuclear factor-?B and mitogen-activated protein kinase pathway activation and inhibition of oxidative stress. Anti-H. pylori induced gastric inflammatory effects of plant products, including quercetin, apigenin, carotenoids-rich algae, tea product, garlic extract, apple peel polyphenol, and finger-root extract, have been documented. In conclusion, many medicinal plant products possess anti-H. pylori activity as well as an anti-H. pylori-induced gastric inflammatory effect. Those plant products have showed great potential as pharmaceutical candidates for H. pylori eradication and H. pylori induced related gastric disease prevention. PMID:25132753

  17. Infection with CagA-positive Helicobacter pylori strain containing three EPIYA C phosphorylation sites is associated with more severe gastric lesions in experimentally infected Mongolian gerbils (Meriones unguiculatus).

    PubMed

    Ferreira Júnior, M; Batista, S A; Vidigal, P V T; Cordeiro, A A C; Oliveira, F M S; Prata, L O; Diniz, A E T; Barral, C M; Barbuto, R C; Gomes, A D; Araújo, I D; Queiroz, D M M; Caliari, M V

    2015-01-01

    Infection with Helicobacter pylori strains containing high number of EPIYA-C phosphorylation sites in the CagA is associated with significant gastritis and increased risk of developing pre-malignant gastric lesions and gastric carcinoma. However, these findings have not been reproduced in animal models yet. Therefore, we investigated the effect on the gastric mucosa of Mongolian gerbil (Meriones unguiculatus) infected with CagA-positive H. pylori strains exhibiting one or three EPIYA-C phosphorilation sites. Mongolian gerbils were inoculated with H. pylori clonal isolates containing one or three EPIYA-C phosphorylation sites. Control group was composed by uninfected animals challenged with Brucella broth alone. Gastric fragments were evaluated by the modified Sydney System and digital morphometry. Clonal relatedness between the isolates was considered by the identical RAPD-PCR profiles and sequencing of five housekeeping genes, vacA i/d region and of oipA. The other virulence markers were present in both isolates (vacA s1i1d1m1, iceA2, and intact dupA). CagA of both isolates was translocated and phosphorylated in AGS cells. After 45 days of infection, there was a significant increase in the number of inflammatory cells and in the area of the lamina propria in the infected animals, notably in those infected by the CagA-positive strain with three EPIYA-C phosphorylation sites. After six months of infection, a high number of EPIYA-C phosphorylation sites was associated with progressive increase in the intensity of gastritis and in the area of the lamina propria. Atrophy, intestinal metaplasia, and dysplasia were also observed more frequently in animals infected with the CagA-positive isolate with three EPIYA-C sites.  We conclude that infection with H. pylori strain carrying a high number of CagA EPIYA-C phosphorylation sites is associated with more severe gastric lesions in an animal model of H. pylori infection. PMID:26150158

  18. Radial patterns of bitumen dykes around Quaternary volcanoes, provinces of northern Neuquén and southernmost Mendoza, Argentina

    NASA Astrophysics Data System (ADS)

    Cobbold, Peter R.; Ruffet, Gilles; Leith, Leslie; Loseth, Helge; Rodrigues, Nuno; Leanza, Hector A.; Zanella, Alain

    2014-12-01

    Where the Neuquén Basin of Argentina abuts the Andes, hundreds of veins of solid hydrocarbon (bitumen) are visible at the surface. Many of these veins became mines, especially in the last century. By consensus, the bitumen has resulted from maturation of organic-rich shales, especially the Vaca Muerta Fm of Late Jurassic age, but also the Agrio Fm of Early Cretaceous age. To account for their maturation, recent authors have invoked regional subsidence, whereas early geologists invoked magmatic activity. During 12 field seasons (since 1998), we have tracked down the bitumen localities, mapped the veins and host rocks, sampled them, studied their compositions, and dated some of them. In the provinces of northern Neuquén and southernmost Mendoza, the bitumen veins are mostly sub-vertical dykes. They tend to be straight and continuous, crosscutting regional structures and strata of all ages, from Jurassic to Palaeocene. Most of the localities lie within 70 km of Tromen volcano, although four are along the Rio Colorado fault zone and another two are at the base of Auca Mahuida volcano. On both volcanic edifices, lavas are of late Pliocene to Pleistocene age. Although regionally many of the bitumen dykes tend to track the current direction of maximum horizontal tectonic stress (ENE), others do not. However, most of the dykes radiate outward from the volcanoes, especially Tromen. Thicknesses of dykes tend to be greatest close to Tromen and where the host rocks are the most resistant to fracturing. Many of the dykes occur in the exhumed hanging walls of deep thrusts, especially at the foot of Tromen. Here the bitumen is in places of high grade (impsonite), whereas further out it tends to be of medium grade (grahamite). A few bitumen dykes contain fragments of Vaca Muerta shale, so that we infer forceful expulsion of source rock. At Curacó Mine, some shale fragments contain bedding-parallel veins of fibrous calcite (beef) and these contain some bitumen, which is geochemically of low grade. In contrast, a large crosscutting bitumen dyke is of higher grade and formed later. At other localities, near basement faults, bitumen dykes have cap-rocks of hydrothermal calcrete. Other dykes or their wall rocks contain hydrothermal minerals. Finally, some dykes splay upward towards the current land surface. We conclude that (1) the bitumen dykes formed during volcanic activity in Pliocene-Pleistocene times, and that (2) heat advection by hydrothermal fluids helped to generate oil, which migrated upwards or downwards from the source rock and filled intrusive veins, before solidifying to bitumen, by loss of volatile elements. This unconventional hydrocarbon system may have significant implications for regional exploration in the foothills of the Andes.

  19. Evolution in an oncogenic bacterial species with extreme genome plasticity: Helicobacter pylori East Asian genomes

    PubMed Central

    2011-01-01

    Background The genome of Helicobacter pylori, an oncogenic bacterium in the human stomach, rapidly evolves and shows wide geographical divergence. The high incidence of stomach cancer in East Asia might be related to bacterial genotype. We used newly developed comparative methods to follow the evolution of East Asian H. pylori genomes using 20 complete genome sequences from Japanese, Korean, Amerind, European, and West African strains. Results A phylogenetic tree of concatenated well-defined core genes supported divergence of the East Asian lineage (hspEAsia; Japanese and Korean) from the European lineage ancestor, and then from the Amerind lineage ancestor. Phylogenetic profiling revealed a large difference in the repertoire of outer membrane proteins (including oipA, hopMN, babABC, sabAB and vacA-2) through gene loss, gain, and mutation. All known functions associated with molybdenum, a rare element essential to nearly all organisms that catalyzes two-electron-transfer oxidation-reduction reactions, appeared to be inactivated. Two pathways linking acetyl~CoA and acetate appeared intact in some Japanese strains. Phylogenetic analysis revealed greater divergence between the East Asian (hspEAsia) and the European (hpEurope) genomes in proteins in host interaction, specifically virulence factors (tip?), outer membrane proteins, and lipopolysaccharide synthesis (human Lewis antigen mimicry) enzymes. Divergence was also seen in proteins in electron transfer and translation fidelity (miaA, tilS), a DNA recombinase/exonuclease that recognizes genome identity (addA), and DNA/RNA hybrid nucleases (rnhAB). Positively selected amino acid changes between hspEAsia and hpEurope were mapped to products of cagA, vacA, homC (outer membrane protein), sotB (sugar transport), and a translation fidelity factor (miaA). Large divergence was seen in genes related to antibiotics: frxA (metronidazole resistance), def (peptide deformylase, drug target), and ftsA (actin-like, drug target). Conclusions These results demonstrate dramatic genome evolution within a species, especially in likely host interaction genes. The East Asian strains appear to differ greatly from the European strains in electron transfer and redox reactions. These findings also suggest a model of adaptive evolution through proteome diversification and selection through modulation of translational fidelity. The results define H. pylori East Asian lineages and provide essential information for understanding their pathogenesis and designing drugs and therapies that target them. PMID:21575176

  20. Taking Geoscience to Public Schools: Attitude and Knowledge Relationships

    NASA Astrophysics Data System (ADS)

    Silliman, J. E.; Hansen, A.; McDonald, J.; Martinez, M.

    2005-12-01

    The Cabeza de Vaca Earthmobile Program is an ongoing project that is designed to strengthen geoscience education in South Texas public schools. It began in June 2003 and is funded by the National Science Foundation. This outreach program involves collaboration between Texas A&M University-Corpus Christi and four independent school districts in South Texas with support from the South Texas Rural Systemic Initiative, another NSF-funded project. Additional curriculum support has been provided by various local and state organizations. Across Texas, fifth grade students are demonstrating a weakness in geoscience concepts as evidenced by their scores on the Texas Assessment of Knowledge and Skills. As a result, fifth and sixth grade public school students from low-income school districts were selected to participate in this program. At this age students are already making decisions that will affect their high school and college years. The main purpose of this project is to encourage these students, many of whom are Hispanic, to become geoscientists. This purpose is accomplished by enhancing their geoscience knowledge, nurturing their interest in geoscience and showing them what careers are available in the geosciences. Educators and scientists collaborate to engage students in scientific discovery through hands-on laboratory exercises and exposure to state-of-the-art technology (laptop computers, weather stations, telescopes, etc.). Students' family members become involved in the geoscience learning process as they participate in Family Science Night activities. Family Science Nights constitute an effective venue to reach the public. During the course of the Cabeza de Vaca Earthmobile Program, investigators have measured success in two ways: improvement in students' knowledge of geoscience concepts and change in students' attitudes towards geoscience. Findings include significant improvement in students' knowledge of geoscience. Students also report more positive attitudes toward geoscience after having participated in laboratory activities and Family Science Nights. Preliminary findings on the extent to which geoscience and geoscience careers become part of families' purviews, discourses and planning through involvement in Family Science Nights will be presented. Implications related to the success of this program, as indicated by measurement of students' knowledge and attitudes of geoscience as well as engagement of this program by families, will be discussed.

  1. Diagnóstico diferencial en la encefalitis por anticuerpos contra el receptor NMDA

    PubMed Central

    González-Valcárcel, J.; Rosenfeld, M.R.; Dalmau, J.

    2011-01-01

    Resumen Introducción La encefalitis por anticuerpos contra el receptor de NMDA (NMDAR) suele desarrollarse como un síndrome característico de evolución multifásica y diagnóstico diferencial amplio. Pacientes Presentamos a 2 pacientes diagnosticadas de encefalitis por anticuerpos NMDAR con un cuadro clínico típico, pero que inicialmente señaló otras etiologías. Discusión La afectación frecuente de pacientes jóvenes con manifestaciones psiquiátricas prominentes indica frecuentemente otras consideraciones diagnósticas; las más frecuentes son las encefalitis virales, los procesos psiquiátricos y el síndrome neuroléptico maligno. Varios síndromes previamente definidos de manera parcial o descriptiva en adultos y pacientes pediátricos probablemente eran casos de encefalitis anti-NMDAR. Conclusiones La encefalitis anti-NMDAR debe considerarse en pacientes jóvenes con manifestaciones psiquiátricas subagudas, movimientos anormales y alteraciones autonómicas. La caracterización clínica e inmunológica de esta enfermedad ha llevado a la identificación de nuevos anticuerpos que afectan a procesos de memoria, aprendizaje, conducta y psicosis. PMID:20964986

  2. Role of Helicobacter pylori in gastric cancer: advances and controversies.

    PubMed

    Meng, Wenbo; Bai, Bing; Sheng, Liang; Li, Yan; Yue, Ping; Li, Xun; Qiao, Liang

    2015-11-01

    Gastric cancer is one of the most common cancers of digestive system globally and Helicobacter pylori (HP) infection is believed to be a major risk factor. HP can be classified into different types based on the presence and expression level of CagA and VacA, and, when exposed to adverse environment, HP changes its phenotype from helical type to coccoid type, with each having different pathogenicity. The mechanisms of HP-induced gastric carcinogenesis and progression are complicated, including DNA nitration and oxidation induced by mutagenic factors, HP-induced epigenetic modifications, HP-induced disruption of the balance between cell proliferation and apoptosis, and HP-induced cancer cell invasion and metastasis. HP may also affect the biological function of cancer stem cells and induction of cell autophagy. The lipopolysaccharide produced by HP can act through toll-like receptor-4 (TLR-4) to induce gastric mucosal inflammation and is thereby linked to the development of gastric cancer. PMID:26645900

  3. Helicobacter pylori: correlation of the virulence marker iceA allele with clinical outcome in a high prevalence area.

    PubMed

    Yakoob, J; Abbas, Z; Khan, R; Salim, S A; Abrar, A; Awan, S; Ahmad, Z

    2015-01-01

    The association of Helicobacter pylori virulence marker 'induced by contact with epithelium A' (iceA) allele types was determined in H. pylori-related diseases and virulence markers. Gastric biopsies were obtained at EGD from patients for culture, histopathology and polymerase chain reaction (PCR) for iceA types, cagA and vacA alleles. Two hundred and eighty-four H. pylori isolates were examined. iceA type 1 was positive in 177 (62%) and iceA type 2 in 158 (56%). In iceA type 2, gastric ulcer was present in 34 (21%) (P < 0.001) and carcinoma in 28 (25%) (P = 0.002), compared to nine (8%) and 2 (2%) in iceA type 2-negative cases. For iceA type 2, 139 (88%) were associated with chronic active gastritis compared to 95 (75%) (P = 0.006) in iceA type 2-negative. H. pylori cagA was positive in 101 (64%) iceA type 2 strains compared to 57 (45%) in negative strains (P = 0.002). H. pylori iceA type 2 was dominant and associated with cagA, chronic active inflammation, gastric ulcer and carcinoma. PMID:26126322

  4. Identification of putative vaccine candidates against Helicobacter pylori exploiting exoproteome and secretome: a reverse vaccinology based approach.

    PubMed

    Naz, Anam; Awan, Faryal Mehwish; Obaid, Ayesha; Muhammad, Syed Aun; Paracha, Rehan Zafar; Ahmad, Jamil; Ali, Amjad

    2015-06-01

    Helicobacter pylori (H. pylori) is an important pathogen associated with diverse gastric disorders ranging from peptic ulcer to malignancy. It has also been recognized by the World Health Organization (WHO) as class I carcinogen. Conventional treatment regimens for H. pylori seem to be ineffective, possibly due to antibiotic resistance mechanisms acquired by the pathogen. In this study we have successfully employed a reverse vaccinology approach to predict the potential vaccine candidates against H. pylori. The predicted potential vaccine candidates include vacA, babA, sabA, fecA and omp16. Host-pathogen interactions analysis elaborated their direct or indirect role in the specific signaling pathways including epithelial cell polarity, metabolism, secretion system and transport. Furthermore, surface-exposed antigenic epitopes were predicted and analyzed for conservation among 39 complete genomes of H. pylori (Genbank) for all the candidate proteins. These epitopes may serve as a base for the development of broad spectrum peptide or multi-component vaccines against H. pylori. We also believe that the proposed pipeline can be extended to other pathogens and for the identification of novel candidates for the development of effective vaccines. PMID:25818402

  5. Salt glands in the Jurassic metriorhynchid Geosaurus: implications for the evolution of osmoregulation in Mesozoic marine crocodyliforms

    NASA Astrophysics Data System (ADS)

    Fernández, Marta; Gasparini, Zulma

    2008-01-01

    The presence of salt-excreting glands in extinct marine sauropsids has been long suspected based on skull morphology. Previously, we described for the first time the natural casts of salt-excreting glands in the head of the Jurassic metriorhynchid crocodyliform Geosaurus araucanensis from the Tithonian of the Vaca Muerta Formation in the Neuquén Basin (Argentina). In the present study, salt-excreting glands are identified in three new individuals (adult, a sub-adult and a juvenile) referable to the same species. New material provides significant information on the salt glands form and function and permit integration of evolutionary scenarios proposed on a physiological basis in extant taxa with evidence from the fossil record. G. araucanensis represents an advanced stage of the basic physiological model to marine adaptations in reptiles. G. araucanensis salt glands were hypertrophied. On this basis, it can be hypothesized that these glands had a high excretory capability. This stage implies that G. araucanensis (like extant pelagic reptiles, e.g. cheloniids) could have maintained constant plasma osmolality even when seawater or osmoconforming prey were ingested. A gradual model of marine adaptation in crocodyliforms based on physiology (freshwater to coastal/estuarine to estuarine /marine to pelagic life) is congruent with the phylogeny of crocodyliforms based on skeletal morphology. The fossil record suggests that the stage of marine pelagic adaptation was achieved by the Early Middle Jurassic. Salt gland size in the juvenile suggests that juveniles were, like adults, pelagic.

