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1

Feasibility Design Report. Bauta-Toa Vaca Tunnel.  

National Technical Information Service (NTIS)

The report summarizes feasibility design studies prepared by the Bureau of Reclamation (BuRec) for the Puerto Rico Water Resources Authority (PRWRA) for Bauta-Toa Vaca Tunnel, a key feature for initial diversion of water from northward flowing streams to ...

1970-01-01

2

Expanding Allelic Diversity of Helicobacter pylori vacA  

PubMed Central

The diversity of the gene encoding the vacuolating cytotoxin (vacA) of Helicobacter pylori was analyzed in 98 isolates obtained from different geographic locations. The studies focused on variation in the previously defined s and m regions of vacA, as determined by PCR and direct sequencing. Phylogenetic analysis revealed the existence of four distinct types of s-region alleles: aside from the previously described s1a, s1b, and s2 allelic types, a novel subtype, designated s1c, was found. Subtype s1c was observed exclusively in isolates from East Asia and appears to be the major s1 allele in that part of the world. Three different allelic forms (m1, m2a, and m2b) were detected in the m region. On the basis of sequence alignments, universal PCR primers that allow effective amplification of the s and m regions from H. pylori isolates from all over the world were defined. Amplimers were subsequently analyzed by reverse hybridization onto a line probe assay (LiPA) that allows the simultaneous and highly specific hybridization of the different vacA s- and m-region alleles and tests for the presence of the cytotoxin-associated gene (cagA). This PCR-LiPA method permits rapid analysis of the vacA and cagA status of H. pylori strains for clinical and epidemiological studies and will facilitate identification of any further variations.

van Doorn, Leen-Jan; Figueiredo, Ceu; Sanna, Ricardo; Pena, Salvador; Midolo, Peter; Ng, Enders K. W.; Atherton, John C.; Blaser, Martin J.; Quint, Wim G. V.

1998-01-01

3

Significance of Helicobacter pylori vacA intermediate region genotyping-a Bulgarian study.  

PubMed

The significance of the intermediate (i) region of the Helicobacter pylori vacA gene as a virulence factor associated with the severity of gastric disease is still disputable. The aim of the present study was to evaluate the prevalence and significance of vacA i alleles alone or in combination with other vacA alleles in symptomatic Bulgarian patients and to find out possible associations between vacA i genotype and patients' disease, age, sex, and other H. pylori virulence factors. Unlike vacA s1 and m1, vacA i1 prevalence was significantly higher (75.0%) in strains from peptic ulcer patients than in strains from nonulcer patients with gastric diseases (58.6%) (P = 0.022). Less virulent vacA s1 i2 m2 strains were more prevalent in females (P = 0.03), and cagA(+) was associated with vacA i1, s1, m1, and their combinations. In conclusion, vacA i status is a better predictor for the strain virulence than other vacA alleles. PMID:22951332

Yordanov, Daniel; Boyanova, Lyudmila; Markovska, Rumyana; Gergova, Galina; Mitov, Ivan

2012-08-28

4

Molecular Evolution of the Helicobacter pylori Vacuolating Toxin Gene vacA ? †  

PubMed Central

Helicobacter pylori is a genetically diverse organism that is adapted for colonization of the human stomach. All strains contain a gene encoding a secreted, pore-forming toxin known as VacA. Genetic variation at this locus could be under strong selection as H. pylori adapts to the host immune response, colonizes new human hosts, or inhabits different host environments. Here, we analyze the molecular evolution of VacA. Phylogenetic reconstructions indicate the subdivision of VacA sequences into three main groups with distinct geographic distributions. Divergence of the three groups is principally due to positively selected sequence changes in the p55 domain, a central region required for binding of the toxin to host cells. Divergent amino acids map to surface-exposed sites in the p55 crystal structure. Comparative phylogenetic analyses of vacA sequences and housekeeping gene sequences indicate that vacA does not share the same evolutionary history as the core genome. Further, rooting the VacA tree with outgroup sequences from the close relative Helicobacter acinonychis reveals that the ancestry of VacA is different from the African origin that typifies the core genome. Finally, sequence analyses of the virulence determinant CagA reveal three main groups strikingly similar to the three groups of VacA sequences. Taken together, these results indicate that positive selection has shaped the phylogenetic structure of VacA and CagA, and each of these virulence determinants has evolved separately from the core genome.

Gangwer, Kelly A.; Shaffer, Carrie L.; Suerbaum, Sebastian; Lacy, D. Borden; Cover, Timothy L.; Bordenstein, Seth R.

2010-01-01

5

Structural analysis of the oligomeric states of Helicobacter pylori VacA toxin.  

PubMed

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

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

2012-11-20

6

The role of small molecular weight compounds to increase vacuolation induced by VacA toxin in vitro  

Microsoft Academic Search

VacA is a vacuolation protein toxin secreted by Helicobacter pylori. Many compounds have been implicated in the regulation of VacA toxin activity. In this study, regulation of cell vacuolation induced by VacA was observed with the addition of glycine, glycine hydrochloride, xylitol, and taurine by neutral red dye uptake assay using gastric human epithelial cell cultures. Glycine, xylitol, and taurine

Juan Sun; Yan Wu; Zhuang Su; Zhifang Liu; Bingzhong Su; Zhiyue Liu; Wenzhong Liu; Haixia Zhao; Tana; Bateer; Yuki Eshita; Baofeng Chi; Lingyan Zhao; Xin Fang; Wenli Hao; Siqintoya Wu; Jiang Bian; Jie Chen; Xiaohui Ouyang

2010-01-01

7

Helicobacter pylori VacA disrupts apical membrane-cytoskeletal interactions in gastric parietal cells.  

PubMed

Helicobacter pylori persistently colonize the human stomach and have been linked to atrophic gastritis and gastric carcinoma. Although it is well known that H. pylori infection can result in hypochlorhydria, the molecular mechanisms underlying this phenomenon remain poorly understood. Here we show that VacA permeabilizes the apical membrane of gastric parietal cells and induces hypochlorhydria. The functional consequences of VacA infection on parietal cell physiology were studied using freshly isolated rabbit gastric glands and cultured parietal cells. Secretory activity of parietal cells was judged by an aminopyrine uptake assay and confocal microscopic examination. VacA permeabilization induces an influx of extracellular calcium, followed by activation of calpain and subsequent proteolysis of ezrin at Met(469)-Thr(470), which results in the liberation of ezrin from the apical membrane of the parietal cells. VacA treatment inhibits acid secretion by preventing the recruitment of H,K-ATPase-containing tubulovesicles to the apical membrane of gastric parietal cells. Electron microscopic examination revealed that VacA treatment disrupts the radial arrangement of actin filaments in apical microvilli due to the loss of ezrin integrity in parietal cells. Significantly, expression of calpain-resistant ezrin restored the functional activity of parietal cells in the presence of VacA. Proteolysis of ezrin in VacA-infected parietal cells is a novel mechanism underlying H. pylori-induced inhibition of acid secretion. Our results indicate that VacA disrupts the apical membrane-cytoskeletal interactions in gastric parietal cells and thereby causes hypochlorhydria. PMID:18625712

Wang, Fengsong; Xia, Peng; Wu, Fang; Wang, Dongmei; Wang, Wei; Ward, Tarsha; Liu, Ya; Aikhionbare, Felix; Guo, Zhen; Powell, Michael; Liu, Bingya; Bi, Feng; Shaw, Andrew; Zhu, Zhenggang; Elmoselhi, Adel; Fan, Daiming; Cover, Timothy L; Ding, Xia; Yao, Xuebiao

2008-07-14

8

A Novel Method for Genotyping the Helicobacter pylori vacA Intermediate Region Directly in Gastric Biopsy Specimens  

PubMed Central

The present report describes a novel method for genotyping the virulence-associated vacA intermediate (i) region of Helicobacter pylori in archive material. vacA i-region genotypes as determined by the novel method were completely concordant with those of sequence analysis and with those of functional vacuolation activity. The method was further validated directly in gastric biopsy specimens of 386 H. pylori-positive cases, and effective characterization of the vacA i region was obtained in 191 of 192 (99.5%) frozen and in 186 of 194 (95.9%) formalin-fixed paraffin-embedded gastric biopsy specimens, respectively. The genotyping method was next used to address the relationship between the vacA genotypes and the cagA status. The vacA i1 genotype was associated with vacA s1 (where s indicates signal region), vacA m1 (where m indicates middle region), and cagA-positive genotypes (P < 0.0001), while the vacA i2 genotype was closely related with vacA s2, vacA m2, and cagA-negative genotypes (P < 0.0001). The relationship between H. pylori vacA i-region genotypes and gastric disease development was subsequently evaluated in the Portuguese population. Patients infected with vacA i1 strains showed an increased risk for gastric atrophy and for gastric carcinoma, with odds ratios of 8.0 (95% confidence interval [CI], 2.3 to 27) and of 22 (95% CI, 7.9 to 63), respectively. Taken together, the results show that this novel H. pylori vacA i-region genotyping method can be applied directly to archive material, providing a fast evaluation of strain virulence determinants without the need of culture. The results further emphasize that the characterization of the vacA i region may be useful to identify patients at higher risk of gastric carcinoma development.