  6. Helicobacter pylori in gastric carcinogenesis

    PubMed Central

    Ahn, Hyo Jun; Lee, Dong Soo

    2015-01-01

    Gastric cancer still is a major concern as the third most common cancer worldwide, despite declining rates of incidence in many Western countries. Helicobacter pylori (H. pylori) is the major cause of gastric carcinogenesis, and its infection insults gastric mucosa leading to the occurrence of atrophic gastritis which progress to intestinal metaplasia, dysplasia, early gastric cancer, and advanced gastric cancer consequently. This review focuses on multiple factors including microbial virulence factors, host genetic factors, and environmental factors, which can heighten the chance of occurrence of gastric adenocarcinoma due to H. pylori infection. Bacterial virulence factors are key components in controlling the immune response associated with the induction of carcinogenesis, and cagA and vacA are the most well-known pathogenic factors. Host genetic polymorphisms contribute to regulating the inflammatory response to H. pylori and will become increasingly important with advancing techniques. Environmental factors such as high salt and smoking may also play a role in gastric carcinogenesis. It is important to understand the virulence factors, host genetic factors, and environmental factors interacting in the multistep process of gastric carcinogenesis. To conclude, prevention via H. pylori eradication and controlling environmental factors such as diet, smoking, and alcohol is an important strategy to avoid H. pylori-associated gastric carcinogenesis. PMID:26690981

  7. Signal transduction of Helicobacter pylori during interaction with host cell protein receptors of epithelial and immune cells

    PubMed Central

    Pachathundikandi, Suneesh Kumar; Tegtmeyer, Nicole; Backert, Steffen

    2013-01-01

    Helicobacter pylori infections can induce pathologies ranging from chronic gastritis, peptic ulceration to gastric cancer. Bacterial isolates harbor numerous well-known adhesins, vacuolating cytotoxin VacA, protease HtrA, urease, peptidoglycan, and type IV secretion systems (T4SS). It appears that H. pylori targets more than 40 known host protein receptors on epithelial or immune cells. A series of T4SS components such as CagL, CagI, CagY, and CagA can bind to the integrin ?5?1 receptor. Other targeted membrane-based receptors include the integrins ?v?3, ?v?5, and ?2 (CD18), RPTP-?/?, GP130, E-cadherin, fibronectin, laminin, CD46, CD74, ICAM1/LFA1, T-cell receptor, Toll-like receptors, and receptor tyrosine kinases EGFR, ErbB2, ErbB3, and c-Met. In addition, H. pylori is able to activate the intracellular receptors NOD1, NOD2, and NLRP3 with important roles in innate immunity. Here we review the interplay of various bacterial factors with host protein receptors. The contribution of these interactions to signal transduction and pathogenesis is discussed. PMID:24280762

  8. The functional interplay of Helicobacter pylori factors with gastric epithelial cells induces a multi-step process in pathogenesis

    PubMed Central

    2013-01-01

    Infections with the human pathogen Helicobacter pylori (H. pylori) can lead to severe gastric diseases ranging from chronic gastritis and ulceration to neoplastic changes in the stomach. Development and progress of H. pylori-associated disorders are determined by multifarious bacterial factors. Many of them interact directly with host cells or require specific receptors, while others enter the host cytoplasm to derail cellular functions. Several adhesins (e.g. BabA, SabA, AlpA/B, or OipA) establish close contact with the gastric epithelium as an important first step in persistent colonization. Soluble H. pylori factors (e.g. urease, VacA, or HtrA) have been suggested to alter cell survival and intercellular adhesions. Via a type IV secretion system (T4SS), H. pylori also translocates the effector cytotoxin-associated gene A (CagA) and peptidoglycan directly into the host cytoplasm, where cancer- and inflammation-associated signal transduction pathways can be deregulated. Through these manifold possibilities of interaction with host cells, H. pylori interferes with the complex signal transduction networks in its host and mediates a multi-step pathogenesis. PMID:24099599

  9. Pathogenesis of Helicobacter pylori Infection

    PubMed Central

    Kusters, Johannes G.; van Vliet, Arnoud H. M.; Kuipers, Ernst J.

    2006-01-01

    Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori. PMID:16847081

  10. Comparative genomic analysis of Helicobacter pylori from Malaysia identifies three distinct lineages suggestive of differential evolution

    PubMed Central

    Kumar, Narender; Mariappan, Vanitha; Baddam, Ramani; Lankapalli, Aditya K.; Shaik, Sabiha; Goh, Khean-Lee; Loke, Mun Fai; Perkins, Tim; Benghezal, Mohammed; Hasnain, Seyed E.; Vadivelu, Jamuna; Marshall, Barry J.; Ahmed, Niyaz

    2015-01-01

    The discordant prevalence of Helicobacter pylori and its related diseases, for a long time, fostered certain enigmatic situations observed in the countries of the southern world. Variation in H. pylori infection rates and disease outcomes among different populations in multi-ethnic Malaysia provides a unique opportunity to understand dynamics of host–pathogen interaction and genome evolution. In this study, we extensively analyzed and compared genomes of 27 Malaysian H. pylori isolates and identified three major phylogeographic lineages: hspEastAsia, hpEurope and hpSouthIndia. The analysis of the virulence genes within the core genome, however, revealed a comparable pathogenic potential of the strains. In addition, we identified four genes limited to strains of East-Asian lineage. Our analyses identified a few strain-specific genes encoding restriction modification systems and outlined 311 core genes possibly under differential evolutionary constraints, among the strains representing different ethnic groups. The cagA and vacA genes also showed variations in accordance with the host genetic background of the strains. Moreover, restriction modification genes were found to be significantly enriched in East-Asian strains. An understanding of these variations in the genome content would provide significant insights into various adaptive and host modulation strategies harnessed by H. pylori to effectively persist in a host-specific manner. PMID:25452339

  11. Growth phase-dependent composition of the Helicobacter pylori exoproteome.

    PubMed

    Snider, Christina A; Voss, Bradley J; McDonald, W Hayes; Cover, Timothy L

    2016-01-01

    Helicobacter pylori colonizes the human stomach and is associated with an increased risk of gastric cancer and peptic ulcer disease. Analysis of H. pylori protein secretion is complicated by the occurrence of bacterial autolysis. In this study, we analyzed the exoproteome of H. pylori at multiple phases of bacterial growth and identified 74 proteins that are selectively released into the extracellular space. These include proteins known to cause alterations in host cells, antigenic proteins, and additional proteins that have not yet been studied in any detail. The composition of the H. pylori exoproteome is dependent on the phase of bacterial growth. For example, the proportional abundance of the vacuolating toxin VacA in culture supernatant is higher during late growth phases than early growth phases, whereas the proportional abundance of many other proteins is higher during early growth phases. We detected marked variation in the subcellular localization of putative secreted proteins within soluble and membrane fractions derived from intact bacteria. By providing a comprehensive view of the H. pylori exoproteome, these results provide new insights into the array of secreted H. pylori proteins that may cause alterations in the gastric environment. PMID:26363098

  12. The antibacterial mode of action of allitridi for its potential use as a therapeutic agent against Helicobacter pylori infection.

    PubMed

    Liu, Shuang; Sun, Yundong; Li, Wenjuan; Yu, Han; Li, Xi; Liu, Zhifang; Zeng, Jiping; Zhou, Yabin; Chen, Chunyan; Jia, Jihui

    2010-02-01

    Eradication of Helicobacter pylori with traditional therapy often fails in clinical treatment. As a result, a novel efficacious therapeutic agent is strongly needed. Allitridi, a proprietary garlic derivative, has been successfully used to treat both systemic fungal and bacterial infections in China. Our previous study has shown a dose-dependent inhibitory effect of allitridi on H. pylori growth. However, the antibacterial mode of action of allitridi is still unclear. Proteomic analysis was used to study the global protein alterations induced by allitridi. A total of 21 protein spots were identified to be differentially expressed. Our results indicated that the bacteriostatic mechanism of allitridi in H. pylori can be attributed to its multitarget inhibitory effects in energy metabolism and biosynthesis including amino acid biosynthesis, protein synthesis, mRNA synthesis and fatty acid biosynthesis. Allitridi can also disturb the expression of antioxidant proteins and decrease the production of virulence factors. Western blot analysis showed that allitridi at subinhibitory concentrations can potently suppress the production of CagA and VacA. Our investigations on the antibacterial mode of action of allitridi provide an insight into the potential use of allitridi as a therapeutic agent against H. pylori infection. PMID:20030729

  13. Life histories and fitness of two tuber moth species feeding on native Andean potatoes.

    PubMed

    Horgan, F G; Quiring, D T; Lagnaoui, A; Pelletier, Y

    2012-08-01

    In the inter-Andean valleys of central Perú, two species of tuber moth, Phthorimaea operculella (Zeller) and Symmetrischema tangolias (Gyen), often occur simultaneously in stored potatoes. Traditional farming communities in the region produce a variety of native potatoes for local consumption. These include Solanum tuberosum subsp. andigena, the presumed predecessor of commercial potatoes, S. tuberosum subsp. tuberosum. In this study, we examined resistance against P. operculella in ten native Peruvian potato varieties (Casa blanca, Chispiadita, Madre de vaca, Mamaco negro, Misha, Chorisa, Mamaco rosado, Occa papa, Vacapa jayllo, and Yana tornasol). We also compared resistance in the first five of these varieties against S. tangolias. Varieties with pigmented periderms showed moderate resistance (30-40% against P. operculella in Mamaco negro, Mamaco rosado, and Yana tornasol and 55% against S. tangolias in Mamaco negro). All the other varieties were susceptible to both moth species. Small tubers tended to be the most resistant to the attack by both moths; however, this was not related to the availability of food for developing larvae, since pupal weight and development time were unaffected by the size of tubers. Similar responses by the two moths to native potatoes indicate that tuber resistance could be used to control the complex of tuber moths that damage potatoes in the Andes. We suggest that native potatoes, which are often easily introgressed with commercial potatoes, are a potential source of resistance against tuber moths. PMID:23950070

  14. Identification of cagA tyrosine phosphorylation DNA motifs in Helicobacter pylori isolates from peptic ulcer patients by novel PCR-restriction fragment length polymorphism and real-time fluorescence PCR assays.

    PubMed

    Owen, Robert J; Sharp, Sally I; Chisholm, Stephanie A; Rijpkema, Sjoerd

    2003-07-01

    Cag pathogenicity island-containing Helicobacter pylori (type I) induces signal transduction pathways resulting in tyrosine phosphorylation of proteins adjacent to the site of bacterial adhesion on host gastric epithelial cells. Conventional block PCR-restriction fragment length polymorphism (RFLP) and real-time LightCycler (LC) PCR hybridization assays, validated by direct sequencing, were designed to test for the presence of three nucleotide sequences corresponding to tyrosine phosphorylation motifs (TPMs) A, B, and C in 84 isolates of H. pylori type I from patients in England. Overall, the PCR assays demonstrated that one or more TPMs were present in 62 strains (75%). Motif A was common (71% of strains), whereas motifs B and C were rarer (8% of strains). Strains lacking a TPM were typically vacuolating cytotoxin genotype vacA m2. Motif A was widely distributed in relation to disease severity and was more commonly (but not significantly [P = 0.071]) associated with gastric ulcer than with duodenal ulcer (86 versus 56%). The LC hybridization assay provided a rapid means of detecting all three motifs, but RFLP analysis was more specific for TPM-A. TPMs provide novel additional strain markers for defining cagA variation, including identification of RFLP types within TPM-A. The presence of a particular TPM was not of direct diagnostic value, either singly or in combination, but the higher proportion of TPM-A strains in gastric ulcer patients merits further investigation. PMID:12843050

  15. Multiple Infection and Microdiversity among Helicobacter pylori Isolates in a Single Host in India

    PubMed Central

    Patra, Rajashree; Chattopadhyay, Santanu; De, Ronita; Ghosh, Prachetash; Ganguly, Mou; Chowdhury, Abhijit; Ramamurthy, T.; Nair, G. B.; Mukhopadhyay, Asish K.

    2012-01-01

    Helicobacter pylori is one of the most diverse bacterial species that chronically infects more than 70% of Indian population. Interestingly, data showing microdiversity of the H. pylori strains within a particular gastric niche remained scarce. To understand the extent of genetic diversity among H. pylori strains within a given host, 30 patients with gastro-duodenal problems were subjected to endoscopy and from each patient 10 single colonies were isolated. Characterization of each of these 10 single colonies by DNA fingerprinting as well as genotyping of several important genetic markers viz. cagA, vacA, iceA, vapD, cag PAI empty site, IS605, RFLP and two other genetic segments within cag PAI revealed that all of the 30 patients were infected with more than one strain and sometimes strains with 5 to 6 types of genetic variants. Analyses of certain genetic loci showed the microdiversity among the colonies from single patient, which may be due to the recombination events during long-term carriage of the pathogen. These results suggest that most of the patients have acquired H. pylori due to repeated exposure to this pathogen with different genetic make-up, which may increase the possibility of super infections. Genetic exchanges between these unrelated H. pylori strains may support certain H. pylori variant to grow better in a given host than the parental strain and thereby increasing the possibility for the severity of the infection. PMID:22952670

  16. Helicobacter pylori lipopolysaccharide hinders polymorphonuclear leucocyte apoptosis.

    PubMed

    Hofman, V; Ricci, V; Mograbi, B; Brest, P; Luciano, F; Boquet, P; Rossi, B; Auberger, P; Hofman, P

    2001-03-01

    A prominent histologic feature of Helicobacter pylori infection is a dense infiltration of polymorphonuclear leukocytes (PMNL) in gastric mucosa. H. pylori lipopolysaccharide (LPS) has been recognized as a primary virulence factor evoking acute mucosal inflammatory reaction. Previous works have shown that H. pylori LPS immunologic activities are lower than those of enterobacterial LPS. However, the effect of H. pylori LPS on spontaneous PMNL apoptosis, and mechanisms by which this H. pylori LPS may promote PMNL survival remain to be established. In this study, we investigated, by both morphologic and biochemical approaches, the action of H. pylori LPS on PMNL apoptosis in vitro, using broth culture filtrates (BCF) of H. pylori strains with different genotypes. We found that BCF from H. pylori caused a significant delay in spontaneous PMNL apoptosis and this delay was independent of the VacA, cag pathogenicity island and urease status. We demonstrated that LPS in BCF is responsible for this effect because it was abrogated by the LPS antagonist B287 (a synthetic analog of Rhodobactersphaeroides lipid A). Moreover, BCF from H. pylori induced P42/44MAP kinase activation in PMNL. Similar results were obtained with BCF of an Escherichia coli strain. Taken together these data suggest that longer survival of PMNL induced by H. pylori LPS may increase gastric epithelium injury in H. pylori-associated diseases. PMID:11310830

  17. Efficacy of the antimicrobial peptide TP4 against Helicobacter pylori infection: in vitro membrane perturbation via micellization and in vivo suppression of host immune responses in a mouse model

    PubMed Central

    Narayana, Jayaram Lakshmaiah; Huang, Han-Ning; Wu, Chang-Jer; Chen, Jyh-Yih

    2015-01-01

    Helicobacter pylori infection is marked by a strong association with various gastric diseases, including gastritis, ulcers, and gastric cancer. Antibiotic treatment regimens have low success rates due to the rapid occurrence of resistant H. pylori strains, necessitating the development of novel anti-H. pylori strategies. Here, we investigated the therapeutic potential of a novel peptide, Tilapia Piscidin 4 (TP4), against multidrug resistant gastric pathogen H. pylori, based on its in vitro and in vivo efficacy. TP4 inhibited the growth of both antibiotic-sensitive and -resistant H. pylori (CagA+, VacA+) via membrane micelle formation, which led to membrane depolarization and extravasation of cellular constituents. During colonization of gastric tissue, H. pylori infection maintains high T regulatorysubsets and a low Th17/Treg ratio, and results in expression of both pro- and anti-inflammatory cytokines. Treatment with TP4 suppressed Treg subset populations and pro- and anti-inflammatory cytokines. TP4 restored the Th17/Treg balance, which resulted in early clearance of H. pylori density and recovery of gastric morphology. Toxicity studies demonstrated that TP4 treatment has no adverse effects in mice or rabbits. The results of this study indicate that TP4 may be an effective and safe monotherapeutic agent for the treatment of multidrug resistant H. pylori infections. PMID:26002554

  18. Microevolution of Virulence-Related Genes in Helicobacter pylori Familial Infection

    PubMed Central

    Furuta, Yoshikazu; Konno, Mutsuko; Osaki, Takako; Yonezawa, Hideo; Ishige, Taichiro; Imai, Misaki; Shiwa, Yuh; Shibata-Hatta, Mari; Kanesaki, Yu; Yoshikawa, Hirofumi; Kamiya, Shigeru; Kobayashi, Ichizo

    2015-01-01

    Helicobacter pylori, a bacterial pathogen that can infect human stomach causing gastritis, ulcers and cancer, is known to have a high degree of genome/epigenome diversity as the result of mutation and recombination. The bacteria often infect in childhood and persist for the life of the host. One of the reasons of the rapid evolution of H. pylori is that it changes its genome drastically for adaptation to a new host. To investigate microevolution and adaptation of the H. pylori genome, we undertook whole genome sequencing of the same or very similar sequence type in multi-locus sequence typing (MLST) with seven genes in members of the same family consisting of parents and children in Japan. Detection of nucleotide substitutions revealed likely transmission pathways involving children. Nonsynonymous (amino acid changing) mutations were found in virulence-related genes (cag genes, vacA, hcpDX, tnf?, ggt, htrA and the collagenase gene), outer membrane protein (OMP) genes and other cell surface-related protein genes, signal transduction genes and restriction-modification genes. We reconstructed various pathways by which H. pylori can adapt to a new human host, and our results raised the possibility that the mutational changes in virulence-related genes have a role in adaptation to a child host. Changes in restriction-modification genes might remodel the methylome and transcriptome to help adaptation. This study has provided insights into H. pylori transmission and virulence and has implications for basic research as well as clinical practice. PMID:25978460

  19. The engineering and geological constraints of the intraslope basins and submarine canyons of the northwestern Gulf of Mexico

    SciTech Connect

    Bryant, W.R.; Yuh Liu, J.; Ponthier, J.

    1995-10-01

    It is well realized that future hydrocarbon discoveries on the upper and lower continental slope and rise off Texas and Louisiana necessitate innovative methods for the construction of platforms and pipelines in a very difficult engineering and complex geological environment. There are 105 intraslope basins and 5 major submarine canyons on the continental slope of the northwestern Gulf of Mexico, many of which may be prime targets for hydrocarbon production. Examination of the physiographic, geophysical and geotechnical characteristics of the intraslope basins of Pigmy and Vaca basins and the Alaminos submarine canyon are used as examples to typify the various engineering and geological constraints that are most likely to be encountered on the continental slope and rise and along the Sigsbee Escarpment in the northwestern Gulf of Mexico. High-resolution bathymetry identifies such constraints as high-angle intraslope basin walls, walls that exceed 40 degrees are not uncommon. Sediment slumps and other instabilities, such as long-term sediment creep and other affects of halokenesis and contemporaneous faulting, are illustrated and evaluated from high-resolution geophysics. The small canyons and large gullies that dissect the parameter flanks of Alaminos Canyon, that may be the results of both recent and old turbidity currents and debris flows, are structures that require engineering consideration in the implement of seafloor structures in, near or down slope of these features.

  20. Helicobacter pylori in gastric carcinogenesis.

    PubMed

    Ahn, Hyo Jun; Lee, Dong Soo

    2015-12-15

    Gastric cancer still is a major concern as the third most common cancer worldwide, despite declining rates of incidence in many Western countries. Helicobacter pylori (H. pylori) is the major cause of gastric carcinogenesis, and its infection insults gastric mucosa leading to the occurrence of atrophic gastritis which progress to intestinal metaplasia, dysplasia, early gastric cancer, and advanced gastric cancer consequently. This review focuses on multiple factors including microbial virulence factors, host genetic factors, and environmental factors, which can heighten the chance of occurrence of gastric adenocarcinoma due to H. pylori infection. Bacterial virulence factors are key components in controlling the immune response associated with the induction of carcinogenesis, and cagA and vacA are the most well-known pathogenic factors. Host genetic polymorphisms contribute to regulating the inflammatory response to H. pylori and will become increasingly important with advancing techniques. Environmental factors such as high salt and smoking may also play a role in gastric carcinogenesis. It is important to understand the virulence factors, host genetic factors, and environmental factors interacting in the multistep process of gastric carcinogenesis. To conclude, prevention via H. pylori eradication and controlling environmental factors such as diet, smoking, and alcohol is an important strategy to avoid H. pylori-associated gastric carcinogenesis. PMID:26690981

  1. An Update on Helicobacter pylori as the Cause of Gastric Cancer

    PubMed Central

    Zhang, Wei; Lu, Hong; Graham, David Y.

    2014-01-01

    Background Gastric cancer is the second most common cause of cancer deaths worldwide. The vast majority of gastric cancers are inflammation-related cancers caused by infection with Helicobacter pylori. H. pylori-induced oxidative stress damages DNA, resulting in genetic instability. In addition, H. pylori itself can cause DNA damage and epigenetic changes that trigger genetic instability and neoplastic transformation. Summary H. pylori strain-specific components act in combination with host factors and environmental and dietary factors to greatly enhance the inflammatory response and thus the cancer risk. Variations in several key factors, such as the cag pathogenicity island and the VacA protein, can trigger a greater inflammatory response in host cells. Genetic polymorphisms in the host such as in the IL-1? gene, and chromosomes 9p21.3 and 10q23 also play a contributing role. Finally, diet is a major external factor that modulates the risk of gastric cancer. Key Message The majority of gastric cancers are inflammation-related cancers caused by infection with H. pylori. Eradication of H. pylori is important for the prevention and treatment of gastric cancer. Practical Implications H. pylori eradication results in healing of gastritis and prevention of further H. pylori-induced genetic damage. Eradication of H. pylori prior to development of atrophic gastritis can prevent the development of gastric cancer. Japan has undertaken a nationwide program to identify and eliminate H. pylori, along with surveillance for those who underwent H. pylori eradication too late to eliminate cancer risk. Population-wide eradication of H. pylori will result in gastric cancer becoming a vanishingly rare disease. PMID:26672968

  2. Prospective study of Helicobacter pylori antigens and gastric noncardia cancer risk in the nutrition intervention trial cohort.

    PubMed

    Murphy, Gwen; Freedman, Neal D; Michel, Angelika; Fan, Jin-Hu; Taylor, Philip R; Pawlita, Michael; Qiao, You-Lin; Zhang, Han; Yu, Kai; Abnet, Christian C; Dawsey, Sanford M

    2015-10-15

    Helicobacter pylori (H. pylori) infection is the strongest known risk factor for gastric noncardia adenocarcinoma (GNCA). We used multiplex serology to determine whether seropositivity to 15 H. pylori proteins is associated with the subsequent development of noncardia gastric cancer in Linxian, China. We included 448 GNCA cases and 1242 controls from two time points within the Linxian General Population Nutrition Intervention Trial, Linxian. H. pylori multiplex seropositivity was defined as positivity to ?4 of the 15 included antigens. Odds ratios (ORs) and 95% confidence intervals (CIs) were adjusted for major GNCA risk factors. In addition, we undertook a meta-analysis combining H. pylori multiplex serology data from both time points. H. pylori multiplex seropositivity was associated with a significant increase in risk of GNCA at one time point (1985; OR: 3.44, 95% CI: 1.91, 6.19) and this association remained significant following adjustment for H. pylori or CagA ELISA seropositivity (OR: 2.92, 95% CI: 1.56, 5.47). Combining data from both time points in a meta-analysis H. pylori multiplex seropositivity was associated with an increased risk of GNCA, as were six individual antigens: GroEL, HP0305, CagA, VacA, HcpC and Omp. CagM was inversely associated with risk of GNCA. We identified six individual antigens that confer an increase in risk of GNCA within this population of high H. pylori seroprevalence, as well as a single antigen that may be inversely associated with GNCA risk. We further determined that the H. pylori multiplex assay provides additional information to the conventional ELISA methods on risk of GNCA. PMID:25845708

  3. Soluble Extracts from Helicobacter pylori Induce Dome Formation in Polarized Intestinal Epithelial Monolayers in a Laminin-Dependent Manner

    PubMed Central

    Terrés, A. M.; Windle, H. J.; Ardini, E.; Kelleher, D. P.

    2003-01-01

    Helicobacter pylori colonizes the stomach at the interface between the mucus layer and the apical pole of gastric epithelial cells. A number of secreted and shed products from the bacteria, such as proteins and lipopolysaccharide, are likely to have a role in the pathogenesis at the epithelial level. To determine the physiological response of transporting polarized epithelia to released soluble factors from the bacterium, we used the T84 cell line. Monolayers of T84 cells were exposed to soluble extracts from H. pylori. The extracts induced rapid “dome” formation as well as an immediate decrease in transepithelial electrical resistance. Domes are fluid-filled blister-like structures unique to polarized epithelia. Their formation has been linked to sodium-transporting events as well as to diminished adherence of the cells to the substrate. H. pylori-induced dome formation in T84 monolayers was exacerbated by amiloride and inhibited by ouabain. Furthermore, it was associated with changes in the expression of the laminin binding ?6?4 integrin and the 67-kDa laminin receptor. Domes formed primarily on laminin-coated filters, rather than on fibronectin or collagen matrices, and their formation was inhibited by preincubating the bacterial extract with soluble laminin. This effect was specific to H. pylori and independent of the urease, vacA, cagA, and Lewis phenotype of the strains. These data indicate that released elements from H. pylori can alter the physiological balance and integrity of the epithelium in the absence of an underlying immune response. PMID:12819097

  4. Comparative genomics and proteomics of Helicobacter mustelae, an ulcerogenic and carcinogenic gastric pathogen

    PubMed Central

    2010-01-01

    Background Helicobacter mustelae causes gastritis, ulcers and gastric cancer in ferrets and other mustelids. H. mustelae remains the only helicobacter other than H. pylori that causes gastric ulceration and cancer in its natural host. To improve understanding of H. mustelae pathogenesis, and the ulcerogenic and carcinogenic potential of helicobacters in general, we sequenced the H. mustelae genome, and identified 425 expressed proteins in the envelope and cytosolic proteome. Results The H. mustelae genome lacks orthologs of major H. pylori virulence factors including CagA, VacA, BabA, SabA and OipA. However, it encodes ten autotransporter surface proteins, seven of which were detected in the expressed proteome, and which, except for the Hsr protein, are of unknown function. There are 26 putative outer membrane proteins in H. mustelae, some of which are most similar to the Hof proteins of H. pylori. Although homologs of putative virulence determinants of H. pylori (NapA, plasminogen adhesin, collagenase) and Campylobacter jejuni (CiaB, Peb4a) are present in the H. mustelae genome, it also includes a distinct complement of virulence-related genes including a haemagglutinin/haemolysin protein, and a glycosyl transferase for producing blood group A/B on its lipopolysaccharide. The most highly expressed 264 proteins in the cytosolic proteome included many corresponding proteins from H. pylori, but the rank profile in H. mustelae was distinctive. Of 27 genes shown to be essential for H. pylori colonization of the gerbil, all but three had orthologs in H. mustelae, identifying a shared set of core proteins for gastric persistence. Conclusions The determination of the genome sequence and expressed proteome of the ulcerogenic species H mustelae provides a comparative model for H. pylori to investigate bacterial gastric carcinogenesis in mammals, and to suggest ways whereby cag minus H. pylori strains might cause ulceration and cancer. The genome sequence was deposited in EMBL/GenBank/DDBJ under accession number FN555004. PMID:20219135

  5. Classification of mafic clasts from mesosiderites: Implications for endogenous igneous processes

    SciTech Connect

    Rubin, A.E. ); Mittlefehldt, D.W. )

    1992-02-01

    The authors have analyzed thirteen igneous pebbles from the Vaca Muerta, EET87500, and Bondoc mesosiderites by electron microprobe and instrumental neutron activation and combined these data with literature data for forty-three analyzed mesosiderite clasts. They classify these well-characterized clasts into the following five principal groups: (1) Polygenic and monogenic cumulates (39%) are coarse-grained gabbros that are highly depleted in incompatible elements (relative to H chondrites); they formed at moderate depth either as residues of low-degree partial melting of pre-existing cumulate eucrites or as cumulates from parent melts similar to cumulate eucrites. (2) Polygenic basalts (30%) are finer-grained rocks with positive europium anomalies, La/Lu ratios < 1, and lower rare earth element abundances than basaltic eucrites. It seems likely that these rocks were formed near their parent body surface by remelting mixtures of major amounts of basaltic eucrites and lesser amounts of cumulate eucrites. (3) Quench-textured rocks comprise two compositional groups, (a) those which resemble basaltic eucrites (5%), and (b) those which resemble cumulate eucrites (2%). The quench-textured rocks are probably monogenic; they formed most likely when small-scale impacts at their parent body surface totally melted small amounts of basaltic or cumulate eucrite material. (4) Monogenic basalts (11%) resemble basaltic eucrites and formed by endogenous igneous processes on the mesosiderite parent body (MPB). (5) Ultramafic rocks are cumulates consisting mainly of large crystals of orthopyroxene (9%) or olivine (4%). Orthopyroxenite clasts closely resemble diogenites and were formed most likely by endogenous igneous processes.

  6. A Water Resources Management Model to Evaluate Climate Change Impacts in North-Patagonia, Argentina

    NASA Astrophysics Data System (ADS)

    Bucciarelli, L. F.; Losano, F. T.; Marizza, M.; Cello, P.; Forni, L.; Young, C. A.; Girardin, L. O.; Nadal, G.; Lallana, F.; Godoy, S.; Vallejos, R.

    2014-12-01

    Most recently developed climate scenarios indicate a potential future increase in water stress in the region of Comahue, located in the North-Patagonia, Argentina. This region covers about 140,000 km2 where the Limay River and the Neuquén River converge into the Negro River, constituting the largest integrated basins in Argentina providing various uses of water resources: a) hydropower generation, contributing 15% of the national electricity market; b) fruit-horticultural products for local markets and export; c) human and industrial water supply; d) mining and oil exploitation, including Vaca Muerta, second world largest reserves of shale gas and fourth world largest reserves of shale-oil. The span of multiple jurisdictions and the convergence of various uses of water resources are a challenge for integrated understanding of economically and politically driven resource use activities on the natural system. The impacts of climate change on the system could lead to water resource conflicts between the different political actors and stakeholders. This paper presents the results of a hydrological simulation of the Limay river and Neuquén river basins using WEAP (Water Evaluation and Planning) considering the operation of artificial reservoirs located downstream at a monthly time step. This study aims to support policy makers via integrated tools for water-energy planning under climate uncertainties, and to facilitate the formulation of water policy-related actions for future water stress adaptation. The value of the integrated resource use model is that it can support local policy makers understand the implications of resource use trade-offs under a changing climate: 1) water availability to meet future growing demand for irrigated areas; 2) water supply for hydropower production; 3) increasing demand of water for mining and extraction of unconventional oil; 4) potential resource use conflicts and impacts on vulnerable populations.

  7. Analysis of Surface-Exposed Outer Membrane Proteins in Helicobacter pylori

    PubMed Central

    Voss, Bradley J.; Gaddy, Jennifer A.; McDonald, W. Hayes

    2014-01-01

    More than 50 Helicobacter pylori genes are predicted to encode outer membrane proteins (OMPs), but there has been relatively little experimental investigation of the H. pylori cell surface proteome. In this study, we used selective biotinylation to label proteins localized to the surface of H. pylori, along with differential detergent extraction procedures to isolate proteins localized to the outer membrane. Proteins that met multiple criteria for surface-exposed outer membrane localization included known adhesins, as well as Cag proteins required for activity of the cag type IV secretion system, putative lipoproteins, and other proteins not previously recognized as cell surface components. We identified sites of nontryptic cleavage consistent with signal sequence cleavage, as well as C-terminal motifs that may be important for protein localization. A subset of surface-exposed proteins were highly susceptible to proteolysis when intact bacteria were treated with proteinase K. Most Hop and Hom OMPs were susceptible to proteolysis, whereas Hor and Hof proteins were relatively resistant. Most of the protease-susceptible OMPs contain a large protease-susceptible extracellular domain exported beyond the outer membrane and a protease-resistant domain at the C terminus with a predicted ?-barrel structure. These features suggest that, similar to the secretion of the VacA passenger domain, the N-terminal domains of protease-susceptible OMPs are exported through an autotransporter pathway. Collectively, these results provide new insights into the repertoire of surface-exposed H. pylori proteins that may mediate bacterium-host interactions, as well as the cell surface topology of these proteins. PMID:24769695

  8. Helicobacter pylori-Induced Histone Modification, Associated Gene Expression in Gastric Epithelial Cells, and Its Implication in Pathogenesis

    PubMed Central

    Ding, Song-Ze; Fischer, Wolfgang; Kaparakis-Liaskos, Maria; Liechti, George; Merrell, D. Scott; Grant, Patrick A.; Ferrero, Richard L.; Crowe, Sheila E.; Haas, Rainer; Hatakeyama, Masanori; Goldberg, Joanna B.