Ferreira, Rui M.; Machado, Jose C.; Letley, Darren; Atherton, John C.; Pardo, Maria L.; Gonzalez, Carlos A.; Carneiro, Fatima

2012-01-01

9

Remodeling the host environment: modulation of the gastric epithelium by the Helicobacter pylori vacuolating toxin (VacA)  

PubMed Central

Virulence mechanisms underlying Helicobacter pylori persistence and disease remain poorly understood, in part, because the factors underlying disease risk are multifactorial and complex. Among the bacterial factors that contribute to the cumulative pathophysiology associated with H. pylori infections, the vacuolating cytotoxin (VacA) is one of the most important. Analogous to a number of H. pylori genes, the vacA gene exhibits allelic mosaicism, and human epidemiological studies have revealed that several families of toxin alleles are predictive of more severe disease. Animal model studies suggest that VacA may contribute to pathogenesis in several ways. VacA functions as an intracellular-acting protein exotoxin. However, VacA does not fit the current prototype of AB intracellular-acting bacterial toxins, which elaborate modulatory effects through the action of an enzymatic domain translocated inside host cells. Rather, VacA may represent an alternative prototype for AB intracellular acting toxins that modulate cellular homeostasis by forming ion-conducting intracellular membrane channels. Although VacA seems to form channels in several different membranes, one of the most important target sites is the mitochondrial inner membrane. VacA apparently take advantage of an unusual intracellular trafficking pathway to mitochondria, where the toxin is imported and depolarizes the inner membrane to disrupt mitochondrial dynamics and cellular energy homeostasis as a mechanism for engaging the apoptotic machinery within host cells. VacA remodeling of the gastric environment appears to be fine-tuned through the action of the Type IV effector protein CagA which, in part, limits the cytotoxic effects of VacA in cells colonized by H. pylori.

Kim, Ik-Jung; Blanke, Steven R.

2012-01-01

10

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

PubMed Central

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.

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

2012-01-01

11

vacA Genotypes and Genetic Diversity in Clinical Isolates of Helicobacter pylori  

PubMed Central

Genetic diversity in Helicobacter pylori strains may affect the function and antigenicity of virulence factors associated with bacterial infection and, ultimately, disease outcome. In this study, DNA diversity of H. pylori isolates was examined by analysis of vacA genotypes and by restriction fragment length polymorphism (RFLP) analysis of H. pylori-associated genes (vacA, cagA, flaA, ureAB, and ureCD). Thirty-seven H. pylori isolates from 26 patients were successfully classified into distinct vacA allelic genotypes. The signal sequence allele s1 (31 of 37) predominated over the s2 allele (6 of 37) and was significantly associated with the occurrence (past or present) of gastric ulcers. A novel midregion allele, designated as m3, has been identified in two H. pylori isolates which could not be typed with midregion allele m1- or m2-specific primers. Additionally, significant nucleotide diversity yielding different amino acid sequences was demonstrated by DNA sequencing of vacA fragments from clinical isolates of H. pylori. Furthermore, RFLP analysis of 45 H. pylori isolates (including 15 paired isolates) obtained from antrum and corpus biopsy specimens from 30 individual patients showed remarkably high interhost diversity (one patient, one H. pylori strain) and intrahost identity in gene sequences coding for VacA, CagA, flagellin, and urease. Only in a single patient was a minor genotypic variation at different anatomic sites within the stomach identified. These data warrant the detailed analysis of the effect of genetic diversity on the function and antigenicity of H. pylori-associated virulence factors.

Han, Shan-Rui; Schreiber, Hans-Joachim; Bhakdi, Sucharit; Loos, Michael; Maeurer, Markus J.

1998-01-01

12

Clinical and pathological importance of heterogeneity in vacA, the vacuolating cytotoxin gene of Helicobacter pylori  

Microsoft Academic Search

BACKGROUND & AIMS: vacA encodes the vacuolating cytotoxin of Helicobacter pylori and exhibits marked variation in signal sequence and midgene coding regions. The implications for gastroduodenal pathology are unknown. The aim of this study was to define the association of vacA genotype with gastric inflammation and injury, in vitro cytotoxin activity, and peptic ulceration. METHODS: Sixty-one consecutive dyspeptic patients underwent

JC Atherton; RM Peek; KT Tham; MJ Blaser

1997-01-01

13

vacA Genotypes of Helicobacter pylori in Relation to cagA Status and Clinical Outcomes in Iranian Populations  

PubMed Central

SUMMARY Mosaicism in vacA alleles with two distinct families of vacA signal sequences (s1 and s2) and two distinct families of middle region alleles (m1 and m2) has been reported. Research suggests that the vacA s1 genotype is closely associated with duodenal ulcer disease and with high cytotoxin production. The aims of this study were to evaluate the role of vacA genotyping with respect to gastric inflammation and injury, and clinical presentation in Iranian populations. Genomic DNA of biopsy specimens from patients with gastritis, peptic ulcer disease (PUD), or gastric cancer (GC) were characterized based on ureC (glmM), cagA, and vacA genotyping by using polymerase chain reaction. Of 167 patients including 33 with PUDs, 129 with non-ulcer dyspepsia (NUD), and 5 with GC, 96 (57.5%) cases were infected by Helicobacter pylori. Among these patients, H. pylori were isolated from 19 (57.7%) PUD patients, 74 (68.7%) NUD patients, and 3 (60%) GC patients. The cagA was detected in 76% of H. pylori-positive cases. The vacA s1-m2 genotype was the most prevalent in 7/19 PUD (37%) and 30/74 NUD (40.5%) patients with H. pylori infection. The prevalence of vacA s2-m1 (8%) was high in Iranian isolates. A significant association was not found between H. pylori genotypes and clinical outcomes. The vacA genotypes and cagA status were not useful markers for gastroduodenal diseases in Tehran, Iran.

Jafari, Fereshteh; Shokrzadeh, Leila; Dabiri, Hossein; Baghaei, Kaveh; Yamaoka, Yoshio; Zojaji, Homayon; Haghazali, Mehrdad; Molaei, Mahsa; Zali, Mohammad Reza

2013-01-01

14

The association of vacA genotypes and Helicobacter pylori -related gastroduodenal diseases in the Middle East  

Microsoft Academic Search

The variations in the three regions of the Helicobacter pylori vacA gene, the signal (s1 and s2), intermediate (i1 and i2) and middle regions (m1 and m2), are known to cause the differences\\u000a in vacuolating activities. However, it was unclear whether these vacA genotypes are associated with the development of gastric cancer and peptic ulcer in the Middle East. The

M. Sugimoto; M. R. Zali; Y. Yamaoka

2009-01-01

15

Inhibitory Effects of Anthocyanins on Secretion of Helicobacter pylori CagA and VacA Toxins  

PubMed Central

Anthocyanins have been studied as potential antimicrobial agents against Helicobacter pylori. We investigated whether the biosynthesis and secretion of cytotoxin-associated protein A (CagA) and vacuolating cytotoxin A (VacA) could be suppressed by anthocyanin treatment in vitro. H. pylori reference strain 60190 (CagA+/VacA+) was used in this study to investigate the inhibitory effects of anthocyanins; cyanidin 3-O-glucoside (C3G), peonidin 3-O-glucoside (Peo3G), pelargonidin 3-O-glucoside (Pel3G), and malvidin 3-O-glucoside (M3G) on expression and secretion of H. pylori toxins. Anthocyanins were added to bacterial cultures and Western blotting was used to determine secretion of CagA and VacA. Among them, we found that C3G inhibited secretion of CagA and VacA resulting in intracellular accumulation of CagA and VacA. C3G had no effect on cagA and vacA expression but suppressed secA transcription. As SecA is involved in translocation of bacterial proteins, the down-regulation of secA expression by C3G offers a mechanistic explanation for the inhibition of toxin secretion. To our knowledge, this is the first report suggesting that C3G inhibits secretion of the H. pylori toxins CagA and VacA via suppression of secA transcription.

Kim, Sa-Hyun; Park, Min; Woo, Hyunjun; Tharmalingam, Nagendran; Lee, Gyusang; Rhee, Ki-Jong; Eom, Yong Bin; Han, Sang Ik; Seo, Woo Duck; Kim, Jong Bae

2012-01-01

16

Helicobacter pylori VacA Toxin Inhibits Human Immunodeficiency Virus Infection of Primary Human T Cells  

Microsoft Academic Search

Human CD4 T cells are major targets for human immunodeficiency virus (HIV) infection. Resting T cells are resistant to HIV infection unless activated through the T-cell receptor (TCR) or by cytokine signals. How T-cell signaling promotes susceptibility of T cells to HIV infection remains poorly understood. Here we demonstrate that the VacA toxin produced by Helicobacter pylori can inhibit HIV

Kyra Oswald-Richter; Victor J. Torres; Mark S. Sundrud; Scott E. VanCompernolle; Derya Unutmaz

2006-01-01

17

SOBRE O VALOR ECONÔMICO DO SISTEMA DE IDENTIFICAÇÃO ANIMAL DOS EUA (NAIS): NOTÍCIAS A RESPEITO DO MAU DA VACA LOUCA AFETAM O CONSUMO DE CARNES?  

Microsoft Academic Search

Esse artigo investiga os efeitos de notícias a respeito do mau da vaca louca ou BSE sobre o consumo das carnes bovina, suína e de aves nos EUA. Presume-se que o sistema nacional de identificação animal (NAIS) poderia em tese atenuar a percepção de risco dos consumidores sobre contrair o mau da vaca louca ao consumir carnes. Sistemas de equações

Moises de Andrade Resende Filho; Brian L. Buhr

2008-01-01

18

Helicobacter pylori oipA genetic diversity and its associations with both disease and cagA, vacA s, m, and i alleles among Bulgarian patients.  

PubMed

Prevalence of outer inflammatory protein (oipA) gene functional status in Helicobacter pylori strains from Southeastern Europe is still unclear. H. pylori strains from 70 symptomatic patients were polymerase chain reaction (PCR) assessed for cagA and vacA types, and oipA gene functional status was evaluated by PCR and sequencing. Our results demonstrated a high prevalence of strains with oipA status "on" genes (81%) and strong association between them and peptic ulcers, cagA, and vacA s1 and s1/m1 genotypes, regardless of the patient gender, place of residence, and age. Importantly, most vacA i1 strains (93%) harbored oipA status "on" versus only 57% of those with vacA i2 type. The vacA i1 genotype was less frequent (66%) than both cagA and vacA s1 types. The virulent strains with cagA(+) and vacA s1, m1, and i1 were detected in 35% as a predominant genotype and almost all (96%) of these strains harbored oipA status "on". In conclusion, the high prevalence of in-frame oipA gene strains (81%), associated with peptic ulcers and cagA(+), vacA s1, m1, m2, and, importantly, i1 genotypes, indicates a strong synergistic activity of H. pylori virulence factors. PMID:21937185

Markovska, Rumyana; Boyanova, Lyudmila; Yordanov, Daniel; Gergova, Galina; Mitov, Ivan

2011-09-19

19

Polymorphism in the Helicobacter pylori CagA and VacA toxins and disease.  

PubMed

Half of the world's population is infected with Helicobacter pylori and approximately 20% of infected individuals develop overt clinical disease such as ulcers and stomach cancer. Paradoxically, despite its classification as a class I carcinogen, H. pylori has been shown to be protective against development of asthma, allergy, and esophageal disease. Given these conflicting roles for H. pylori, researchers are attempting to define the environmental, host, and pathogen interactions that ultimately result in severe disease in some individuals. From the bacterial perspective, the toxins, CagA and VacA, have each been shown to be polymorphic and to contribute to disease in an allele-dependent manner. Based on the notable advances that have recently been made in the CagA field, herein we review recent studies that have begun to shed light on the role of CagA polymorphism in H. pylori disease. Moreover, we discuss the potential interaction of CagA and VacA as a mediator of gastric disease. PMID:23380646

Bridge, Dacie R; Merrell, D Scott

2013-02-04

20

Clustering of Helicobacter pylori VacA in Lipid Rafts, Mediated by Its Receptor, Receptor-Like Protein Tyrosine Phosphatase  , Is Required for Intoxication in AZ-521 Cells  

Microsoft Academic Search

Helicobacter pylori vacuolating cytotoxin, VacA, induces multiple effects on epithelial cells through different cellular events: one involves pore formation, leading to vacuolation, mitochondrial damage, and apoptosis, and the second involves cell signaling, resulting in stimulation of proinflammatory responses and cell detachment. Our recent data demonstrated that VacA uses receptor-like protein tyrosine phosphatase (RPTP )a s a receptor, of which five

Masaaki Nakayama; Jyunzo Hisatsune; Eiki Yamasaki; Yoshito Nishi; Akihiro Wada; Hisao Kurazono; Jan Sap; Kinnosuke Yahiro; Joel Moss; Toshiya Hirayama

2006-01-01

21

The Cell-Specific Phenotype of the Polymorphic vacA Midregion Is Independent of the Appearance of the Cell Surface Receptor Protein Tyrosine Phosphatase  

Microsoft Academic Search

There are two alleles, m1 and m2, of the midregion of the vacuolating cytotoxin gene (vacA )o fHelicobacter pylori which code for toxins with different cell specificities. Here we describe the construction of five chimeric strains in which regions of vacA were exchanged between the two genotypes. By analyzing the toxicity of these strains for HeLa and RK13 cells we

David A. G. Skibinski; Christophe Genisset; Silvia Barone; John L. Telford

2006-01-01

22

Reconstitution of Helicobacter pylori VacA toxin from purified components  

PubMed Central

Helicobacter pylori VacA is a pore-forming toxin that causes multiple alterations in human cells and contributes to the pathogenesis of peptic ulcer disease and gastric cancer. The toxin is secreted by H. pylori as an 88 kDa monomer (p88) consisting of two domains (p33 and p55). While an X-ray crystal structure for p55 exists and p88 oligomers have been visualized by cryo-electron microscopy, a detailed analysis of p33 has been hindered by an inability to purify this domain in an active form. In this study, we expressed and purified a recombinant form of p33 under denaturing conditions and optimized conditions for the refolding of soluble protein. We show that refolded p33 can be added to purified p55 in trans to cause vacuolation of HeLa cells and inhibition of IL-2 production by Jurkat cells, effects identical to those produced by the p88 toxin from H. pylori. The p33 protein markedly enhances the cell-binding properties of p55. Size exclusion chromatography experiments suggest that p33 and p55 assemble into a complex consistent with the size of a p88 monomer. Electron microscopy of these p33/p55 complexes reveals small rod-shaped structures that can convert to oligomeric flower-shaped structures in the presence of detergent. We propose that the oligomerization observed in these experiments mimics the process by which VacA oligomerizes when in contact with membranes of host cells.

Gonzalez-Rivera, Christian; Gangwer, Kelly A.; McClain, Mark S.; Eli, Ilyas M.; Chambers, Melissa G.; Ohi, Melanie D.; Lacy, D. Borden; Cover, Timothy L.

2010-01-01

23

Clinical relevance of the cagA, vacA, and iceA status of Helicobacter pylori  

Microsoft Academic Search

Background & Aims: Clinical outcome of Helicobacter pylori infection may be associated with specific virulence-associated bacterial genotypes. The aim of this study was to assess the relationships between H. pylori cagA, vacA, and iceA status and severity of disease. Methods: Gastric biopsy specimens from 94 patients in The Netherlands were analyzed by polymerase chain reaction and reverse hybridization. Results:cagA was

Céu Figueiredo; Ricardo Sanna; Anton Plaisier; Peter Schneeberger; Wink de Boer; Wim Quint

1998-01-01

24

Role of Helicobacter pylori cagA EPIYA motif and vacA genotypes for the development of gastrointestinal diseases in Southeast Asian countries: a meta-analysis  

PubMed Central

Background Infection with cagA-positive, cagA EPIYA motif ABD type, and vacA s1, m1, and i1 genotype strains of Helicobacter pylori is associated with an exacerbated inflammatory response and increased risk of gastroduodenal diseases. However, it is unclear whether the prevalence and virulence factor genotypes found in Southeast Asia are similar to those in Western countries. Here, we examined the cagA status and prevalence of cagA EPIYA motifs and vacA genotypes among H. pylori strains found in Southeast Asia and examined their association with gastroduodenal disease. Methods To determine the cagA status, cagA EPIYA motifs, and vacA genotypes of H. pylori, we conducted meta-analyses of 13 previous reports for 1,281?H. pylori strains detected from several Southeast Asian countries. Results The respective frequencies of cagA-positive and vacA s1, m1, and i1 genotypes among examined subjects were 93% (1,056/1,133), 98% (1,010/1,033), 58% (581/1,009), and 96% (248/259), respectively. Stratification showed significant variation in the frequencies of cagA status and vacA genotypes among countries and the individual races residing within each respective country. The frequency of the vacA m-region genotype in patients infected with East Asian-type strains differed significantly between the northern and southern areas of Vietnam (p?vacA m1 type or cagA-positive strains was associated with an increased risk of peptic ulcer disease (odds ratio: 1.46, 95%CI: 1.01-2.12, p?=?0.046 and 2.83, 1.50-5.34, p?=?0.001, respectively) in the examined Southeast Asian populations. Conclusions Both Western- and East Asian-type strains of H. pylori are found in Southeast Asia and are predominantly cagA-positive and vacA s1 type. In Southeast Asia, patients infected with vacA m1 type or cagA-positive strains have an increased risk of peptic ulcer disease. Thus, testing for this genotype and the presence of cagA may have clinical usefulness.

2012-01-01

25

Evaluation of clarithromycin resistance and cagA and vacA genotyping of Helicobacter pylori strains from the west of Ireland using line probe assays.  