    2010-01-01

    Histone modifications are critical in regulating gene expression, cell cycle, cell proliferation, and development. Relatively few studies have investigated whether Helicobacter pylori, the major cause of human gastric diseases, affects histone modification. We therefore investigated the effects of H. pylori infection on histone modifications in a global and promoter-specific manner in gastric epithelial cells. Infection of gastric epithelial cells by wild-type H. pylori induced time- and dose-dependent dephosphorylation of histone H3 at serine 10 (H3 Ser10) and decreased acetylation of H3 lysine 23, but had no effects on seven other specific modifications. Different cag pathogenicity island (PAI)-containing-clinical isolates showed similar abilities to induce H3 Ser10 dephosphorylation. Mutation of cagA, vacA, nonphosphorylateable CagA mutant cagAEPISA, or disruption of the flagella showed no effects, while deletion of the entire cagPAI restored the H3 Ser10 phosphorylation to control levels. Analysis of 27 cagPAI mutants indicated that the genes that caused H3 Ser10 dephosphorylation were similar to those that were previously found to induce interleukin-8, irrespective of CagA translocation. This effect was independent of ERK or p38 pathways and type I interferon signaling. Additionally, c-Jun and hsp70 gene expression was associated with this histone modification. These results demonstrate that H. pylori alters histone modification and host response via a cagA-, vacA-independent, but cagPAI-dependent mechanisms, which contribute to its persistent infection and pathogenesis. PMID:20368982

  9. Virulence genes of Helicobacter pylori in the Dominican Republic

    PubMed Central

    Shiota, Seiji; Cruz, Modesto; Abreu, José A. Jiménez; Mitsui, Takahiro; Terao, Hideo; Disla, Mildre; Iwatani, Shun; Nagashima, Hiroyuki; Matsuda, Miyuki; Uchida, Tomohisa; Tronilo, Lourdes; Rodríguez, Eduardo

    2014-01-01

    Although the incidence of gastric cancer in the Dominican Republic is not high, the disease remains a significant health problem. We first conducted a detailed analysis of Helicobacter pylori status in the Dominican Republic. In total, 158 patients (103 females and 55 males; mean age 47.1±16.2 years) were recruited. The status of H. pylori infection was determined based on four tests: rapid urease test, culture test, histological test and immunohistochemistry. The status of cagA and vacA genotypes in H. pylori was examined using PCR and gene sequencing. The overall prevalence of H. pylori infection was 58.9?%. No relationship was found between the H. pylori infection rate and the age range of 17–91 years. Even in the youngest group (patients aged <29 years), the H. pylori infection rate was 62.5?%. Peptic ulcer was found in 23 patients and gastric cancer was found in one patient. The H. pylori infection rate in patients with peptic ulcer was significantly higher than that in patients with gastritis (82.6 versus 54.5?%, P<0.01). The cagA-positive/vacA s1m1 genotype was the most prevalent (43/64, 67.2?%). Compared with H. pylori-negative patients, H. pylori-positive patients showed more severe gastritis. Furthermore, the presence of cagA was related to the presence of more severe gastritis. All CagA-positive strains had Western-type CagA. In conclusion, we found that H. pylori infection is a risk factor for peptic ulcer in the Dominican Republic. Patients with cagA-positive H. pylori could be at higher risk for severe inflammation and atrophy. PMID:24965801

  10. Helicobacter pylori in Iran: A systematic review on the association of genotypes and gastroduodenal diseases

    PubMed Central

    Hosseini, Elham; Poursina, Farkhondeh; de Wiele, Tom Van; Safaei, Hajieh Ghasemian; Adibi, Peyman

    2012-01-01

    Background: Helicobacter pylori (H. pylori) infection is known as a major etiologic factor for a variety of gastroduodenal diseases. In Iran, with a high rate of H. pylori infection close to 90%, numerous studies have revealed many aspects of interaction between the bacterium, mucosal surface and induction of disease outcome. The organism is genetically diverse and several virulence factors are attributed to the more virulent strains. The well-characterized virulence factors of H. pylori are cytotoxin associated gene A and vacuolating cytotoxin gene A. The distribution pattern of H. pylori genotypes and its association with disease status varies geographically. The present review focused on the virulence factors and genotyping of H. pylori in relation to gastroduodenal disorders in different regions of Iran. Methods: In total, 398 studies were reported on different aspects related to H. pylori in our electronic search from 1995-2011. H. pylori infection and its virulence factors in association with disease status were investigated in 159 reports. Looking specifically at the gastrointestinal tract disorders, the most relevant reports including 37 papers were selected. Results: We found no correlation of cagA genotype and disease status in the majority of studies, whereas vacA was demonstrated as a useful marker in predicting the disease outcome. The results of reports on other virulence factors of H. pylori such as blood group antigen-binding adhesion gene A, the induced by contact with epithelium gene A, the outer inflammatory protein A, the duodenal ulcer promoting gene A, and Helicobacter outer membrane gene and their relation with disease status were contradictory. Conclusions: Although different markers of H. pylori were emphasized as useful when predicting disease outcomes in some studies, the inconsistent researches and the scarcity of data made any conclusion or even comparison impossible. Considering the gap of information observed during our search relating to genotyping and other aspects of H. pylori infection, further investigations are suggested. PMID:23267382

  11. Comparative Genomics of a Helicobacter pylori Isolate from a Chinese Yunnan Naxi Ethnic Aborigine Suggests High Genetic Divergence and Phage Insertion

    PubMed Central

    You, Yuanhai; He, Lihua; Zhang, Maojun; Zhang, Jianzhong

    2015-01-01

    Helicobacter pylori is a common pathogen correlated with several severe digestive diseases. It has been reported that isolates associated with different geographic areas, different diseases and different individuals might have variable genomic features. Here, we describe draft genomic sequences of H. pylori strains YN4-84 and YN1-91 isolated from patients with gastritis from the Naxi and Han populations of Yunnan, China, respectively. The draft sequences were compared to 45 other publically available genomes, and a total of 1059 core genes were identified. Genes involved in restriction modification systems, type four secretion system three (TFS3) and type four secretion system four (TFS4), were identified as highly divergent. Both YN4-84 and YN1-91 harbor intact cag pathogenicity island (cagPAI) and have EPIYA-A/B/D type at the carboxyl terminal of cagA. The vacA gene type is s1m2i1. Another major finding was a 32.5-kb prophage integrated in the YN4-84 genome. The prophage shares most of its genes (30/33) with Helicobacter pylori prophage KHP30. Moreover, a 1,886 bp transposable sequence (IS605) was found in the prophage. Our results imply that the Naxi ethnic minority isolate YN4-84 and Han isolate YN1-91 belong to the hspEAsia subgroup and have diverse genome structure. The genome has been extensively modified in several regions involved in horizontal DNA transfer. The important roles played by phages in the ecology and microevolution of H. pylori were further emphasized. The current data will provide valuable information regarding the H. pylori genome based on historic human migrations and population structure. PMID:25799515

  12. Review: prospects for the use of extracts and polysaccharides from marine algae to prevent and treat the diseases caused by Helicobacter pylori.

    PubMed

    Besednova, Natalya N; Zaporozhets, Tatyana S; Somova, Larisa M; Kuznetsova, Tatyana A

    2015-04-01

    Helicobacter pylori possesses a broad spectrum of pathogenic factors that allow it to survive and colonize the gastric mucosa, and thus, the pathogenetic targets, which have the same diversity, require search for and the development of alternative, effective, and innocuous means for the eradication of H. pylori. In recent years, fucoidans have been extensively studied due to the numerous interesting biological activities, including the anti-adhesive, anti-oxidative, antitoxic, immunomodulatory, anticoagulant, and anti-infection effects. This review summarizes the data on the effects of extracts and sulfated polysaccharides of marine algae, mainly fucoidans, on pathogenic targets in Helicobacter infection. The pathogenetic targets for therapeutic agents after H. pylori infection, such as flagellas, urease, and other enzymes, including adhesins, cytotoxin A (VacA), phospholipase, and L-8, are characterized here. The main target for the sulfated polysaccharides of seaweed is cell receptors of the gastric mucosa. This review presents the published data about the pleiotropic anti-inflammatory effects of polysaccharides on the gastric mucosa. It is known that fucoidan and other sulfated polysaccharides from algae have anti-ulcer effects, prevent the adhesion of H. pylori to, and reduce the formation of biofilm. The authors speculate that the effect of sulfated polysaccharides on the infectious process caused by H. pylori is related to their action on innate and adaptive immunity cells, and also anti-oxidant and antitoxic potential. Presented in the review are materials indicated for the study of extracts and sulfated polysaccharides from seaweed during H. pylori infection, as these compounds are characterized by multimodality actions. Based on the analysis of literary materials in recent years, the authors concluded that fucoidan can be attributed to the generation of new candidates to create drugs intended for the inclusion in the scheme of eradication therapy of H. pylori infection. PMID:25660579

  13. Long-term periodic anthelmintic treatments are associated with increased allergen skin reactivity

    PubMed Central

    Endara, P; Vaca, M; Chico, M E; Erazo, S; Oviedo, G; Quinzo, I; Rodriguez, A; Lovato, R; Moncayo, A-L; Barreto, M L; Rodrigues, L C; Cooper, P J

    2010-01-01

    Background The low prevalence of allergic disease in the rural tropics has been attributed to the protective effects of chronic helminth infections. There is concern that treatment-based control programmes for these parasites may lead to an increase in the prevalence of allergic diseases. Objective We measured the impact of 15–17 years of anthelmintic treatment with ivermectin on the prevalence of allergen skin test reactivity and allergic symptoms in school-age children. Methods The prevalence of allergen skin test reactivity, exercise-induced bronchospasm and allergic symptoms was compared between school-age children living in communities that had received community-based treatments with ivermectin (for onchocerciasis control) for a period of 15–17 years with those living in geographically adjacent communities that had received no ivermectin. Results The prevalence of allergen skin test reactivity was double in children living in treated communities compared with those in untreated communities (16.7% vs. 8.7%, adjusted OR 2.10, 95% CI 1.50–2.94, P<0.0001), and the effect was mediated partly by a reduced prevalence of Trichuris trichiura among treated children. Ivermectin treatments were associated with an increased prevalence of recent eczema symptoms (adjusted OR 2.24, 95% CI 1.05–4.78, P=0.04) but not symptoms of asthma or rhino-conjunctivitis. The effect on eczema symptoms was not associated with reductions in geohelminth infections. Conclusion Long-term periodic treatments with ivermectin were associated with an increased prevalence of allergen skin test reactivity. There was some evidence that treatment was associated with an increased prevalence of recent eczema symptoms but not those of asthma or rhino-conjunctivitis. Cite this as: P. Endara, M. Vaca, M. E. Chico, S. Erazo, G. Oviedo, I. Quinzo, A. Rodriguez R. Lovato, A.-L. Moncayo, M. L. Barreto, L. C. Rodrigues and P. J. Cooper, Clinical & Experimental Allergy, 2010 (40) 1669–1677. PMID:21039971

  14. The microbiological, histological, immunological and molecular determinants of Helicobacter pylori infection in guinea pigs as a convenient animal model to study pathogenicity of these bacteria and the infection dependent immune response of the host.

    PubMed

    Walencka, Maria; Gonciarz, Weronika; Mnich, Eliza; Gajewski, Adrian; Stawerski, Pawel; Knapik-Dabrowicz, Alina; Chmiela, Magdalena

    2015-01-01

    Helicobacter pylori is an etiological agent of chronic gastritis, gastric and duodenal ulcers and gastric cancers. The use of an appropriate animal model for experimental studies on the pathogenesis of H. pylori infections is necessary due to the chronic character of such infections and difficulties in identifying their early stage in humans. The aim of this study was to develop a guinea pig model of H. pylori infection and identify its microbiological, histological, serological and molecular determinants. Guinea pigs were inoculated per os with H. pylori strains: CCUG 17874 or ATCC 700312, both producing vacuolating cytotoxin A (VacA) and cytotoxin associated gene A (CagA) protein, suspended in Brucella broth with fetal calf serum (FCS) and Skirrow supplement of antibiotics. To determine H. pylori colonization, 7 and 28 days after the challenge, a panel of diagnostic methods was used. It included culturing of microorganisms from the gastric tissue, histopathological analysis of gastric sections, stained by Mayer,s haematoxylin and eosin to assess inflammatory response, by Giemsa as well as Warthin-Starry silver staining to visualise Helicobacter-like organisms (HLO) and with anti-Ki-67 antigen to assess epithelial cell proliferation. H. pylori infection was also confirmed by polymerase chain reactions (PCR) for detection in gastric tissue of ureC and cagA genes and by serological assessment of H. pylori antigens in faeces. This study showed the usefulness of microbiological, histological, immunological and molecular methods for the detection of persistent H. pylori infections in guinea pigs, which could be an appropriate model for studying H. pylori pathogenesis and the related immune response against these microbes. PMID:26610308

  15. Electron Microscopic, Genetic and Protein Expression Analyses of Helicobacter acinonychis Strains from a Bengal Tiger

    PubMed Central

    Tegtmeyer, Nicole; Rivas Traverso, Francisco; Rohde, Manfred; Oyarzabal, Omar A.; Lehn, Norbert; Schneider-Brachert, Wulf; Ferrero, Richard L.; Fox, James G.; Berg, Douglas E.; Backert, Steffen

    2013-01-01

    Colonization by Helicobacter species is commonly noted in many mammals. These infections often remain unrecognized, but can cause severe health complications or more subtle host immune perturbations. The aim of this study was to isolate and characterize putative novel Helicobacter spp. from Bengal tigers in Thailand. Morphological investigation (Gram-staining and electron microscopy) and genetic studies (16SrRNA, 23SrRNA, flagellin, urease and prophage gene analyses, RAPD DNA fingerprinting and restriction fragment polymorphisms) as well as Western blotting were used to characterize the isolated Helicobacters. Electron microscopy revealed spiral-shaped bacteria, which varied in length (2.5–6 µm) and contained up to four monopolar sheathed flagella. The 16SrRNA, 23SrRNA, sequencing and protein expression analyses identified novel H. acinonychis isolates closely related to H. pylori. These Asian isolates are genetically very similar to H. acinonychis strains of other big cats (cheetahs, lions, lion-tiger hybrid and other tigers) from North America and Europe, which is remarkable in the context of the great genetic diversity among worldwide H. pylori strains. We also found by immunoblotting that the Bengal tiger isolates express UreaseA/B, flagellin, BabA adhesin, neutrophil-activating protein NapA, HtrA protease, ?-glutamyl-transpeptidase GGT, Slt lytic transglycosylase and two DNA transfer relaxase orthologs that were known from H. pylori, but not the cag pathogenicity island, nor CagA, VacA, SabA, DupA or OipA proteins. These results give fresh insights into H. acinonychis genetics and the expression of potential pathogenicity-associated factors and their possible pathophysiological relevance in related gastric infections. PMID:23940723

  16. Helicobacter pylori in Vegetables and Salads: Genotyping and Antimicrobial Resistance Properties

    PubMed Central

    Yahaghi, Emad; Khamesipour, Faham; Mashayekhi, Fatemeh; Safarpoor Dehkordi, Farhad; Sakhaei, Mohammad Hossein; Masoudimanesh, Mojtaba; Khameneie, Maryam Khayyat

    2014-01-01

    From a clinical and epidemiological perspective, it is important to know which genotypes and antibiotic resistance patterns are present in H. pylori strains isolated from salads and vegetables. Therefore, the present investigation was carried out to find this purpose. Three hundred eighty washed and unwashed vegetable samples and fifty commercial and traditional salad samples were collected from Isfahan, Iran. Samples were cultured and those found positive for H. pylori were analyzed using PCR. Antimicrobial susceptibility testing was performed using disk diffusion method. Seven out of 50 (14%) salad and 52 out of 380 (13.68%) vegetable samples harbored H. pylori. In addition, leek, lettuce, and cabbage were the most commonly contaminated samples (30%). The most prevalent virulence genes were oipA (86.44%) and cagA (57.625). VacA s1a (37.28%) and iceA1 (47.45%) were the most prevalent genotypes. Forty different genotypic combinations were recognized. S1a/cagA+/iceA1/oipA+ (33.89%), s1a/cagA+/iceA2/oipA (30.50%), and m1a/cagA+/iceA1/oipA+ (28.81%) were the most prevalent combined genotypes. Bacterial strains had the highest levels of resistance against metronidazole (77.96%), amoxicillin (67.79%), and ampicillin (61.01%). High similarity in the genotyping pattern of H. pylori among vegetable and salad samples and human specimens suggests that vegetable and salads may be the sources of the bacteria. PMID:25184146

  17. Microbial Disruption of Autophagy Alters Expression of the RISC Component AGO2, a Critical Regulator of the miRNA Silencing Pathway

    PubMed Central

    Sibony, Michal; Abdullah, Majd; Greenfield, Laura; Raju, Deepa; Wu, Ted; Rodrigues, David M.; Galindo-Mata, Esther; Mascarenhas, Heidi; Philpott, Dana J.; Silverberg, Mark S.