PubMed

The prevalence of clarithromycin resistance-associated mutations, the cytotoxin-associated gene (cagA), and the various vacuolating cytotoxin (vacA) genotypes was determined in 50 gastric biopsy specimens from Helicobacter pylori-infected patients, using line probe assays. The clarithromycin resistance-associated mutation A2143G was detected in H. pylori strains from 26% of the specimens, which suggested that the high rate of H. pylori treatment failure in Ireland may be partly attributable to the presence of these mutations. All strains examined carried the vacA s1 genotype, and 76% were cagA positive. Of these 50 specimens, 13 (26%) carried H. pylori strains with vacA midregion genotype m1, 29 (58%) carried strains that were m2, 1 (2%) was infected by a strain that was positive for both m1 and m2, and 7 (14%) carried strains that could not be typed. PMID:11326028

Ryan, K A; van Doorn, L J; Moran, A P; Glennon, M; Smith, T; Maher, M

2001-05-01

26

81Kr-Kr age and multiple cosmic-ray exposure history of the Vaca Muerta mesosiderite  

NASA Astrophysics Data System (ADS)

Noble gas isotopic compositions were measured for a eucritic pebble and bulk material of a silicate-metal mixture from the Vaca Muerta mesosiderite as well as pyroxene and plagioclase separated from the eucritic pebble by total melting and stepwise heating methods. Trapped noble gases were degassed completely by a high-temperature thermal event, probably at the formation of the Vaca Muerta parent body (VMPB). The presence of fissiogenic Xe isotopes from extinct 244Pu in the bulk samples might be a result of rapid cooling from an early high-temperature metamorphism. High concentrations of cosmogenic noble gases enabled us to determine precise isotopic ratios of cosmogenic Kr and Xe. Spallogenic Ne from Na and unique Ar isotopic compositions were observed. The 81Kr-Kr exposure age of 168 ± 8 Myr for the silicate pebble is distinctly longer than the age of 139 ± 8 Myr for the bulk samples. The precursor of the pebble had been irradiated on the surface of the VMPB for more than 60 Myr (first stage irradiation), with subsequent incorporation into bulk materials approximately 4 Gyr ago. The Vaca Muerta meteorite was excavated from the VMPB 140 Myr ago (second stage irradiation). Relative diffusion rates among the cosmogenic Ar, Kr, and Xe based on data obtained by stepwise heating indicate that Kr and Xe can be partially retained in pyroxene and plagioclase under the condition that resets the K-Ar system. This result supports the presence of fission Xe and of excess concentration of cosmogenic Kr, which could have survived the thermal event approximately 3.8 Gyr ago.

Bajo, Ken-Ichi; Nagao, Keisuke

2011-04-01

27

Helicobacter pylori VacA Toxin/Subunit p34: Targeting of an Anion Channel to the Inner Mitochondrial Membrane  

PubMed Central

The vacuolating toxin VacA, released by Helicobacter pylori, is an important virulence factor in the pathogenesis of gastritis and gastroduodenal ulcers. VacA contains two subunits: The p58 subunit mediates entry into target cells, and the p34 subunit mediates targeting to mitochondria and is essential for toxicity. In this study we found that targeting to mitochondria is dependent on a unique signal sequence of 32 uncharged amino acid residues at the p34 N-terminus. Mitochondrial import of p34 is mediated by the import receptor Tom20 and the import channel of the outer membrane TOM complex, leading to insertion of p34 into the mitochondrial inner membrane. p34 assembles in homo-hexamers of extraordinary high stability. CD spectra of the purified protein indicate a content of >40% ?-strands, similar to pore-forming ?-barrel proteins. p34 forms an anion channel with a conductivity of about 12 pS in 1.5 M KCl buffer. Oligomerization and channel formation are independent both of the 32 uncharged N-terminal residues and of the p58 subunit of the toxin. The conductivity is efficiently blocked by 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), a reagent known to inhibit VacA-mediated apoptosis. We conclude that p34 essentially acts as a small pore-forming toxin, targeted to the mitochondrial inner membrane by a special hydrophobic N-terminal signal.

Harsman, Anke; Papatheodorou, Panagiotis; Reljic, Boris; Dian-Lothrop, Elke A.; Galmiche, Antoine; Kepp, Oliver; Becker, Lars; Gunnewig, Kathrin; Wagner, Richard; Rassow, Joachim

2010-01-01

28

A Tale of Two Toxins: Helicobacter Pylori CagA and VacA Modulate Host Pathways that Impact Disease  

PubMed Central

Helicobacter pylori is a pathogenic bacterium that colonizes more than 50% of the world's population, which leads to a tremendous medical burden. H. pylori infection is associated with such varied diseases as gastritis, peptic ulcers, and two forms of gastric cancer: gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. This association represents a novel paradigm for cancer development; H. pylori is currently the only bacterium to be recognized as a carcinogen. Therefore, a significant amount of research has been conducted to identify the bacterial factors and the deregulated host cell pathways that are responsible for the progression to more severe disease states. Two of the virulence factors that have been implicated in this process are cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA), which are cytotoxins that are injected and secreted by H. pylori, respectively. Both of these virulence factors are polymorphic and affect a multitude of host cellular pathways. These combined facts could easily contribute to differences in disease severity across the population as various CagA and VacA alleles differentially target some pathways. Herein we highlight the diverse types of cellular pathways and processes targeted by these important toxins.

Jones, Kathleen R.; Whitmire, Jeannette M.; Merrell, D. Scott

2010-01-01

29

Prevalence of Helicobacter pylori vacA, cagA, iceA and oipA genotypes in Tunisian patients  

PubMed Central

Background Distinct virulence factors of H. pylori have been described: the vaculating cytotoxin (vacA), the cytotoxin associated gene (cagA), the induced by contact with epithelium factor Antigen (iceA gene) and the outer membrane protein oipA. In Tunisia, there are no data regarding the pattern of H. pylori genotypes; therefore, this prospective and multicentre study was the first to be done in Tunisia and aimed to investigate the prevalence of the vacA, cagA, iceA and oipA genotypes of H. pylori isolates from Tunisian patients with peptic ulceration, gastric cancer, MALT lymphoma and gastritis. Methods H. pylori was cultured from endoscopic biopsies obtained from 281 Tunisian patients. The vacA alleles, cagA, iceA and oipA genotypes were determined by PCR. Results The vacA s1m1, s1m2 and s2m2 were respectively found in 10.7%, 12.5% and 45.6% of strains. The s2m1 genotype was not detected in our study. The cagA was found in 61.6% of isolates. The iceA1 and the iceA2 genotypes were respectively isolated in 60.2% and in 16% of strains. The oipA genotype was detected in 90.8% of strains. Considering the vacA and iceA genotypes, the presence of multiple H. pylori strains in a single biopsy specimen was found respectively in 31.4% and 23.8%. The comparison between strains isolated from antrum and fundus showed that Tunisian patients were infected with two or more strains of different cagA, vacA, iceA and oipA genotypes and the discordance was respectively in 9.6%, 4.6%, 8.9% and 8.5% of strains. Conclusion Our results showed that in 46% (131 strains among 281), the H. pylori strains were highly virulent in relation of the three or four virulent factors they could carry. These finding were described before in the literature. Tunisian patients were colonized by one or multiple strains of H. pylori in the same time in relation of presence of vacA m1/m2 and iceA1/iceA2 in the same biopsy. The discordance between strains isolated from antrum and fundus was high, and it is in favour of multicolonization.

2010-01-01

30

Molecular and cellular mechanisms of action of the vacuolating cytotoxin (VacA) and neutrophil-activating protein (HP-NAP) virulence factors of Helicobacter pylori  

Microsoft Academic Search

Helicobacter pylori has elaborated a unique set of virulence factors that allow it to colonise the stomach wall. These factors include urease, helicoidal shape, flagella and adhesion molecules. Here we discuss the molecular characteristics and mechanisms of action of the vacuolating cytotoxin, VacA, and the neutrophil-activating protein, HP-NAP. Their activities are discussed in terms of tissue alterations, which promote the

Cesare Montecucco; Marina de Bernard

2003-01-01

31

Relationship between Helicobacter pylori iceA, cagA, and vacA Status and Clinical Outcome: Studies in Four Different Countries  

Microsoft Academic Search

There is continuing interest in identifying Helicobacter pylori virulence factors that might predict the risk for symptomatic clinical outcomes. It has been proposed that iceA and cagA genes are such markers and can identify patients with peptic ulcers. We compared H. pylori isolates from four countries, looking at the cagA and vacA genotypes, iceA alleles, and presentation of the infection.

YOSHIO YAMAOKA; TADASHI KODAMA; OSCAR GUTIERREZ; JONG G. KIM; KEI KASHIMA; DAVID Y. GRAHAM

1999-01-01

32

Distinct Diversity of vacA, cagA, and cagE Genes of Helicobacter pylori Associated with Peptic Ulcer in Japan  

Microsoft Academic Search

Colonization of the stomach mucosa by Helicobacter pylori is a major cause of acute and chronic gastric pathologies in humans. Several H. pylori virulence genes that may play a role in its pathogenicity have been identified. The most important determinants are vacA and cagA in the cag pathogenicity island (cagPAI) genes. In the present study, to consider the association of

Shiho Yamazaki; Akiyo Yamakawa; Tomoyuki Okuda; Masahiro Ohtani; Hiroyuki Suto; Yoshiyuki Ito; Yukinao Yamazaki; Yoshihide Keida; Hideaki Higashi; Masanori Hatakeyama; Takeshi Azuma

2005-01-01

33

Helicobacter pylori Counteracts the Apoptotic Action of Its VacA Toxin by Injecting the CagA Protein into Gastric Epithelial Cells  

Microsoft Academic Search

Infection with Helicobacter pylori is responsible for gastritis and gastroduodenal ulcers but is also a high risk factor for the development of gastric adenocarcinoma and lymphoma. The most pathogenic H. pylori strains (i.e., the so-called type I strains) associate the CagA virulence protein with an active VacA cytotoxin but the rationale for this association is unknown. CagA, directly injected by

Amanda Oldani; Mireille Cormont; Veronique Hofman; Valentina Chiozzi; Olivier Oregioni; Alexandra Canonici; Anna Sciullo; Patrizia Sommi; Alessia Fabbri; Vittorio Ricci; Patrice Boquet

2009-01-01

34

Extracellular pH Modulates Helicobacter pylori-Induced Vacuolation and VacA Toxin Internalization in Human Gastric Epithelial Cells  

Microsoft Academic Search

In this study we investigated whether an acidic extracellular pH may inhibit H. pylori-induced internalization of bacterial virulence factors by gastric epithelium, thus preventing ingestion of potentially dangerous luminal contents and resulting cellular damage. The interaction of H. pylori VacA toxin and ammonia (produced by H. pylori urease) with partly polarized gastric MKN 28 cells in culture was investigated at

Vittorio Ricci; Patrizia Sommi; Roberto Fiocca; Vittorio Necchi; Marco Romano; Enrico Solcia

2002-01-01

35

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

Microsoft Academic Search

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

Dinorah N Martínez-Carrillo; Elvira Garza-González; Reyes Betancourt-Linares; Trinidad Mónico-Manzano; Cuauhtémoc Antúnez-Rivera; Adolfo Román-Román; Eugenia Flores-Alfaro; Berenice Illades-Aguiar; Gloria Fernández-Tilapa

2010-01-01

36

Association of peptic ulcer with increased expression of Lewis antigens but not cagA, iceA, and vacA in Helicobacter pylori isolates in an Asian population  

PubMed Central

BACKGROUND—Studies in Western populations suggest that cagA, iceA, and vacA gene status in Helicobacter pylori isolates is associated with increased virulence and peptic ulcer disease.?AIM—To investigate the relationship between peptic ulcer and expression of Lewis (Le) antigens as well as cagA, iceA, and vacA in H pylori isolates in Singapore.?METHODS—Expression of Le antigens in H pylori isolates obtained from patients with dyspepsia was measured by enzyme linked immunosorbent assay. The cagA, iceA, and vacA status was determined by polymerase chain reaction.?RESULTS—Of 108 H pylori isolates, 103 (95.4%) expressed Lex and/or Ley, while Lea and Leb were expressed in 23 (21.3%) and 47 (43.5%) isolates, respectively. Expression of two or more Le antigens (Lex, Ley, Lea, or Leb) was significantly higher in H pylori isolated from ulcer patients than in non-ulcer patients (89.6% v 73.2%, p=0.035). There were no significant differences in the prevalence of cagA or iceA1 in H pylori isolates from peptic ulcer and non-ulcer patients (86.6% v 90.2% for cagA; 70.1% v 68.3% for iceA1), and no association of peptic ulcer with any specific vacA genotype.?CONCLUSIONS—The present study indicates that peptic ulcer disease is associated with increased expression of Lewis antigens but not cagA, iceA, or vacA genotype in H pylori isolates in our population. This suggests that cagA, iceA, and vacA are not universal virulence markers, and that host-pathogen interactions are important in determining clinical outcome.???Keywords: Lewis blood group antigens; cagA; iceA; vacA; Helicobacter pylori; peptic ulcer

Zheng, P; Hua, J; Yeoh, K; Ho, B

2000-01-01

37

Helicobacter pylori VacA suppresses Lactobacillus acidophilus-induced interferon beta signaling in macrophages via alterations in the endocytic pathway.  

PubMed

Helicobacter pylori causes chronic gastritis and avoids elimination by the immune system of the infected host. The commensal bacterium Lactobacillus acidophilus has been suggested to exert beneficial effects as a supplement during H. pylori eradication therapy. In the present study, we applied whole-genome microarray analysis to compare the immune responses induced in murine bone marrow-derived macrophages (BMDMs) stimulated with L. acidophilus, H. pylori, or both bacteria in combination. While L. acidophilus induced a Th1-polarizing response characterized by high expression of interferon beta (IFN-?) and interleukin 12 (IL-12), H. pylori strongly induced the innate cytokines IL-1? and IL-1?. In BMDMs prestimulated with L. acidophilus, H. pylori blocked the expression of L. acidophilus-induced IFN-? and IL-12 and suppressed the expression of key regulators of the Rho, Rac, and Cdc42 GTPases. The inhibition of L. acidophilus-induced IFN-? was independent of H. pylori viability and the virulence factor CagPAI; however, a vacuolating cytotoxin (vacA) mutant was unable to block IFN-?. Confocal microscopy demonstrated that the addition of H. pylori to L. acidophilus-stimulated BMDMs redirects intracellular processing, leading to an accumulation of L. acidophilus in the endosomal and lysosomal compartments. Thus, our findings indicate that H. pylori inhibits the development of a strong Th1-polarizing response in BMDMs stimulated with L. acidophilus by blocking the production of IFN-? in a VacA-dependent manner. We suggest that this abrogation is caused by a redirection of the endocytotic pathway in the processing of L. acidophilus. IMPORTANCE Approximately half of the world's population is infected with Helicobacter pylori. The factors that allow this pathogen to persist in the stomach and cause chronic infections have not yet been fully elucidated. In particular, how H. pylori avoids killing by macrophages, one of the main types of immune cell underlying the epithelium, remains elusive. Here we have shown that the H. pylori virulence factor VacA plays a key role by blocking the activation of innate cytokines induced by the probiotic Lactobacillus acidophilus in macrophages and suppresses the expression of key regulators required for the organization and dynamics of the intracellular cytoskeleton. Our results identify potential targets for the treatment of H. pylori infection and vaccination, since specific inhibition of the toxin VacA possibly allows the activation of an efficient immune response and thereby eradication of H. pylori in the host. PMID:23760466

Weiss, Gudrun; Forster, Sam; Irving, Aaron; Tate, Michelle; Ferrero, Richard L; Hertzog, Paul; Frøkiær, Hanne; Kaparakis-Liaskos, Maria

2013-06-11

38

PCR-Based Restriction Pattern Typing of the vacA Gene Provides Evidence for a Homogeneous Group among Helicobacter pylori Strains Associated with Peptic Ulcer Disease  

PubMed Central

The results of PCR-based molecular typing of Helicobacter pylori strains by restriction fragment length polymorphism analysis of a 1,161-bp nucleotide sequence of the midregion of the vacA gene are reported. A total of 48 H. pylori strains isolated from gastric biopsy specimens obtained from 18 patients with peptic ulcer dyspepsia, 15 patients with nonulcer dyspepsia, and 15 asymptomatic H. pylori-infected subjects were studied. Highly heterogeneous restriction patterns were obtained by digestion of PCR products with SauII, BglII, and HhaI, whereas HaeIII digestion resulted in a strictly homogeneous profile for H. pylori strains isolated from 14 of 18 (77.7%) patients with peptic ulcer dyspepsia, but a strictly homogeneous profile was found for strains from only 8 of 15 (53.3%) patients with nonulcer dyspepsia (P = 0.163) and 5 of 15 (33.3%) asymptomatic H. pylori-infected subjects (P = 0.014). A potentially important aspect of the results obtained is the clinical relevance, since a single restriction pattern seems to be able to identify the majority of H. pylori strains associated with peptic ulcer disease.

Donati, Manuela; Storni, Elisa; D'Apote, Lucia; Moreno, Sandra; Tucci, Antonio; Poli, Loris; Cevenini, Roberto

1999-01-01

39

Helicobacter pylori VacA Suppresses Lactobacillus acidophilus-Induced Interferon Beta Signaling in Macrophages via Alterations in the Endocytic Pathway  

PubMed Central

ABSTRACT Helicobacter pylori causes chronic gastritis and avoids elimination by the immune system of the infected host. The commensal bacterium Lactobacillus acidophilus has been suggested to exert beneficial effects as a supplement during H. pylori eradication therapy. In the present study, we applied whole-genome microarray analysis to compare the immune responses induced in murine bone marrow-derived macrophages (BMDMs) stimulated with L. acidophilus, H. pylori, or both bacteria in combination. While L. acidophilus induced a Th1-polarizing response characterized by high expression of interferon beta (IFN-?) and interleukin 12 (IL-12), H. pylori strongly induced the innate cytokines IL-1? and IL-1?. In BMDMs prestimulated with L. acidophilus, H. pylori blocked the expression of L. acidophilus-induced IFN-? and IL-12 and suppressed the expression of key regulators of the Rho, Rac, and Cdc42 GTPases. The inhibition of L. acidophilus-induced IFN-? was independent of H. pylori viability and the virulence factor CagPAI; however, a vacuolating cytotoxin (vacA) mutant was unable to block IFN-?. Confocal microscopy demonstrated that the addition of H. pylori to L. acidophilus-stimulated BMDMs redirects intracellular processing, leading to an accumulation of L. acidophilus in the endosomal and lysosomal compartments. Thus, our findings indicate that H. pylori inhibits the development of a strong Th1-polarizing response in BMDMs stimulated with L. acidophilus by blocking the production of IFN-? in a VacA-dependent manner. We suggest that this abrogation is caused by a redirection of the endocytotic pathway in the processing of L. acidophilus.

Weiss, Gudrun; Forster, Sam; Irving, Aaron; Tate, Michelle; Ferrero, Richard L.; Hertzog, Paul; Fr?kiaer, Hanne; Kaparakis-Liaskos, Maria

2013-01-01

40

Analysis of Expression of CagA and VacA Virulence Factors in 43 Strains ofHelicobacter pyloriReveals that Clinical Isolates Can Be Divided into Two Major Types and that CagA Is Not Necessary for Expression of the Vacuolating Cytotoxin  

Microsoft Academic Search

Colonization of the mucosa of the stomach and the duodenum by Helicobacter pylori is the major cause of acute and chronic gastroduodenal pathologies in humans. Duodenal ulcer formation strongly correlates with the expression of an antigen (CagA) that is usually coexpressed with the vacuolating cytotoxin (VacA), a protein that causes ulceration in the stomach of mice. However, the relationship between

ZHAOYING XIANG; STEFANO CENSINI; PIETRO F. BAYELI; JOHN L. TELFORD; NATALE FIGURA; RINO RAPPUOLI; ANDANTONELLO COVACCI

41

Funcionalidade de sistemas colinergicos em ratos previamente tratados com triiodotironina. (Function of Colinergic systems in rats pre-treated with triiodothyronine).  