    2015-01-01

    Background: Autophagy is implicated in Crohn's disease (CD) pathogenesis. Recent evidence suggests autophagy regulates the microRNA (miRNA)-induced silencing complex (miRISC). Therefore, autophagy may play a novel role in CD by regulating expression of miRISC, thereby altering miRNA silencing. As microbes associated with CD can alter autophagy, we hypothesized that microbial disruption of autophagy affects the critical miRISC component AGO2. Methods: AGO2 expression was assessed in epithelial and immune cells, and intestinal organoids with disrupted autophagy. Microarray technology was used to determine the expression of downstream miRNAs in cells with defective autophagy. Results: Increased AGO2 was detected in autophagy-deficient ATG5?/? and ATG16?/? mouse embryonic fibroblast cells (MEFs) in comparison with wild-type MEFs. Chemical agents and VacA toxin, which disrupt autophagy, increased AGO2 expression in MEFs, epithelial cells lines, and human monocytes, respectively. Increased AGO2 was also detected in ATG7?/? intestinal organoids, in comparison with wild-type organoids. Five miRNAs were differentially expressed in autophagy-deficient MEFs. Pathway enrichment analysis of the differentially expressed miRNAs implicated signaling pathways previously associated with CD. Conclusions: Taken together, our results suggest that autophagy is involved in the regulation of the critical miRISC component AGO2 in epithelial and immune cells and primary intestinal epithelial cells. We propose a mechanism by which autophagy alters miRNA expression, which likely impacts the regulation of CD-associated pathways. Furthermore, as enteric microbial products can manipulate autophagy and AGO2, our findings suggest a novel mechanism by which enteric microbes could influence miRNA to promote disease. PMID:26332312

  18. Mucosal interleukin-21 mRNA expression level is high in patients with Helicobacter pylori and is associated with the severity of gastritis

    PubMed Central

    Bagheri, Nader; Azadegan-Dehkordi, Fatemeh; Zamanzad, Benham; Rahimian, Ghorbanali; Taghikhani, Afshin; Rafieian-Kopaei, Mahmoud; Shirzad, Hedayatollah

    2015-01-01

    Helicobacter pylori (H. pylori) infection is associated with gastritis and marked infiltration of the gastric mucosa by several cytokines secreting inflammatory cells. Different clinical forms of the infection may reflect distinctive patterns of cytokine expression. Interleukin (IL)-17, IL-21, IL-22, and IL-23 have been reported to be involved in H. pylori-induced gastric mucosal inflammation, but the details and relationship to different patterns of inflammation and virulence factors remain unclear. The present study was launched to analyse IL-6 expression in H. pylori-infected and uninfected gastric patients and to investigate its correlation with chronic gastritis among H. pylori-infected patients. Total RNA was extracted from the gastric antrum biopsies of 48 H. pylori-infected patients and 38 H. pylori uninfected patients. Mucosal IL-21 mRNA expression level in H. pylori-infected and uninfected gastric biopsy was determined by real-time PCR. The presence of vacA (vacuolating cytotoxin A) and cagA (cytotoxin associated gene A) virulence factors were evaluated using PCR. Interleukin-21 mRNA expression was significantly high in biopsies of H. pylori-infected patients compared to H. pylori uninfected patients, and the mucosal IL-21 mRNA level was positively correlated with the grade of chronic inflammation. There was no association between virulence factors and IL-21 mRNA expression. We believe that IL-21 might be involved in the pathogenesis of H. pylori and might be an index of the severity of chronic gastritis. PMID:26155185

  19. MTHFR C677T polymorphism and differential methylation status in gastric cancer: an association with Helicobacter pylori infection.

    PubMed

    Neves Filho, Eduardo Henrique Cunha; Alves, Markenia Kelia Santos; Lima, Valeska Portela; Rabenhorst, Silvia Helena Barem

    2010-12-01

    MTHFR C677T and Helicobacter pylori infection are believed to play critical roles in the DNA methylation process, an epigenetic feature frequently found in gastric cancer. The aim of this study was to verify the associations between the MTHFR C677T polymorphism and the methylation status of three gastric cancer-related genes. The influence of H. pylori strains was also assessed. DNA extracted from 71 gastric tumor samples was available for MTHFR C677T genotyping by PCR-RFLP, promoter methylation identification by MS-PCR and H. pylori detection and posterior subtyping (cagA and vacA genes) by PCR. In the distal tumors, a positive correlation was found between the methylation of CDKN2A and the allele T carriers (r=0.357; p=0.009). Considering the eldest patients (age ?60 years old), this correlation was even higher (r=0,417; p=0.014). H. pylori infection by highly pathogenic strains (cagA+/vacAs1m1) was also found correlated to promoter methylation of CDKN2A and the allele T carriers in distal tumors (r=0.484; p=0.026). No significant correlation was verified between MTHFR C677T genotype and promoter methylation status when we analyzed the general sample. DNA methylation in CDKN2A associated to the MTHFR 677T carrier is suggested to be a distal tumor characteristic, especially in those 60 years old or older, and it seems to depend on the infection by H. pylori cagA/vacAs1m1 strains. PMID:20957490

  20. Inter- and intra-plate deformation at North American plate boundaries

    NASA Technical Reports Server (NTRS)

    Beavan, John; Gilbert, Lewis E.; Scholz, Chris

    1992-01-01

    A geodetic network which spans the region between San Francisco and Lake Tahoe has been measured 5 times completely with triangulation in 1880, 1922, 1929, 1943, 1963. A resurvey with the Global Positioning System (GPS) in 1991 allows the formation of 1 coseismic and 4 interseismic epochs. The data from this network provide a unique opportunity to examine the temporal and spatial evolution of the strain field associated with the 1906 San Francisco earthquake in particular and with the Pacific-North American plate boundary in general. Calculations of strain rate from the network data lead to the following conclusions. (1) There is no resolvable (greater than 0.05 microradians/yr) strain in between Sutter Buttes and the Sierra Nevada. (2) Throughout the time since the 1906 earthquake, a region extending at least as far east as the westernmost Great Valley has been undergoing deformation related to Pac:Nam interaction and the associated earthquake cycle. (3) In the time and space of overlap, our results agree with those from the United States Geological Survey (USGS) trilateration data. Both data sets indicate that strain must be accumulating to the east of Vaca. (4) The San Andreas discrepancy cannot be accommodated in the Great Valley at the 1 sigma level of our results. It is possible to absorb it in that region at the 2 sigma level. (5) Strain rate is elevated in the years following the earthquake and decays slowly with time. It is possible that the rate in the Coast Ranges increases until around 1950 and then decays. With the exception of one epoch, strain rate in the Coast Ranges is consistently fault parallel, shows no sign changes, and is consistent with monotonic strain accumulation.

  1. Multiplex H. pylori Serology and Risk of Gastric Cardia and Noncardia Adenocarcinomas.

    PubMed

    Shakeri, Ramin; Malekzadeh, Reza; Nasrollahzadeh, Dariush; Pawilta, Michael; Murphy, Gwen; Islami, Farhad; Sotoudeh, Masoud; Michel, Angelika; Etemadi, Arash; Waterboer, Tim; Poustchi, Hossein; Brennan, Paul; Boffetta, Paolo; Dawsey, Sanford M; Kamangar, Farin; Abnet, Christian C

    2015-11-15

    The reported associations with gastric adenocarcinoma and seropositivity to different Helicobacter pylori antigens using multiplex serology have not been consistent across studies. We aimed to investigate the association between 15 different multiplex serology antigens and the risk of gastric cardia (GCA) and gastric noncardia (GNCA) adenocarcinomas in northeastern Iran, a population with high rates of gastric adenocarcinoma. We included 272 cases of gastric adenocarcinoma (142 GCA, 103 GNCA, and 27 unspecified) and 524 controls who were individually matched to cases for age, sex, and place of residence in a population-based case-control study. Seropositivity to H. pylori was assessed using both multiplex serology and H. pylori IgG ELISA. Ninety-five percent of controls were seropositive to H. pylori. Of the 15 antibodies in the multiplex assay, 11 showed no significant association with gastric adenocarcinomas. CagA and VacA were associated with a significantly increased risk of all gastric adenocarcinoma and GNCA in multivariate models. Surprisingly, GroEL and NapA were significantly associated with a reduced risk of these tumors. Only CagA antigen was associated with significantly elevated risk of GCA. We found no associations between H. pylori seropositivity overall either by whole-cell ELISA test or multiplex serology, likely due to the high prevalence of seropositivity. Individual antigen testing showed that CagA positivity was associated with increased risk of both noncardia and cardia adenocarcinoma, which is similar to some other Asian populations, whereas two antigens were associated with lower risk of gastric cancer. This latter result was unexpected and should be retested in other populations. Cancer Res; 75(22); 4876-83. ©2015 AACR. PMID:26383162

  2. Recombinant human lactoferrin enhances the efficacy of triple therapy in mice infected with Helicobacter pylori

    PubMed Central

    YUAN, YUPING; WU, QINYI; CHENG, GUOXIANG; LIU, XUEFANG; LIU, SIGUO; LUO, JUAN; ZHANG, AIMIN; BIAN, LI; CHEN, JIANQUAN; LV, JIAJUN; DONG, XIANGQIAN; YANG, GANG; ZHU, YUNZHEN; MA, LANQING

    2015-01-01

    Helicobacter pylori (H. pylori) is a life-threatening pathogen which causes chronic gastritis, gastric ulcers and even stomach cancer. Treatment normally involves bacterial eradication; however, this type of treatment only has a rate of effectiveness of <80%. Thus, it is a matter of some urgency to develop new therapeutic strategies. Lactoferrin, a member of the transferrin family of iron-binding proteins, has been proven to be effective in removing a vast range of pathogens, including H. pylori. In the present study, we examined the effectiveness of recombinant human lactoferrin (rhLf) isolated from transgenic goats as a treatment for H. pylori in vitro and in vivo. For the in vivo experiments, BALB/c mice received an intragastric administration of 0.1 ml of a suspension of H. pylori. The mice were then divided into 4 groups: group A, treated with saline; group B, treated with 1.5 g of rhLF; group C, treated with the standard triple therapy regimen; and group D, treated with the standard triple therapy regimen plus.5 g of rhLF. Following sacrifice, the stomach tissues of the mice were histologically examined for the presence of bacteria. For the in vitro experiments, the bacteria were cultured in BHI broth and RT-qPCR and western blot analysis were carried out to determine the mRNA and protein levels of virulence factors (CagA and VacA) in the cultures. Our results revealed that rhLf not only inhibited the growth of H. pylori, but also suppressed the expression of two major virulence factors. Moreover, rhLf markedly increased bacterial eradication and effectively reduced the inflammatory response when combined with the standard triple therapy regimen. These results provide evidence supporting the use of rhLF as an adjuvant to traditional therapeutic strategies in the treatment of H. pylori. PMID:26080893

  3. Pneumatocele selar a tensión: Reporte de un caso y revisión de la literatura

    PubMed Central

    Campero, Álvaro; Ajler, Pablo; Goldschmidt, Ezequiel; Bendersky, Damián; Campero, Abraham

    2012-01-01

    Introducción: El neumoencéfalo a tensión luego de la cirugía transesfenoidal es poco común. En la literatura existen pocos casos reportados en los cuales el aire se encuentra localizado exclusivamente en las regiones selar y supraselar, constituyendo un pneumatocele selar. En este artículo se describe un caso inusual de pneumatocele selar a tensión de presentación tardía. Descripción del caso: Una mujer de 57 años consultó por hemianopsia bitemporal. Previamente, ya se le había realizado una cirugía transnasal por un adenoma hipofisario y se le había colocado una derivación lumbo-peritoneal por la presencia de una fístula de líquido cefalorraquídeo. Además, se le había realizado una resección transcraneal de un componente intracavernoso del tumor y radiocirugía debido a la agresividad del mismo. Se llevó a cabo una resonancia magnética que demostró un pneumatocele selar y supraselar. Intervención: Se realizó un abordaje transciliar. La región selar estaba encapsulada por tejido cicatrizal debido a los procedimientos previos. Se abrió la cicatriz y el aire fue evacuado. Posteriormente, el piso selar fue cerrado con grasa y cola de fibrina. Despuós del procedimiento, su campo visual retornó a la normalidad. Un año después de su última cirugía, continua asintomática. Conclusión: El pneumatocele selar y supraselar a tensión es un hallazgo extremadamente raro luego de una cirugía transesfenoidal. Su manifestaciónw clínica sería la alteración visual debida a la compresión inferior de la vía óptica. El pneumatocele selar a tensión debe ser evacuado en un corto plazo. PMID:23596554

  4. VIII Olimpíada Brasileira de Astronomia e Astronáutica

    NASA Astrophysics Data System (ADS)

    Garcia Canalle, João Batista; Villas da Rocha, Jaime Fernando; Wuensche de Souza, Carlos Alexandre; Pereira Ortiz, Roberto; Aguilera, Nuricel Villalonga; Padilha, Maria De Fátima Catta Preta; Pessoa Filho, José Bezerra; Soares Rodrigues, Ivette Maria

    2007-07-01

    Neste trabalho apresentamos as motivações pelas quais organizamos, em conjunto, pela primeira vez, a Olimpíada Brasileira de Astronomia incluindo a Astronáutica, em colaboração com a Agência Espacial Brasileira. Esta ampliação contribuiu para atrair ainda mais alunos, professores, escolas e patrocinadores para participarem desta Olimpíada. Em 2005 participaram da VIII Olimpíada Brasileira de Astronomia e Astronáutica (VIII OBA) 187.726 alunos distribuídos por 3.229 escolas, pertencentes a todos os estados brasileiros, incluindo o Distrito Federal. O crescimento em número de alunos participantes foi 52,4% maior do que em 2004. Em abril de 2005 organizamos, em Itapecerica da Serra, SP, um curso para os 50 alunos previamente selecionados e participantes da VII OBA e ao final selecionamos, dentre eles, uma equipe de 5 alunos, os quais representaram o Brasil na X Olimpíada Internacional de Astronomia, na China, em outubro de 2005. Ganhamos, pela primeira vez, uma medalha de ouro naquele evento. Em Agosto de 2005, organizamos a VIII Escola de Agosto para 50 alunos e respectivos professores, em Águas de Lindóia, SP, juntamente com a XXXI reunião anual da Sociedade Astronômica Brasileira (SAB). Em novembro de 2005 realizamos a I Jornada Espacial, em São José dos Campos, com 22 alunos e 22 professores selecionados dentre os participantes que melhores resultados obtiveram nas questões de Astronáutica da VIII OBA. Neste trabalho detalhamos os resultados da VIII OBA bem como as ações subseqüentes.

  5. Abundâncias químicas de estrelas T Tauri fracas

    NASA Astrophysics Data System (ADS)

    Rojas, G. A.; Gregorio-Hetem, J.