National Technical Information Service (NTIS)

In order to investigate the influence of experimental hyperthyroidism on cholinergic activity, rats were injected daily, during 1, 5, 19 or 20 days, with triiodothyronine (0 to 100 ug/kg, s.c.). The hiperthyroidism was evaluated by the decrease of the bod...

O. M. S. Almeida

1990-01-01

42

Helicobacter pylori VacA Toxin Promotes Bacterial Intracellular Survival in Gastric Epithelial Cells  

Microsoft Academic Search

Helicobacter pylori colonizes the gastric epithelium of at least 50% of the world's human population, playing a causative role in the development of chronic gastritis, peptic ulcers, and gastric adenocarcinoma. Current evidence indicates that H. pylori can invade epithelial cells in the gastric mucosa. However, relatively little is known about the biology of H. pylori invasion and survival in host

M. R. Terebiznik; C. L. Vazquez; K. Torbicki; D. Banks; T. Wang; W. Hong; S. R. Blanke; M. I. Colombo; N. L. Jones

2006-01-01

43

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...

44

Síntese de proteína microbiana e concentrações de uréia em vacas alimentadas com dietas à base de palma forrageira e diferentes volumosos  

Microsoft Academic Search

Five Holstein cows were allotted to a 5 × 5 Latin square design with the objective of evaluating the microbial protein production, using the total excretion of purine derivatives (PD), obtained from spot urine collection, plasma and milk urea and nitrogen (N)-urea. The five treatments contained different forage sources: sugar cane bagasse (CB), tifton hay (TH), elephant grass hay (EH),

Marcelo de Andrade Ferreira; Renata Rodrigues da Silva; Alenice Ozino Ramos; Antonia Sherlânea Chaves Véras; Airon Aparecido Silva de Melo; Amanda Vasconcelos Guimarães

2009-01-01

45

Castración de vacas: Una alternativa para mejorar los sistemas de engorde Cows castration: An alternative to improve body weight gain systems  

Microsoft Academic Search

The aim of this work was to analyze the changes in the increase of body weight, meat-bone-fat relation, carcass weight, fat infi l- tration in the muscular mass and blood levels of triiodothyroxine induced by ovariectomy. Two different experiments were done in different fi elds of Argentina, A) young cows, B) old cows. Each experimental group was randomly divided into

Guillermo Edgardo Ashworth; Luis Alberto Poloni; Héctor Fernando Gauna

2007-01-01

46

PRODUÇÃO E COMPOSIÇÃO DO LEITE DE VACAS DA RAÇA HOLANDESA ALIMENTADAS COM FENOS DE ALFAFA E DE TIFTON-85 E SILAGEM DE MILHO  

Microsoft Academic Search

This experiment studied the effects of alfalfa and Tifton-85 hays and of corn silage intake on the production and composition of the milk of multiparous Holstein cows, averaging 460 kg in body weight, in the beginning of their lactation period, in an experiment in triple Latin square, simultaneous, with three lines (for cows) and three columns (for roughage). The cows

CLÓVES CABREIRA JOBIM; GILBERTO ALVES FERREIRA; GEANE DIAS; ULYSSES CECATO; NEWTON POHL RIBAS

47

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...

48

Incremento en la proteína no degradable en rumen de vacas lecheras: 1. Efectos sobre la producción y composición de leche y utilización de nutrientes  

Microsoft Academic Search

SUMMARY One of the most limiting and expensive nutrients for high producing dairy cows is crude protein (CP) and particularly RUP. Winter diets for dairy cattle in Southern Chile are based mainly on silages. The aim of the study was to analize the effects of the level of RUP in diets which include high levels of pasture silage and alfalfa

D Ibarra; L Latrille

2006-01-01

49

Determinación de la excreción total de alantoína en suero de leche por Cromatografía Líquida de Alta Eficiencia (HPLC) en vacas Holstein alimentadas con pasto Kikuyo (Pennisetum clandestinum )  

Microsoft Academic Search

A B S T R A C T Title: Determination of allantoin excre- tion by High Performance Liquid Chromatography (HPLC) in milk serum from Holstein cows fed kikuyu grass (Pennisetum clandestinum). An experiment was carried out to deter- mine allantoin excretion in late lactation dairy cows, using tree multiparous (four lactations or more) Holstein cows, fed exclusively on kikuyu grass

Luis C. Arreaza; Hugo R. Jiménez; Dora E. Sánchez; Leonardo Sánchez

50

Clustering and Redistribution of Late Endocytic Compartments in Response to Helicobacter pylori Vacuolating Toxin  

Microsoft Academic Search

Helicobacter pylori VacA is a secreted protein toxin that may contribute to the pathogenesis of peptic ulcer disease and gastric adenocarcinoma. When added to cultured mammalian cells in the presence of weak bases (e.g., ammonium chloride), VacA induces the formation of large cytoplasmic vacuoles. Here, we report a previously unrecognized capacity of VacA to induce clustering and perinuclear redistribution of

Yi Li; Angela Wandinger-Ness; James R. Goldenring

2004-01-01

51

Application of Bead-ELISA method to detect Helicobacter pyloriVacA  

Microsoft Academic Search

Helicobacter pyloriis an etiological agent of gastritis, gastric ulcer and gastric cancer. In order to clarify the significance of vacuolating cytotoxin (VacA) for the pathogenesis ofHelicobacter pyloriinfection, we established and applied the sandwich bead enzyme-linked immunosorbent assay (Bead-ELISA) for quantitative determination of VacA in the culture mediums ofH. pyloriand other species ofHelicobacter.The minimum concentration of VacA in culture medium detected

Hiroshi Nagata; Akihiro Wada; Hisao Kurazono; Kinnosuke Yahiro; Daisuke Shirasaka; Takahiro Ikemura; Nobuo Aoyama; Wang Ai-ping; Kazuya Makiyama; Shigeru Kohno; Toshiya Hirayama

1999-01-01

52

The Helicobacter pylori Vacuolating Toxin Inhibits T Cell Activation by Two Independent Mechanisms  

Microsoft Academic Search

Helicobacter pylori toxin, VacA, damages the gastric epithelium by erosion and loosening of tight junctions. Here we report that VacA also interferes with T cell activation by two different mech- anisms. Formation of anion-specific channels by VacA prevents calcium influx from the extracellular milieu. The transcription factor NF-AT thus fails to translocate to the nucleus and activate key cytokine genes.

Marianna Boncristiano; Silvia Rossi Paccani; Silvia Barone; Cristina Ulivieri; Laura Patrussi; Dag Ilver; Amedeo Amedei; Mario Milco D'Elios; John L. Telford; Cosima T. Baldari

53

Evolução clínica e laboratorial de crianças com alergia a leite de vaca e ingestão de bebida à base de soja Clinical and laboratorial follow-up of children with cow's milk allergy (CMA) using a soy based beverage  

Microsoft Academic Search

Objective: To evaluate the use of a soy beverage in infants with cow's milk allergy (CMA), considering all nutritional aspects and the development of soy allergy. Methods: Twelve CMA patients with 1 to 4 years old received soy beverage and were subjected to clinical, labo- ratory and nutritional assessment during 12 months. Soy formula samples were evaluated by ELISA technique

Ana Paula; B. M. Castro; Cristina Miuki; A. Jacob; Gabriela Ackel Corradi; Dulcineia Abdalla; Renata F. F. Gonçalves; Fabia Thais; L. Rocha; Antonio Carlos Pastorino

54

LA SUSTITUCION DE MAIZ POR PULP A DE CITRICOS DESHffiRATADA SOBRE LA PRODUCCION Y COMPOSICION LACTEA DE VACAS ENCASTADAS HOLSTEIN EN EL TROPICO HUMEDO DE COSTA RICAl  

Microsoft Academic Search

Se evalu6 la sustituci6n de mafz por pul- Replacement of corn by dehydrated ci- pa de cftricos deshidratada en la dieta de ganado trus pulp on milk production and composition lechero, mediante la inclusi6n de 0, 15,30 Y 45% of crossbred Holstein in the humid tropics. A de la pulpa en el alimento balanceado. EI alimen- study was conducted to

Augusto Rojas-Bourrillon; Luis Gamboa; Milton Villareal

2001-01-01

55

Observations on the Use of Manual Signs and Gestures in the Communicative Interactions between Native Americans and Spanish Explorers of North America: The Accounts of Bernal Diaz del Castillo and Alvar Nunez Cabeza de Vaca  

ERIC Educational Resources Information Center

The accounts of two men who participated in several Spanish-led expeditions to the New World in the early 1500s document the frequent use of manual signs and gestures in the initial interactions between European explorers and the indigenous peoples of North America. Bernal Diaz del Castillo described the events that occurred during three…

Bonvillian, John D.; Ingram, Vicky L.; McCleary, Brendan M.

2009-01-01

56

Observations on the Use of Manual Signs and Gestures in the Communicative Interactions between Native Americans and Spanish Explorers of North America: The Accounts of Bernal Diaz del Castillo and Alvar Nunez Cabeza de Vaca  

ERIC Educational Resources Information Center

|The accounts of two men who participated in several Spanish-led expeditions to the New World in the early 1500s document the frequent use of manual signs and gestures in the initial interactions between European explorers and the indigenous peoples of North America. Bernal Diaz del Castillo described the events that occurred during three…

Bonvillian, John D.; Ingram, Vicky L.; McCleary, Brendan M.

2009-01-01

57

Vacuolating Cytotoxin and Variants in Atg16L1 that Disrupt Autophagy Promote Helicobacter pylori Infection in Humans  

PubMed Central

Background & Aims The Helicobacter pylori toxin vacuolating cytotoxin (VacA) promotes gastric colonization and its presence (VacA+) is associated with more-severe disease. The exact mechanisms by which VacA contributes to infection are unclear. We previously found that limited exposure to VacA induces autophagy of gastric cells, which eliminates the toxin; we investigated whether autophagy serves as a defense mechanism against H pylori infection. Methods We investigated the effect of VacA on autophagy in human gastric epithelial cells (AGS) and primary gastric cells from mice. Expression of p62, a marker of autophagy, was also assessed in gastric tissues from patients infected with toxigenic (VacA+) or nontoxigenic strains. We analyzed the effect of VacA on autophagy in peripheral blood monocytes obtained from subjects with different genotypes of ATG16L1, which regulates autophagy. We performed genotyping for ATG16L1 in two cohorts of infected and uninfected subjects. Results Prolonged exposure of AGS and mouse gastric cells to VacA disrupted induction of autophagy in response to the toxin, because the cells lacked cathepsin-D in autophagosomes. Loss of autophagy resulted in the accumulation of p62 and reactive oxygen species. Gastric biopsies samples from patients infected with VacA+, but not nontoxigenic strains of H pylori, had increased levels of p62. Peripheral blood monocytes isolated from individuals with polymorphisms in ATG16L1 that increase susceptibility to Crohn's disease had reduced induction of autophagy in response to VacA+ compared to cells from individuals that did not have these polymorphisms. The presence of the ATG16L1 Crohn’s disease risk variant increased susceptibility to H pylori infection in 2 separate cohorts. Conclusions Autophagy protects against infection with H pylori; the toxin VacA disrupts autophagy to promote infection, which could contribute to inflammation and eventual carcinogenesis.

Raju, D; Hussey, S; Ang, M; Terebiznik, M.R.; Sibony, M; Galindo-Mata, E; Gupta, V; Blanke, S.R.; Delgado, A; Romero-Gallo, J; Ramjeet, M; Mascarenhas, H; Peek, R.M.; Correa, P; Streutker, C; Hold, G; Kunstmann, E; Yoshimori, T; Silverberg, M. S.; Girardin, S.E.; Philpott, D.J.; El Omar, E; Jones, N.L.

2012-01-01

58

Uptake of Helicobacter pylori outer membrane vesicles by gastric epithelial cells.  

PubMed

Helicobacter pylori bacteria colonize the human stomach where they stimulate a persistent inflammatory response. H. pylori is considered noninvasive; however, lipopolysaccharide (LPS)-enriched outer membrane vesicles (OMV), continuously shed from the surface of this bacterium, are observed within gastric epithelial cells. The mechanism of vesicle uptake is poorly understood, and this study was undertaken to examine the roles of bacterial VacA cytotoxin and LPS in OMV binding and cholesterol and clathrin-mediated endocytosis in vesicle uptake by gastric epithelial cells. OMV association was examined using a fluorescent membrane dye to label OMV, and a comparison was made between the associations of vesicles from a VacA(+) strain and OMV from a VacA(-) isogenic mutant strain. Within 20 min, essentially all associated OMV were intracellular, and vesicle binding appeared to be facilitated by the presence of VacA cytotoxin. Uptake of vesicles from the VacA(+) strain was inhibited by H. pylori LPS (58% inhibition with 50 ?g/ml LPS), while uptake of OMV from the VacA(-) mutant strain was less affected (25% inhibition with 50 ?g/ml LPS). Vesicle uptake did not require cholesterol. However, uptake of OMV from the VacA(-) mutant strain was inhibited by a reduction in clathrin-mediated endocytosis (42% with 15 ?g/ml chlorpromazine), while uptake of OMV from the VacA(+) strain was less affected (25% inhibition with 15 ?g/ml chlorpromazine). We conclude that VacA toxin enhances the association of H. pylori OMV with cells and that the presence of the toxin may allow vesicles to exploit more than one pathway of internalization. PMID:20876296

Parker, Heather; Chitcholtan, Kenny; Hampton, Mark B; Keenan, Jacqueline I

2010-09-27

59

Helicobacter pylori-Associated Gastritis in Mice is Host and Strain Specific  

Microsoft Academic Search

The vacA and cagA geno- and phenotypes of two mouse-adapted strains of Helicobacter pylori, SS1 and SPM326, were determined. The SS1 strain, which had the cagA1 and vacA s2-m2 genotype, induced neither vacuole formation in HeLa cells nor interleukin-8 (IL-8) production in KATO III cells. In contrast, H. pylori SPM326, with the cagA1 and vacA s1b-m1 genotype, induced vacuoles as

NATHALIE E. M. VAN DOORN; FERRY NAMAVAR; MARION SPARRIUS

1999-01-01

60

Atomic Layer Deposition- and Chemical Vapor Deposition-TiN Top Electrode Optimization for the Reliability of Ta2O5 and Al2O3 Metal Insulator Silicon Capacitor for 0.13 ?m Technology and Beyond  

NASA Astrophysics Data System (ADS)

TiCl4-based atomic layer deposition (ALD)- and chemical vapor deposition (CVD)-TiN films are applied as the metal top electrode for Ta2O5 and Al2O3 metal insulator silicon (MIS) capacitor. The effects of factors such as Cl content, step coverage, deposition temperature of the TiN top electrode processes and pre-NH3 flushing on the electrical properties and reliability of the Ta2O5 and Al2O3 MIS capacitor are studied. Among these factors, poor step coverage shows distinctly degraded electrical properties of MIS capacitor, and high deposition temperature of TiN processes also degraded electrical properties, particularly those of Ta2O5. Although similar capacitance and leakage characteristics are measured with high chlorine content and pre-NH3 flushing TiN processes, a difference in the orders of magnitude is observed in time dependent dielectric breakdown (TDDB) measurements. Regarding the deposition temperature and pre-NH3 flushing effect, the electrical and TDDB characteristics of Ta2O5 degrade even more severely than those of Al2O3. Degradation of TDDB in TiN films with NH3 flushing prior to deposition is attributed to the reduction effect of the dielectric material by NH3 gas. Based on the X-ray photoelectron spectroscopy (XPS) analysis results, Al2O3 is chemically more inert than Ta2O5. In addition, the degradation of TDDB characteristics is directly correlated to the early generation of Vp-dependent solid “0” fail bit counts. Due to the relatively low deposition temperature as well as to the excellent step coverage and low resistivity, the ALD-TiN process is ideal for enhancing the reliability of a MIS capacitor.

Lim, Hyun Seok; Kang, Sang Bom; Jeon, In Sang; Choi, Gil Heyun; Park, Young Wook; Lee, Sang In; Moon, Joo Tae

2001-04-01

61

Void Lattice Formation: Spinodal Decomposition of Vacancies.  

National Technical Information Service (NTIS)

Superlattices of voids form in various metallic crystals and alloys under conditions of heavy radiation damage near the threshold temperature of void formation. The mechanism of the void lattice formation is considered as a spinodal decomposition, of vaca...

M. Imada

1978-01-01

62

Expression of Helicobacter pylori Vacuolating Toxin in Escherichia coli  

PubMed Central

VacA is a secreted toxin that plays a role in Helicobacter pylori colonization of the stomach and that contributes to the pathogenesis of peptic ulcer disease. Studies of VacA structure and function have been hindered by the lack of an efficient system for expression and genetic manipulation of this toxin. In this study, we developed methodology for expression of a functionally active VacA toxin in Escherichia coli. We then used a high-throughput screen to analyze a library of mutant toxins with pentapeptide insertions and identified six mutants that lacked the capacity to induce vacuolation of HeLa cells. The capacity to analyze VacA in this heterologous-expression system should greatly facilitate efforts to elucidate the structure and function of this toxin.

McClain, Mark S.; Cover, Timothy L.