    2003-08-01

    Apresentamos resultados do estudo de 44 estrelas pré-seqüência principal, para as quais buscamos realizar uma classificação espectroscópica e determinar parâmetros estelares e abundâncias químicas. A amostra foi escolhida da seguinte maneira : 21 objetos selecionados a partir de catálogos de objetos jovens, como o Pico dos Dias Survey e o Herbig Bell Catalogue, e 23 objetos selecionados a partir de contrapartidas ópticas de fontes de raios X detectadas pelo satélite ROSAT. Dentre 24 objetos previamente classificados como estrelas T Tauri Fracas, apenas 7 revelaram ser realmente pertencentes à essa classe, sendo os demais objetos T Tauri Clássicas ou estrelas evoluídas da pré-seqüência principal. Esse resultado demonstra que o critério mais utilizado para distinguir as T Tauri Clássicas das T Tauri Fracas, baseado na largura equivelente da emissão Ha, não é suficiente para determinar o estágio evolutivo desses objetos. Para o cálculo de parâmetros estelares e abundâncias, foram escolhidas as estrelas que apresentam características ideais para esse tipo de estudo, como ausência de velamento, baixa velocidade de rotação e espectros com razão sinal-ruído adequada. Os parâmetros estelares como temperatura efetiva e gravidade foram determinados através do equilíbrio de excitação e ionização das linhas de Ferro, e as abundâncias químicas foram calculadas utilizando o método de síntese espectral. Serão apresentados os parâmetros estelares e as abundâncias de Lítio para toda a amostra, e abundâncias de vários elementos quimicos para 7 estrelas estudadas em maior detalhe

  6. Anisotropy of Magnetic Susceptibility: a petrofrabric tool for understanding mechanisms of fold and thrust belt evolution. Application in Malargüe FTB, Argentina

    NASA Astrophysics Data System (ADS)

    Branellec, Matthieu; Callot, Jean Paul; Aubourg, Charles; Nivière, Bertrand; Ringenbach, Jean Claude

    2013-04-01

    In fold and thrust belts (FTB), sedimentary beds are folded and faulted but rocks do not always show evidence of strong internal deformation. Nevertheless, several studies have demonstrated that a weak internal deformation (layer parallel shortening) can be recorded at the matrix scale before any macroscopic deformation. The Anisotropy of Magnetic susceptibility (AMS) provides information about the preferred orientation of billions of magnetic minerals. It enables the definition of a magnetic fabric, which may be visualized as an ellipsoid with principal axes K1 ? K2 ? K3. Basic elements of a magnetic fabric are the magnetic foliation (K1-K2 plane) and the magnetic lineation (K1 axe), when they are statistically defined. Both are related to strain-controlled petrofrabric. The Neuquén Basin is a wide intracratonic sag basin with complex and polyphased/diachronic evolution. The Pacific subduction and south Atlantic opening were the mechanisms controlling the large scale geodynamic framework. By late Triassic times, continental scale extension initiated fault-related narrow rift depocenters which later evolved toward a sag basin from middle Jurassic to upper Cretaceous. At that time, the basin started to record the compressive stress regime from the Pacific subduction. Three pulses of compressive deformation (Cretaceous, Paleogene and Miocene) are recorded in this retro-arc foreland setting. Approximately 300 samples have been collected from 30 sites in terrigenous rocks located along three cross sections from foothills to uplifted foreland area in Malargüe FTB. We mainly sample Kimmeridgian red beds of the Tordillo formation, Tithonian shales from the Vaca Muerta Fm, and late cretaceous red beds of the Neuquén Group. AMS fabrics are used as a proxy to measure accumulated microscopic finite strain and compares it with mesoscale (fractures) and macroscale structures (faults, folds…). This multi-scaled approach helps in defining a kinematic scenario for Malargüe FTB evolution by classifying magnetic fabrics related either to (1) sedimentary processes or (2) pre-folding layer parallel shortening (LPS) or (3) syn-folding kinematics depending on folding mode. Propagation of deformation in this case is neither uniform nor gradual. Therefore Malargüe FTB cannot be defined as a classical critical wedge; On the contrary extensional inheritance exerts a strong influence in localization of compressive deformation (LPS).

  7. Latitudinal Discontinuity in Thermal Conditions along the Nearshore of Central-Northern Chile

    PubMed Central

    Tapia, Fabian J.; Largier, John L.; Castillo, Manuel; Wieters, Evie A.; Navarrete, Sergio A.

    2014-01-01

    Over the past decade, evidence of abrupt latitudinal changes in the dynamics, structure and genetic variability of intertidal and subtidal benthic communities along central-northern Chile has been found consistently at 30–32°S. Changes in the advective and thermal environment in nearshore waters have been inferred from ecological patterns, since analyses of in situ physical data have thus far been missing. Here we analyze a unique set of shoreline temperature data, gathered over 4–10 years at 15 sites between 28–35°S, and combine it with satellite-derived winds and sea surface temperatures to investigate the latitudinal transition in nearshore oceanographic conditions suggested by recent ecological studies. Our results show a marked transition in thermal conditions at 30–31°S, superimposed on a broad latitudinal trend, and small-scale structures associated with cape-and-bay topography. The seasonal cycle dominated temperature variability throughout the region, but its relative importance decreased abruptly south of 30–31°S, as variability at synoptic and intra-seasonal scales became more important. The response of shoreline temperatures to meridional wind stress also changed abruptly at the transition, leading to a sharp drop in the occurrence of low-temperature waters at northern sites, and a concurrent decrease in corticated algal biomass. Together, these results suggest a limitation of nitrate availability in nearshore waters north of the transition. The localized alongshore change results from the interaction of latitudinal trends (e.g., wind stress, surface warming, inertial period) with a major headland-bay system (Punta Lengua de Vaca at 30.25°S), which juxtaposes a southern stretch of coast characterized by upwelling with a northern stretch of coast characterized by warm surface waters and stratification. This transition likely generates a number of latitude-dependent controls on ecological processes in the nearshore that can explain species-specific effects, and add strength to the suggestion of an oceanography-driven, major spatial transition in coastal communities at 30–31°S. PMID:25334020

  8. [What are the gastric modifications induced by acute and chronic Helicobacter pylori infection?].

    PubMed

    Lamarque, Dominique; Tran Van Nhieu, Jeanne; Breban, Maxime

    2003-03-01

    H. pylori colonisation of the stomach causes the recruitment of the inflammatory cells by the adherence of the bacteria with the epithelium and the release of factors of virulence either to the contact (oipA or other soluble factors) or in the cell by translocation (CagA). Such contact triggers interleukin 8 expression in the epithelial cell and attracts lymphocytes and monocytes into the chorion. Bacterial lipopolysaccharide and urease support the activation of these inflammatory cells. The lymphocytes produce pro-inflammatory cytokines, which direct the immune response towards the Th1 pathway. The variability of the inflammatory response depends on hereditary factors of the host such as the interleukin 1 genotypes, which determine the level of the pro-inflammatory cytokine expression, and of bacterial factors such as the cag pathogenicity island, the lipopolysaccharide and the vacuolating toxin, vacA. The mucosal inflammation provokes apoptosis and atrophy of the epithelial cells through the effect of pro-inflammatory cytokines and free radicals. Epithelial proliferation is a consequence of excessive apoptosis caused by the infection. It is stimulated by the expression of inducible cyclo-oxygenase and inducible nitric oxide synthase. The development of atrophic gastritis towards cancer is supported by nitric oxide which has a mutagenic effect on DNA and inhibits p53 protein and by the bacterium itself which decreases DNA mismatch repairing activity. The gastritis induced by Helicobacter pylori changes acid secretion according to the prevalent location of the gastritis in the antrum or in the gastric body. Prevalent gastritis in the gastric body causes hypochlorhydria by reducing the release of histamin from ECL cells and inhibiting the parietal cells through the effect of tumor necrosis factor and interleukin 1-beta. Hypochlorhydria is more marked among patients having a pro-inflammatory genotype for interleukin 1-beta and those infected by bacteria with virulence factors. In the event of antrum predominant gastritis, the pro-inflammatory cytokines cause a reduction of somatostatin and gastrin releases from the D and the G cells, respectively. The result of all is increased maximal acid output and the meal-stimulated acid secretion. PMID:12700495

  9. Geochemistry and oxygen isotope composition of main-group pallasites and olivine-rich clasts in mesosiderites: Implications for the "Great Dunite Shortage" and HED-mesosiderite connection

    NASA Astrophysics Data System (ADS)

    Greenwood, Richard C.; Barrat, Jean-Alix; Scott, Edward R. D.; Haack, Henning; Buchanan, Paul C.; Franchi, Ian A.; Yamaguchi, Akira; Johnson, Diane; Bevan, Alex W. R.; Burbine, Thomas H.

    2015-11-01

    Evidence from iron meteorites indicates that a large number of differentiated planetesimals formed early in Solar System history. These bodies should have had well-developed olivine-rich mantles and consequentially such materials ought to be abundant both as asteroids and meteorites, which they are not. To investigate this "Great Dunite Shortage" we have undertaken a geochemical and oxygen isotope study of main-group pallasites and dunitic rocks from mesosiderites. Oxygen isotope analysis of 24 main-group pallasites (103 replicates) yielded a mean ?17O value of -0.187 ± 0.016‰ (2?), which is fully resolved from the HED ?17O value of -0.246 ± 0.014 (2?) obtained in our earlier study and demonstrates that both groups represent distinct populations and were derived from separate parent bodies. Our results show no evidence for ?17O bimodality within the main-group pallasites, as suggested by a number of previous studies. Olivine-rich materials from the Vaca Muerta, Mount Padbury and Lamont mesosiderites, and from two related dunites (NWA 2968 and NWA 3329), have ?17O values within error of the mesosiderite average. This indicates that these olivine-rich materials are co-genetic with other mesosiderite clasts and are not fragments from an isotopically distinct pallasite-like impactor. Despite its extreme lithologic diversity the mesosiderite parent body was essentially homogeneous with respect to ?17O, a feature best explained by an early phase of large-scale melting (magma ocean), followed by prolonged igneous differentiation. Based on the results of magma ocean modeling studies, we infer that Mg-rich olivines in mesosiderites formed as cumulates in high-level chambers and do not represent samples of the underlying mantle. By analogy, recently documented Mg-rich olivines in howardites may have a similar origin. Although the Dawn mission did not detect mesosiderite-like material on Vesta, evidence linking the mesosiderites and HEDs includes: (i) their nearly identical oxygen isotope compositions; (ii) the presence in both of coarse-grained Mg-rich olivines; (iii) both have synchronous Lu-Hf and Mn-Cr ages; (iv) there are compositional similarities between the metal in both; and (v) mesosiderite-like material has been identified in a howardite breccia. The source of the mesosiderites remains an outstanding question in meteorite science. The underrepresentation of olivine-rich materials amongst both asteroids and meteorites results from a range of factors. However, evidence from pallasites and mesosiderites indicates that the most important reason for this olivine shortage lies in the early, catastrophic destruction of planetesimals in the terrestrial planet-forming region and the subsequent preferential loss of their olivine-rich mantles.

  10. Distinct aetiopathogenesis in subgroups of functional dyspepsia according to the Rome III criteria

    PubMed Central

    Fang, Yu-Jen; Liou, Jyh-Ming; Chen, Chieh-Chang; Lee, Ji-Yuh; Hsu, Yao-Chun; Chen, Mei-Jyh; Tseng, Ping-Huei; Chen, Chien-Chuan; Chang, Chi-Yang; Yang, Tsung-Hua; Chang, Wen-Hsiung; Wu, Jeng-Yi; Wang, Hsiu-Po; Luo, Jiing-Chyuan; Lin, Jaw-Town; Shun, Chia-Tung; Wu, Ming-Shiang

    2015-01-01

    Background and objective Whether there is distinct pathogenesis in subgroups of functional dyspepsia (FD), the postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS) remains controversial. We aimed to identify the risk factors of FD and its subgroups in the Chinese population. Methods Patients with dyspepsia and healthy subjects who underwent gastric cancer screening were enrolled in this multicentre study from 2010 to 2012. All patients were evaluated by questionnaire, oesophagoduodenoscopy, histological examination and Helicobacter pylori tests. Subgroups of FD were classified according to the Rome III criteria. Psychiatric stress was assessed by the short form Brief Symptom Rating Scale. CagA and VacA genotypes were determined by PCR. Results Of 2378 patients screened for eligibility, 771 and 491 fulfilled the diagnostic criteria of uninvestigated dyspepsia and FD, respectively. 298 (60.7%) and 353 (71.9%) individuals were diagnosed with EPS and PDS, respectively, whereas 169 (34.4%) had the overlap syndrome. As compared with 1031 healthy controls, PDS and EPS shared some common risk factors, including younger age (OR 0.95; 99.5% CI 0.93 to 0.98), non-steroidal anti-inflammatory drugs (OR 6.60; 99.5% CI 3.13 to 13.90), anxiety (OR 3.41; 99.5% CI 2.01 to 5.77) and concomitant IBS (OR 6.89; 99.5% CI 3.41 to 13.94). By contrast, H. pylori (OR 1.86; 99.5% CI 1.01 to 3.45), unmarried status (OR 4.22; 99.5% CI 2.02 to 8.81), sleep disturbance (OR 2.56; 99.5% CI 1.29 to 5.07) and depression (OR 2.34; 99.5% CI 1.04 to 5.36) were associated with PDS. Moderate to severe antral atrophy and CagA positive strains were also more prevalent in PDS. Conclusions Different risk factors exist among FD subgroups based on the Rome III criteria, indicating distinct aetiopathogenesis of the subdivisions that may necessitate different therapeutic strategies. PMID:25406127

  11. N2,7-bis(1-hydroxy-2-oxopropyl)-2'-deoxyguanosine: identical noncyclic adducts with 1,3-dichloropropene epoxides and methylglyoxal.

    PubMed

    Schneider, M; Quistad, G B; Casida, J E

    1998-12-01

    cis- and trans-1,3-dichloropropene epoxides (1,3-D-epoxides) are proposed to be the penultimate or ultimate genotoxic metabolites of the major soil fumigant nematicide 1,3-dichloropropene. The 1, 3-D-epoxide isomers and the potential aldehydes from their degradation readily form adducts with 2'-deoxyguanosine (dGuo) but not with 2'-deoxyadenosine or 2'-deoxycytidine. The reaction of dGuo with the 1,3-D-epoxides (1:20 molar equiv) in phosphate buffer at pH 7.4 for 24 h at 37 degreesC results in complete conversion to four adducts that can be separated by HPLC with the same UV spectra and electrospray (ES)/MS molecular ion and fragmentation patterns. These adducts contain no chlorine and are identical to those obtained more rapidly with methylglyoxal in place of the 1,3-D-epoxides. The four isomeric methylglyoxal adducts with dGuo were proposed originally by others to be the cyclic adducts 1,N2-(1, 2-dihydroxy-2-methyl)ethano-dGuo, but they are reassigned here as the four diastereomers of the noncyclic bis adducts N2, 7-bis(1-hydroxy-2-oxopropyl)-dGuo. The assignments are based on HPLC/UV and HPLC/ES/MS experiments and 1H NMR spectral analysis of the first of the four adducts eluted with HPLC. Acid-catalyzed depurination converts the four dGuo derivatives to the two corresponding isomers of N2,7-bis(1-hydroxy-2-oxopropyl)guanine, assigned by ES/MS and 1H and 13C NMR. Although identical adducts are formed from dGuo with the 1,3-D-epoxides or methylglyoxal, the latter alpha,beta-dicarbonyl compound is not an intermediate in the reaction; instead, the 1,3-D-epoxides hydrolyze to 3-chloro-2-hydroxypropanal which adds to dGuo at N2 and N7. The adducts dehydrochlorinate, in a rate-limiting reaction, thereby giving the same end products obtained on direct reaction with methylglyoxal. Thus, 3-chloro-2-hydroxypropanal (not the 1, 3-D-epoxides or methylglyoxal) is the derivatizing agent for dGuo and therefore probably the mutagenic agent on 1,3-D bioactivation. On the basis of the dGuo model studied here, the DNA adducts of 1, 3-D and its epoxides may be the same as those with methylglyoxal [Vaca, C. E., Fang, J.-L., Conradi, M., and Hou, S.-M. (1994) Carcinogenesis 15, 1887-1894]. PMID:9860499

  12. Are sills really elastic hydraulic fractures?

    NASA Astrophysics Data System (ADS)

    Spacapan, Juán B.; Galland, Olivier; Leanza, Héctor A.; Planke, Sverre

    2015-04-01

    Seismic reflection data and field observations have over the past few decades revealed the presence of voluminous igneous sill complexes in sedimentary basins worldwide. The implications of sill emplacement in sedimentary basins are numerous: they trigger maturation of organic-rich formations, they produce large quantities of greenhouse gases that trigger dramatic climate change and mass extinctions, and they produce small- and large-scale structures that affect fluid flow. Therefore, a proper understanding of their emplacement mechanism is essential. Most models of sill and laccolith emplacement account for purely elastic host rock, and their propagation mechanism is dominantly assumed to be according to the Linear Elastic Fracture Mechanics (LEFM) theory. Recent field and seismic observations, however, demonstrated that part, if not all, sill- and laccolith-induced deformation is accommodated by inelastic deformation, strongly questioning the relevance of the LEFM theory applied for igneous intrusions. In this contribution, we present detailed structural observations from spectacularly well-exposed sills in the northern Neuquén Basin, Argentina. We studied a 50-m outcrop that exhibits very clearly three sills of different sizes, the shapes of their tips, and the associated structures in their sedimentary host rock, i.e. the calcareous pelites of the organic-rich Vaca Muerta Fm. This formation is adequate to map the structures at the outcrop scale, as it consists in fine layers of mudstone inter-bedded with weak shale, such that it is possible to map each layer along the entire outcrop. Detailed structural mapping evidence that the sedimentary layers have not been opened, i.e. pushed away by the emplacement of the sills, as expected from the LEFM theory. Indeed, some of the sedimentary layers are not present at the location of the sills, but they appear duplicated several times ahead of the tips of the three observed sills; the relative movements between the duplicated segments are clearly associated with shortening. Therefore, our field observations show that the host rock is pushed and shortened ahead of the sill tips, in total contradiction with the extensional features predicted by the LEFM theory. The structures described above strongly suggest instead that these sills were emplaced according to the viscous indenter model, in good agreement with recent laboratory models (Abdelmalak et al., 2012). These detailed observations strongly question the geological relevance of the LEFM theory applied to igneous sheet intrusions, and call for more field observations to better constrain the dynamics of sill and dyke emplacement mechanisms. Abdelmalak, M.M., Mourgues, R., Galland, O., Bureau, D., 2012. Fracture mode analysis and related surface deformation during dyke intrusion: Results from 2D experimental modelling. Earth Planet. Sci. Lett. 359-360, 93-105.

  13. Method for cutting steam heat losses during cyclic steam injection of wells. Second quarterly report

    SciTech Connect

    Not Available

    1994-08-01

    The Midway-Sunset Field (CA) is the largest Heavy Oil field in California and steam injection methods have been successfully used for more than 30 years to produce the Heavy Oil from many of its unconsolidated sand reservoirs. In partnership with another DOE/ERIP grantee, our Company has acquired an 80 ac. lease in the SE part of this field, in order to demonstrate our respective technologies in the Monarch sand, of Miocene Age, which is one of the reservoirs targeted by the DOE Class 3 Oil Program. This reservoir contains a 13 API oil, which has a much higher market value, as a Refinery Feedstock, than the 5 to 8 API Vaca Tar, used only as road paving material. This makes it easier to justify the required investment in a vertical well equipped with two horizontal drainholes. The economic viability of such a project is likely to be enhanced if Congress approves the export to Japan of a portion of the 27 API (1% Sulfur) AK North Slope oil, which currently is landed in California in preference to lighter and sweeter Far East imported crudes. This is a major cause of the depressed prices for California Heavy Oil in local refineries, which have reduced the economic viability of all EOR methods, including steam injection, in California. Two proposals, for a Near-Term (3 y.) and for a Mid-Term (6 y.) project respectively, were jointly submitted to the DOE for Field Demonstration of the Partners` new technologies under the DOE Class 3 Oil Program. The previous design of a special casing joint for the Oxnard field well was reviewed and adapted to the use of existing Downhole Hardware components from three suppliers, instead of one. The cost of drilling and completion of a well equipped with two horizontal drainholes was re-evaluated for the conditions prevailing in the Midway Sunset field, which are more favorable than in the Oxnard field, leading to considerable reductions in drilling rig time and cost.

  14. Planificación Neuroquirúrgica con Software Osirix

    PubMed Central

    Jaimovich, Sebastián Gastón; Guevara, Martin; Pampin, Sergio; Jaimovich, Roberto; Gardella, Javier Luis

    2014-01-01

    Introducción: La individualidad anatómica es clave para reducir el trauma quirúrgico y obtener un mejor resultado. Actualmente, el avance en las neuroimágenes ha permitido objetivar esa individualidad anatómica, permitiendo planificar la intervención quirúrgica. Con este objetivo, presentamos nuestra experiencia con el software Osirix. Descripción de la técnica: Se presentan 3 casos ejemplificadores de 40 realizados. Caso 1: Paciente con meningioma de la convexidad parasagital izquierda en área premotora; Caso 2: Paciente con macroadenoma hipofisario, operada previamente por vía transeptoesfenoidal en otra institución con una resección parcial; Caso 3: Paciente con lesiones en pedúnculo cerebeloso medio bilateral. Se realizó la planificación prequirúrgica con el software OsiriX, fusionando y reconstruyendo en 3D las imágenes de TC e IRM, para analizar relaciones anatómicas, medir distancias, coordenadas y trayectorias, entre otras funciones. Discusión: El software OsiriX de acceso libre y gratuito permite al cirujano, mediante la fusión y reconstrucción en 3D de imágenes, analizar la anatomía individual del paciente y planificar de forma rápida, simple, segura y económica cirugías de alta complejidad. En el Caso 1 se pudo analizar las relaciones del tumor con las estructuras adyacentes para minimizar el abordaje. En el Caso 2 permitió comprender la anatomía post-operatoria previa del paciente, para determinar la trayectoria del abordaje transnasal endoscópico y la necesidad de ampliar su exposición, logrando la resección tumoral completa. En el Caso 3 permitió obtener las coordenadas estereotáxicas y trayectoria de una lesión sin representación tomográfica. Conclusión: En casos de no contar con costosos sistemas de neuronavegación o estereotáxia el software OsiriX es una alternativa a la hora de planificar la cirugía, con el objetivo de disminuir el trauma y la morbilidad operatoria. PMID:25165617

  15. Moléculas orgánicas obtenidas en simulaciones experimentales del medio interestelar.

    NASA Astrophysics Data System (ADS)

    Muñoz-Caro, Guillermo Manuel

    Las nubes moleculares son regiones de formación de estrellas, con temperaturas cinéticas entre 10-50 K y densidades de 103-106 átomos cm-3. Su materia está formada por gas y polvo interestelar. Estas partículas de polvo están cubiertas por una fina capa de hielo, de unos 0.01 ?m, que contiene H2O y a menudo CO, CO2, CH3OH y NH3. El hielo es presumiblemente irradiado por fotones ultravioleta y rayos cósmicos en las zonas poco profundas de las nubes moleculares y las regiones circunestelares. En un sistema de vacío, P ˜ 10-7 mbar, simulamos la deposición de hielo a partir de 10 K y la irradiación ultravioleta por medio de una lámpara de descarga de hidrógeno activada con microondas. La evolución del hielo se observa por medio de un espectrómetro infrarrojo. De este modo es posible determinar la composición del hielo observado en el medio interestelar y predecir la presencia de moléculas aún no detectadas en el espacio, que han sido producto del procesamiento del hielo en nuestros experimentos. También es posible calentar el sistema hasta temperatura ambiente para sublimar el hielo depositado. Cuando el hielo ha sido previamente irradiado, se observa un residuo compuesto por moléculas orgánicas complejas, algunas prebióticas, como varios ácidos carboxílicos, aminas, amidas, ésteres y en menor proporción moléculas heterocíclicas y aminoácidos. Algunas de estas moléculas podrían detectarse en estado gaseoso por medio de observaciones milimétricas y de radio. También podrían estar presentes en el polvo cometario, cuyo análisis químico está planeado por las misiones Stardust y Rosetta. Mientras tanto, nuestro grupo está llevando a cabo el análisis de partículas de polvo interplanetario (IDPs), algunas de las cuales pueden ser de origen cometario. Al igual que ocurre con los productos obtenidos por irradiación del hielo en nuestros experimentos, algunas IDPs son ricas en material orgánico que contiene oxígeno.

  16. Delineation of the High Enthalpy Reservoirs of the Sierra Nevada Volcanic Geothermal System, South-Central Chile

    NASA Astrophysics Data System (ADS)

    Alam, M.; Muñoz, M.; Parada, M.

    2011-12-01

    Geothermal system associated with the Pleistocene-Holocene Sierra Nevada volcano (SNVGS) in the Araucanía Region of Chile has surface manifestations from the north-western flank of the volcano, up to Manzanar and Malalcahuello. Baños del Toro, located on the northwestern flank of the volcano, has numerous fumaroles and acid pools (acid sulfate waters, T=~90°C, pH=2.1, TDS=3080 mg/L); while Aguas de la Vaca, near the base of the volcano, has a bubbling spring (chloride-sulfate waters, T=~60°C, pH=7.0, TDS=950 mg/L). Five shallow (<120m) wells (2 at Manzanar and 3 at Malalcahuello) dug and drilled in the Cautín River Valley discharge alkaline (pH= 9-10) waters with relatively low TDS (130-210mg/L). The main heat source of the geothermal system is apparently the magmatic system of the Sierra Nevada volcano. Liquiñe-Ofqui Fault Zone (LOFZ) that transects the area forms excellent conduits for the flow of the geothermal waters. The geothermal reservoirs are hosted in the volcanic rocks interceded with glacial deposits over the North Patagonian Batholith that forms an impermeable barrier, and thus constitutes the lower boundary of the geothermal system and also controls the lateral flow of the fluids. An equilibrium temperature of ~210°C is derived from gas geothermometry (CO2/Ar-H2/Ar) of the discharges at Baños del Toro. Geothermal fluids from the upflow area on the northwestern flank of the volcano migrate northwards to the Cautín River Valley. The geothermal system has a high enthalpy reservoir(s) on the northwestern flank of the Sierra Nevada volcano and low-enthalpy reservoirs in the Cautín River Valley that have been tapped to form spas at Manzanar and Malalcahuello. While sub-vertical fractures of LOFZ facilitate the recharge of the system, lateral flow of the geothermal fluids is apparently controlled by lithology; Melipueclo Pluton in particular prevents the westward flow from the upflow zone, causing the flow only northwards to Malalcahuello and subsequently westward on meeting poorly permeable Guapitrío Member of the Cura-Mallín Formation. This change in the flow direction from northwestward up to Malalcahuello to westward towards Manzanar is supported by topographic and hydrographic conditions as well, besides available geological and geophysical data. SNVGS is perhaps the most promising geothermal system in the area, considering the presence of high enthalpy reservoir and stable heat source, ideal for its development as geothermal resource. Acknowledgments: Authors would like to acknowledge the funding for this work through the PBCT PDA-07 project of CONICYT and Geothermal Program (Cátedra de Geotermia) of the Ministry of Energy and Mining, Government of Chile.

  17. Geology, water resources and usable ground-water storage capacity of part of Solano County, California

    USGS Publications Warehouse

    Thomasson, H.G., Jr.; Olmsted, F.H.; LeRoux, E.F.

    1960-01-01

    The area described is confined largely to the valley-floor and foothill lands of Solano County, which lies directly between Sacramento, the State capital, and San Francisco. The area is considered in two subareas: The Putah area, which extends from Putah Creek southward to the Montezuma Hills and from the foothills of the Coast Ranges eastward to the west edge of the Yolo Bypass; and the Suisun-Fairfield area, which is to the southwest in the notch in the Coast Ranges through which the waters of the Great Central Valley of California reach San Francisco Bay. There are no known hydrologic interconnections between the two subareas, through either surface streams or underground aquifers. The climate of the area is characterized by warm, rainless summers and by cool winters in which temperatures seldom drop much below freezing. The rainfall ranges from about 17 inches per year along the east side to perhaps 24 inches in the foothills to the west, and irrigation is necessary for all crops except dry-farmed grains, pastures, and some orchards. PUTAH AREA The Putah area occupies the southwestern corner of the Sacramento Valley, a topographic and structural basin underlain by a thick accumulation of sediments eroded from the surrounding hills and mountains by the Sacramento River and its tributaries. The eastern Coast Ranges and foothills lying west of the Sacramento Valley are a generally northward-trending belt of eastward-dipping sedimentary rocks that range in age from Cretaceous to Pleistocene. Successively younger strata are exposed eastward, and the essentially undeformed deposits of late Pleistocene and Recent age that immediately underlie the valley lap onto the tilted sediments of the foothills. Most of the streams of the Putah area rise east of the high ridge of Cretaceous rocks marking the western boundaries of Solano and Yolo Counties, but Putah Creek, the largest stream in the area, rises far west of that ridge and flows across it in a deep, narrow canyon. Putah Creek and the smaller streams have constructed an alluvial plain, herein designated the Putah plain, which slopes eastward and southeastward from the foothills toward the Sacramento River. A large part of the Putah plain is traversed by a branching set of distributary channel ridges or natural levees formed at times of overflow of Putah Creek. The rocks in the Putah area range in age from Cretaceous to Recent. For the purposes of this investigation they are divided into eight geologic or stratigraphic units, from youngest to oldest: (1) Stream-channel deposits, (2) younger alluvium, (3) older alluvium, (4) Tehama formation and related continental sediments, (5) volcanic sedimentary rocks, (6) basalt, (7) undifferentiated sedimentary rocks of Paleocene(?) and Eocene age, and (8) undifferentiated rocks of Cretaceous age. The stream-channel deposits are predominantly loose sand and gravel along the channel of Putah Creek. In part they are actively moving downstream and shifting. The younger alluvium, of Recent age, consists of flood-plain deposits underlying the Putah plain, Vaca Valley, Pleasants Valley, and the small valleys in the foothills north of Putah Creek and in the English Hills. Exposures of younger alluvium are characterized by soils lacking significant profile development and in many places by channel-ridge topography. The older alluvium occupies the stratigraphic interval between the younger alluvium and the Tehama formation and related continental sediments and is probably of late Pleistocene age. Its contact with the underlying Tehama formation and related continental sediments is unconformable near the foothills, but it may be gradational beneath much of the Putah plain. The base of the older alluvium is not well defined at many places but is inferred to be at the bottom of an irregular and ill-defined zone of coarse deposits, which ranges from about 50 feet to more than 150 feet below the land surface. Exposures of the older

  18. Potential effect of chronic Helicobacter pylori infection on glucose metabolism of Mongolian gerbils

    PubMed Central

    Yang, Zhen; Li, Wei; He, Cong; Xie, Chuan; Zhu, Yin; Lu, Nong-Hua

    2015-01-01

    AIM: To assess the effect of Helicobacter pylori (H. pylori) infection on metabolic parameters in Mongolian gerbils. METHODS: A total of 40 male, 5- to 8-wk-old, specific-pathogen-free Mongolian gerbils (30-50 g) were randomly allocated into two groups: a control group (n = 20) and an H. pylori group (n = 20). After a two-week acclimation period, the control group was administered Brucella broth and the H. pylori group was challenged intra-gastrically five times every other day with approximately 109/CFU H. pylori ATCC43504 (CagA+, VacA+). Each group was then divided into two subgroups, which were sacrificed at either 6 or 12 mo. The control and H. pylori subgroups each contained 10 Mongolian gerbils. Body weight, abdominal circumference, and body length were measured, and body mass index (BMI) and Lee’s index were calculated. Biochemical assays were used to detect serum indexes, including glucose, glycated hemoglobin (GHb), glycated hemoglobin A1c (HbA1c), triacylglycerol, and total cholesterol, using an automatic biochemistry analyzer. Inflammatory cytokines, including interleukin (IL)-1?, IL-2, IL-4, IL-10, IL-12, tumor necrosis factor-? (TNF-?) and interferon (IFN)-?, were assayed using ELISA. The expression of insulin and insulin-like growth factor 1 (IGF-1) was detected by immunohistochemistry, and islet apoptosis was measured using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. RESULTS: At each time point, body weight, abdominal circumference, BMI, and Lee’s index were increased after H. pylori infection. However, these differences were not significant. H. pylori infection significantly increased the GHb (5.45 ± 0.53 vs 4.98 ± 0.22, P < 0.05) and HbA1c (4.91 ± 0.61 vs 4.61 ± 0.15, P < 0.05) levels at 12 mo. We observed no significant differences in serum biochemical indexes, including fasting blood glucose, triacylglycerol and total cholesterol, at 6 or 12 mo after infection. H. pylori infection significantly increased the expression of IGF-1 (P < 0.05). Insulin levels from the pancreas and the apoptotic rate of islet ?-cells remained unchanged. Also, we observed no significant differences among cytokines levels, including IL-1?, IL-2, IL-4, IL-10, IL-12, TNF-? and IFN-?. IL-4 was the only exception, which increased at 6 (44.36 ± 25.17 vs 17.38 ± 3.47, P < 0.05) and 12 mo (33.41 ± 10.00 vs 18.91 ± 5.31, P < 0.05) after H. pylori infection. CONCLUSION: Long-term H. pylori infection is significantly associated with high levels of HbA1c in Mongolian gerbils, indicating a potential role of H. pylori infection in glucose dysregulation. PMID:26640335

  19. Using operational data to estimate the reliable yields of water-supply wells

    NASA Astrophysics Data System (ADS)

    Misstear, Bruce D. R.; Beeson, Sarah

    The reliable yield of a water-supply well depends on many different factors, including the properties of the well and the aquifer; the capacities of the pumps, raw-water mains, and treatment works; the interference effects from other wells; and the constraints imposed by ion licences, water quality, and environmental issues. A relatively simple methodology for estimating reliable yields has been developed that takes into account all of these factors. The methodology is based mainly on an analysis of water-level and source-output data, where such data are available. Good operational data are especially important when dealing with wells in shallow, unconfined, fissure-flow aquifers, where actual well performance may vary considerably from that predicted using a more analytical approach. Key issues in the yield-assessment process are the identification of a deepest advisable pumping water level, and the collection of the appropriate well, aquifer, and operational data. Although developed for water-supply operators in the United Kingdom, this approach to estimating the reliable yields of water-supply wells using operational data should be applicable to a wide range of hydrogeological conditions elsewhere. Résumé La productivité d'un puits capté pour l'adduction d'eau potable dépend de différents facteurs, parmi lesquels les propriétés du puits et de l'aquifère, la puissance des pompes, le traitement des eaux brutes, les effets d'interférences avec d'autres puits et les contraintes imposées par les autorisations d'exploitation, par la qualité des eaux et par les conditions environnementales. Une méthodologie relativement simple d'estimation de la productivité qui prenne en compte tous ces facteurs a été mise au point. Cette méthodologie est basée surtout sur une analyse des données concernant le niveau piézométrique et le débit de prélèvement, quand ces données sont disponibles. De bonnes données opérationnelles sont particulièrement importantes quand il s'agit de puits dans des aquifères fissurés, libres et peu profonds, dans lesquels la performance réelle d'un puits peut varier considérablement de celle prédite à partir d'une approche plus analytique. Des données essentielles dans les processus d'estimation de la productivité sont l'identification d'un niveau piézométrique de pompage le plus profond possible et le recueil de données opérationnelles appropriées concernant le puits et l'aquifère. Bien qu'elle ait été développée pour des opérateurs gérant des captages en Grande-Bretagne, cette approche de l'estimation de la productivité des puits de captage d'eau potable à partir de données opérationnelles peut être appliquée à une large gamme de conditions hydrogéologiques en d'autres lieux. Resumen La productividad de un pozo de abastecimiento depende de varios factores, entre los que se incluyen las propiedades del pozo y del acuífero, la capacidad de la bomba, las obras de mantenimiento, la interferencia de otras captaciones y las restricciones impuestas por permisos legales, calidad del agua y aspectos ambientales. Se ha desarrollado una metodología relativamente simple para estimar la productividad de un pozo teniendo en cuenta todos los factores previamente mencionados. Esta metodología se basa principalmente en el análisis de niveles y caudales cuando estos datos están disponibles. Se requieren buenos datos de operación, principalmente cuando el pozo está situado en un acuífero de poco espesor, no confinado y en medio fracturado, donde la respuesta del sistema puede diferir enormemente de la predicción analítica. Un punto destacado en el estudio de productividad es la identificación del descenso máximo admisible. Aunque desarrollada para el Reino Unido, la metodología puede ser utilizada a un amplio rango de condiciones hidrogeológicas en otras zonas del mundo.

  20. The conceptualization model problem—surprise

    NASA Astrophysics Data System (ADS)

    Bredehoeft, John

    2005-03-01

    The foundation of model analysis is the conceptual model. Surprise is defined as new data that renders the prevailing conceptual model invalid; as defined here it represents a paradigm shift. Limited empirical data indicate that surprises occur in 20-30% of model analyses. These data suggest that groundwater analysts have difficulty selecting the appropriate conceptual model. There is no ready remedy to the conceptual model problem other than (1) to collect as much data as is feasible, using all applicable methods—a complementary data collection methodology can lead to new information that changes the prevailing conceptual model, and (2) for the analyst to remain open to the fact that the conceptual model can change dramatically as more information is collected. In the final analysis, the hydrogeologist makes a subjective decision on the appropriate conceptual model. The conceptualization problem does not render models unusable. The problem introduces an uncertainty that often is not widely recognized. Conceptual model uncertainty is exacerbated in making long-term predictions of system performance. C'est le modèle conceptuel qui se trouve à base d'une analyse sur un modèle. On considère comme une surprise lorsque le modèle est invalidé par des données nouvelles; dans les termes définis ici la surprise est équivalente à un change de paradigme. Des données empiriques limitées indiquent que les surprises apparaissent dans 20 à 30% des analyses effectuées sur les modèles. Ces données suggèrent que l'analyse des eaux souterraines présente des difficultés lorsqu'il s'agit de choisir le modèle conceptuel approprié. Il n'existe pas un autre remède au problème du modèle conceptuel que: (1) rassembler autant des données que possible en utilisant toutes les méthodes applicables—la méthode des données complémentaires peut conduire aux nouvelles informations qui vont changer le modèle conceptuel, et (2) l'analyste doit rester ouvert au fait que le modèle conceptuel peut bien changer lorsque des nouvelles informations apparaissent. Dans l'analyse finale le hydrogéologue prend une décision subjective sur le modèle conceptuel approprié. Le problème du le modèle conceptuel ne doit pas rendre le modèle inutilisable. Ce problème introduit une incertitude qui n'est pas toujours reconnue. Les incertitudes du modèle conceptuel deviennent plus importantes dans les cases de prévisions à long terme dans l'analyse de performance. La base para hacer un análisis de un modelo es el modelo conceptual. Se define aquí la sorpresa como los datos nuevos que convierten en incoherente al modelo conceptual previamente aceptado; tal como se define aquí esto representa un cambio de paradigma. Los datos empíricos limitados indican que estas sorpresas suceden entre un 20 a un 30% de los análisis de modelos. Esto sugiere que los analistas de modelos de agua subterránea tienen dificultades al seleccionar el modelo conceptual apropiado. No hayotra solución disponible a este problema del modelo conceptual diferente de: (1) Recolectar tanta información como sea posible, mediante la utilización de todos los métodos aplicables, lo cual puede resultar en que esta nueva información ayude a cambiar el modelo conceptual vigente, y (2) Que el analista de modelos se mantenga siempre abierto al hecho de que un modelo conceptual puede cambiar de manera total, en la medida en que se colecte mas información. En el análisis final el hidrogeólogo toma una decisión subjetiva en cuanto al modelo conceptual apropiado. El problema de la conceptualización no produce modelos inútiles. El problema presenta una incertidumbre, la cual a menudo no es tenida en cuentade manera adecuada. Esta incertidumbre en los modelos conceptuales se aumenta, cuando se hacen predicciones a largo plazo del comportamiento de un sistema dado.

  1. Hydrodynamic model of cells for designing systems of urban groundwater drainage

    NASA Astrophysics Data System (ADS)

    Zimmermann, Eric; Riccardi, Gerardo

    2000-08-01

    An improved mathematical hydrodynamic quasi-two-dimensional model of cells, CELSUB3, is presented for simulating drainage systems that consist of pumping well fields or subsurface drains. The CELSUB3 model is composed of an assemblage of algorithms that have been developed and tested previously and that simulate saturated flow in porous media, closed conduit flow, and flow through pumping stations. A new type of link between aquifer cells and drainage conduits is proposed. This link is verified in simple problems with well known analytical solutions. The correlation between results from analytical and mathematical solutions was considered satisfactory in all cases. To simulate more complex situations, the new proposed version, CELSUB3, was applied in a project designed to control the water-table level within a sewer system in Chañar Ladeado Town, Santa Fe Province, Argentina. Alternative drainage designs, which were evaluated under conditions of dynamic recharge caused by rainfall in a critical year (wettest year for the period of record) and a typical year, are briefly described. After analyzing ten alternative designs, the best technical-economic solution is a subsurface drainage system of closed conduits with pumping stations and evacuation channels. Résumé. Un modèle hydrodynamique perfectionné de cellules en quasi 2D, CELSUB3, est présenté dans le but de simuler des systèmes de drainage qui consistent en des champs de puits de pompage ou de drains souterrains. Le modèle CELSUB3 est composé d'un assemblage d'algorithmes développés et testés précédemment et qui simulent des écoulements en milieu poreux saturé, en conduites et dans des stations de pompage. Un nouveau type de lien entre des cellules d'aquifères et des drains est proposé. Ce lien est vérifié dans des problèmes simples dont les solutions analytiques sont bien connues. La corrélation entre les résultats des solutions analytiques et des solutions mathématiques a été considérée comme satisfaisante dans tous les cas. Afin de simuler des situations plus complexes, la nouvelle version proposée, CELSUB3, a été mise en œuvre dans un projet destiné à contrôler le niveau de la nappe à l'intérieur d'un système d'égouts, dans la ville de Chaar Ladeado (province de Santa Fe, Argentine). Différentes organisations du projet de drainage, qui ont été testées pour des conditions de recharge dynamique causées par la pluie au cours d'une année critique (la plus humide de la chronique disponible) et une année typique, sont brièvement décrites. Après analyse de dix organisations différentes, la meilleure solution technico-économique retenue est un système de drainage souterrain de conduites avec des stations de pompage et des canaux d'évacuation. Resumen. Se presenta un modelo matemático hidrodinámico cuasi-bidimensional de celdas, CELSUB3, apto para la simulación integral de sistemas de drenaje subterráneo basados en campos de bombeo o drenes subsuperficiales. El modelo de simulación presenta un ensamble de algoritmos, previamente desarrollados y testeados, que representan al escurrimiento a través del medio poroso saturado, escurrimiento en conducciones cerradas, estaciones de bombeo, etc. En la estructura del modelo se propone un nuevo tipo de vinculación entre celdas acuíferas y conductos de drenaje, la cual es verificada en problemas simples con solución analítica conocida arrojando, en todos los casos, resultados satisfactorios. Abordando situaciones más complejas, la nueva versión propuesta fue aplicada en un proyecto de control de niveles freáticos que acompaña un sistema de conductos cloacales, en la localidad de Chañar Ladeado, Santa Fe, Argentina. Se describen las alternativas de drenaje consideradas las cuales fueron evaluadas bajo recargas dinámicas provocadas por años críticamente lluviosos y en situaciones típicas. Los resultados derivados permitieron definir, tras analizar una decena de proyectos alternativos, la mejor solución técnico-económica consistente en un sistema de drenes subte

  2. Groundwater capture processes under a seasonal variation in natural recharge and discharge

    NASA Astrophysics Data System (ADS)

    Maddock, Thomas, III.; Vionnet, Leticia Beatriz

    "Capture" is the increase in recharge and the decrease in discharge that occurs when pumping is imposed on an aquifer system that was in a previous state of approximate dynamic equilibrium. Regional groundwater models are usually used to calculate capture in a two-step procedure. A steady-state solution provides an initial-head configuration, a set of flows through the boundaries for the modeled region, and the initial basis for the capture calculation. The transient solutions provide the total change in flows through the boundaries. A difference between the transient and steady-state solutions renders the capture calculation. When seasonality is a modeling issue, the use of a single initial hydraulic head and a single set of boundary flows leads to miscalculations of capture. Instead, an initial condition for each season should be used. This approach may be accomplished by determining steady oscillatory solutions, which vary through the seasons but repeat from year to year. A regional groundwater model previously developed for a portion of the San Pedro River basin, Arizona, USA, is modified to illustrate the effect that different initial conditions have on transient solutions and on capture calculations. Résumé Les "prélèvements" sont constitués par l'augmentation de la recharge et par la diminution de l'écoulement qui se produit lorsqu'un pompage est imposéà un système aquifère qui était auparavant dans un état proche de l'équilibre dynamique. Les modèles régionaux de nappe sont en général utilisés pour calculer les prélèvements dans une procédure à deux étapes. Une solution en régime permanent donne la configuration piézométrique initiale, un jeu de conditions aux limites pour la région modélisée et les données de base pour le calcul des prélèvements. Les solutions transitoires donnent les modifications globales des conditions aux limites. Lorsque des variations saisonnières sont produites en sortie du modèle, le recours à une piézométrie initiale unique et à un seul jeu de données de conditions aux limites conduit à un mauvais calcul des prélèvements. Il faut alors utiliser une condition de recharge initiale pour chaque saison. Cette approche peut être réalisée en déterminant des solutions permanentes périodiques, variantes au cours des saisons, mais se répétant d'année en année. Un modèle de nappe régional, précédemment mis au point pour une partie du bassin de la rivière San Pedro (Arizona, États-Unis), a été modifié pour illustrer l'effet de conditions initiales différentes sur des solutions transitoires et sur le calcul des prélèvements. Resumen Se define como "captura" al aumento de recarga y descenso de descarga que tiene lugar cuando se impone un bombeo en un acuífero en estado de equilibrio dinámico. Se suelen utilizar modelos regionales de agua subterránea para calcular la captura en un procedimiento que consta de dos etapas. Una solución en régimen estacionario proporciona la distribución inicial de niveles piezométricos, los flujos a través de los contornos de la región modelada y el punto de partida para el cálculo de la captura. Las soluciones transitorias proporcionan los cambios en los flujos a través de los contornos. La diferencia entre las soluciones estacionaria y transitoria da el valor de la captura. Cuando los cambios estacionales son importantes, la utilización de un único estado inicial de niveles y de flujos en los contornos da lugar a errores en el cálculo de la captura. En este caso debe usarse una condición inicial para cada una de las estaciones. Esto se puede conseguir obteniendo soluciones periódicas estacionarias, que varíen a lo largo de las estaciones, pero que se repitan año a año. Un modelo regional desarrollado previamente para el estudio de una parte de la cuenca del Río San Pedro, en Arizona (EE.UU.) se modificó para ilustrar el efecto que las distintas condiciones iniciales tienen en el cálculo de la captura.

  3. Dinámica y crecimiento de los granos de polvo en la nebulosa protoplanetaria

    NASA Astrophysics Data System (ADS)

    de La Fuente Marcos, Carlos

    2001-06-01

    En el escenario estándar de la formación planetaria, los planetesimales (cuerpos de tamaño kilométrico) crecen a partir de granos de polvo, similares a los interestelares, embebidos en un disco gaseoso denominado nebulosa protoplanetaria. Durante esta etapa, los movimientos del gas pueden tener gran influencia en la dinámica y el crecimiento de los granos de polvo, dado que el flujo kepleriano del gas frena el movimiento de los mismos haciendo que caigan hacia el Sol, y la turbulencia inhibe la inestabilidad gravitacional de la capa de polvo. Aunque se acepta que los planetesimales fueron los elementos constituyentes de los planetas, todavía se desconoce cómo se produjo la formación de los mismos. Por esta razón, en los estudios más recientes, existe un renovado interés por comprender mejor la evolución de la capa de polvo inmersa en el disco gaseoso de la Nebulosa. El gas que fluye en el disco puede engendrar estructuras carentes de simetría axial, como por ejemplo ondas espirales y vórtices, a partir de gran variedad de mecanismos de excitación e inestabilidad. En 1995, Barge y Sommeria pusieron de manifiesto que la existencia de vórtices gaseosos persistentes en la nebulosa solar tendría importantes consecuencias sobre la formación de los planetesimales y el posterior crecimiento de los planetas gigantes. La investigación desarrollada en esta Tesis analiza la relación entre el polvo y el gas debida al acoplamiento por fricción dinámica entre ambos; en concreto, se estudia el efecto del flujo medio del gas sobre la dinámica de las partículas de polvo. El primer objetivo es investigar en profundidad los procesos de captura y crecimiento de los granos de polvo dentro de un vórtice y su posible relevancia en cuanto a la formación de los planetesimales. El segundo objetivo es la exploración de los efectos de ondas espirales propagándose en el disco gaseoso sobre la dinámica y el crecimiento de las partículas. La presencia de líneas de corriente no circulares perturba significativamente el movimiento de las partículas alrededor del Sol e incrementa su vida media en la Nebulosa. El flujo medio del gas se modela de forma simple, analizándose la dinámica y el crecimiento de las partículas mediante simulaciones numéricas. Al incrementarse la vida media y la densidad superficial de las partículas sólidas, los mecanismos de confinamiento derivados de la presencia de vórtices y ondas espirales actuan sobre el material sólido de la Nebulosa (mediante agregación colisional o inestabilidades gravitacionales) de manera mucho más eficiente que la previamente considerada. Esto ofrece nuevas posibilidades para la formación de planetesimales y núcleos de planetas gigantes, y puede explicar la formación rápida de planetas extrasolares gigantes. Además, esta Tesis analiza la respuesta de las partículas, en un disco protoplanetario con un radio de 100 UA en torno a una estrella de tipo solar, al campo gravitatorio derivado de la presencia de dos estrellas compañeras ligadas en una órbita relativamente elongada (300-1600 UA). Para llevar a cabo este análisis, se han realizado una serie de simulaciones numéricas de configuraciones jerárquicas coplanares utilizando un programa FORTRAN que integra directamente las ecuaciones del movimiento con el objeto de modelar la presencia de las fuerzas gravitacionales y viscosas. El disco protoplanetario masivo se encuentra en torno a una de las componentes de la binaria. La evolución temporal del subdisco de polvo depende directamente de la naturaleza (directa o retrógrada) de la revolución relativa de la compañera estelar, y de la temperatura y la masa del disco circunestelar.