2003-01-01

63

Helicobacter pylori Vacuolating Cytotoxin Inhibits T Lymphocyte Activation  

Microsoft Academic Search

Helicobacter pylori (Hp) vacuolating cytotoxin VacA induces cellular vacuolation in epithelial cells. We found that VacA could efficiently block proliferation of T cells by inducing a G1\\/S cell cycle arrest. It interfered with the T cell receptor\\/interleukin-2 (IL-2) signaling pathway at the level of the Ca2+-calmodulin-dependent phosphatase calcineurin. Nuclear translocation of nuclear factor of activated T cells (NFAT), a transcription

Bettina Gebert; Wolfgang Fischer; Evelyn Weiss; Reinhard Hoffmann; Rainer Haas

2003-01-01

64

Helicobacter pylori induced interleukin-8 expression in gastric epithelial cells is associated with CagA positive phenotype  

Microsoft Academic Search

AIMS--To use a range of natural phenotypically variant strains of Helicobacter pylori with disparate CagA and VacA (vacuolating cytotoxin) expression to determine which bacterial factors are more closely associated with epithelial interleukin-8 (IL-8) induction. METHODS--Gastric epithelial cells (AGS and KATO-3) were co-cultured with five H pylori strains which were variously shown to express the cagA gene\\/CagA protein, VacA and\\/or to

J E Crabtree; A Covacci; S M Farmery; Z Xiang; D S Tompkins; S Perry; I J Lindley; R Rappuoli

1995-01-01

65

Multiple Oligomeric States of the Helicobacter pylori Vacuolating Toxin Demonstrated by Cryo-electron Microscopy  

Microsoft Academic Search

Helicobacter pylori vacuolating toxin (VacA) is a bacterial protein toxin that forms water-soluble oligomeric complexes, and can somehow insert into lipid bilayers to produce anion-selective channels. In this study, we utilize the novel technique of “cryo-negative staining” to examine the morphology of vitrified VacA complexes. Two basic types of oligomeric structures were observed: (i) relatively thick six or seven-sided astral

Marc Adrian; Jacques Dubochet; John E. Heuser

2002-01-01

66

Inhibition of vacuolation toxin activity of Helicobacter pylori by iodine, nitrite and potentiation by sodium chloride, sterigmatocystin and fluoride  

Microsoft Academic Search

The toxin VacA produced by Helicobacter pylori is an important determinant of virulence. VacA causes vacuolation of cultured cells such as HeLa cells. Iodine, nitrite, sodium chloride, thiocyanate and fungus toxin sterigmatocystin are universally present in nature and could possibly be related to carcinogenesis of the stomach. The present study was designed to examine the effects of the above-mentioned compound

Fengjuan Ma; Wenyuan Zhao; Masanobu Kudo; Kazuo Aoki; Junichi Misumi

2002-01-01

67

Correlação entre os métodos infravermelho e ultra-som na determinação da composição química do leite das vacas do concurso leiteiro da Expointer 2007 Correlation between infra-red and ultra-sound methods to evaluate milk composition in milk contest at EXPOINTER 2007  

Microsoft Academic Search

Expointer is one of the most important events of cattle breeding in Latin America, where the main species and production animals are showed. The objective of this research was to evaluate the chemical composition and somatic cells count in dairy cow's milk that were evaluated at milk production contest at Expointer 2007. It intents to correlate two analyti c methods

Andrea Troller Pinto; Maira Balbinotti Zanela; Maria Edi Rocha Ribeiro; Victoria Noel Vázquez; Jabson de Oliveira Santos

68

EFEITO DE DIFERENTES COMBINAÇÕES HORMONAIS SOBRE A TAXA DE RETORNO AO ESTRO E PRENHEZ EM VACAS DE CORTE LACTANDO, SUBMETIDAS À INSEMINAÇÃO ARTIFICIAL EM TEMPO FIXO. EFFECT OF DIFFERENT HORMONAL COMBINATIONS ON RETURN TO ESTRUS AND PREGNANCY RATES IN LACTATING BEEF COWS, SUBJECTED TO A FIXED TIME INSEMINATION  

Microsoft Academic Search

The objective of this study was to evaluate the effect of the Gonadotropin Releasing Hormone (GnRH) and of the Equine Chorionic Gonadotropin (eCG) and their association on conception and pregnancy rates in lactating beef cows, subjected to fixed-time artificial insemination (FTAI). In this study, 223 crossbred cows, with 65.9% presenting body condition scores < 3, were used.The treatment 1 (TC

Eduardo Schmitt; Elias Moura Luz; Ivan Bianchi; Eduardo Bunselmeyer; Ferreira Filho; Marcio Nunes Corrêa; Thomaz Lucia; João Carlos Deschamps

2007-01-01

69

Valores hematológicos en vacas de raza Holstein-Friesian seropositivas a Neospora caninum de la cuenca lechera de Tizayuca, Hidalgo, México* Hematological values in Holstein-Frie sian Neospora caninum seropositive cows from the dairy cattle region of Tizayuca in the State of Hidalgo in Mexico  

Microsoft Academic Search

Since bovine neosporosis has only recently been recognized in Mexico, not sufficient clinical or pathological analyses have been carried out upon this parasite. The aim of this study was to find out if there were variations in hematological values of cows found to be positive to anti-Neospora caninum antibodies which could carry latent tachyzoites in tissues, as compared with cows

Pablo Calzada Calzada; Elizabeth Morales Salinas; Gerardo F. Quiroz-Rocha; Frida Salmerón Sosa; Carlos García Ortiz; Javier Hernández Balderas

70

In silico investigation and structural characterization of virulent factor and a metallo peptidase present in Helicobacter pylori strain J99.  

PubMed

VacA is a high-molecular weight multimeric pore-forming protein encoded by the chromosomal gene vacA of Helicobacter pylori J99 strian. It plays a significant role in the development of gastric cancer in human by inducing the formation of vacuoles. Genomics and proteomics features of an organism have provided a plethora of potential drug targets. The crystal structure of VacA is not available in any structural database; hence a 3D structure is very essential for structural studies and discovery of potential inhibitors against proteins. In this study 3D structure of VacA is modelled a by using Bhageerath: an energy based web enabled computer software suite. According to our study VacA steriochemical validation shows 91.7% residues are in allowed region of Ramachandran plot. Further validation was done by WHAT CHECK to provide evidence that the distribution of the main chain bond lengths and omega bond angles were within limits with Z-score 1.0 and error values are negligible. The modelled protein was submitted to Protein Model Database and can be downloaded with PMDID PM0077963. Further we found that metallo peptidase "M3" cleaves VacA and helps in import mechanism in mitochondria. Structure of metallo peptidase is also not available in any structural database so we modelled and validated its structure. With the help of docking studies we blocked the active site of metallo peptidase by ligand LA3 and 294 with binding energy -5.9 and -5.2 KJ/mol respectively, thus prevented import mechanism of VacA in mitochondria. The inhibitors identified from our study were LA3 and 294 ligands. The investigation concluded that these drugs could be used as the potential inhibitors against the damage of stomach and duodenum, which ultimately reduces the likelihood of ulcer as well as gastric cancer. PMID:23354820

Vaidya, Megha; Panchal, Hetalkumar

2013-01-26

71

DNA-Level Characterization of Helicobacter pylori Strains from Patients with Overt Disease and with Benign Infections in Bangladesh  

PubMed Central

The complex relation between the genotype of Helicobacter pylori and its association with clinical outcome is not well understood. Studies in the West have showed that strains expressing certain virulence factors (vacAs1, vacAm1, and cagA) are associated with duodenal ulcer disease. However, the H. pylori genotype is known to vary with geographic region. In the present study, we compared several virulence markers (cagA, vacA, and iceA) and neutral markers (IS605, IS606, and IS608) in H. pylori strains isolated from 65 adult patients with peptic ulcer (PU) and 50 patients with nonulcer dyspepsia (NUD). PCR tests indicated that cagA is present in 75% of the strains from patients with PU compared to 55% in patients with NUD, and 80% of the isolates from patients with PU carried potentially toxigenic vacAs1 alleles of the vacuolating cytotoxin gene (vacA) compared to 60% in isolates from patients with NUD. However, no significant difference in any other virulence marker was observed in isolates from both groups. Phylogenetic analysis of the vacA middle region and the 5? end of the cagA gene indicates that Bangladeshi isolates are more closely related to H. pylori isolates from India and are different from isolates from East Asia.

Rahman, Motiur; Mukhopadhyay, Asish K.; Nahar, Shamsun; Datta, Simanti; Mashhud Ahmad, Milan; Sarker, Safique; Masud, Ibna M.; Engstrand, Lars; Albert, M. John; Nair, G. Balakrish; Berg, Douglas E.

2003-01-01

72

The Characterization of Helicobacter pylori DNA Associated with Ancient Human Remains Recovered from a Canadian Glacier  

PubMed Central

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of nearly half of the world's population. Genotypic characterization of H. pylori strains involves the analysis of virulence-associated genes, such as vacA, which has multiple alleles. Previous phylogenetic analyses have revealed a connection between modern H. pylori strains and the movement of ancient human populations. In this study, H. pylori DNA was amplified from the stomach tissue of the Kwäday Dän Ts'ìnchi individual. This ancient individual was recovered from the Samuel Glacier in Tatshenshini-Alsek Park, British Columbia, Canada on the traditional territory of the Champagne and Aishihik First Nations and radiocarbon dated to a timeframe of approximately AD 1670 to 1850. This is the first ancient H. pylori strain to be characterized with vacA sequence data. The Tatshenshini H. pylori strain has a potential hybrid vacA m2a/m1d middle (m) region allele and a vacA s2 signal (s) region allele. A vacA s2 allele is more commonly identified with Western strains, and this suggests that European strains were present in northwestern Canada during the ancient individual's time. Phylogenetic analysis indicated that the vacA m1d region of the ancient strain clusters with previously published novel Native American strains that are closely related to Asian strains. This indicates a past connection between the Kwäday Dän Ts'ìnchi individual and the ancestors who arrived in the New World thousands of years ago.

Swanston, Treena; Haakensen, Monique; Deneer, Harry; Walker, Ernest G.

2011-01-01

73

Helicobacter pylori Virulence Genes Detected by String PCR in Children from an Urban Community in Northeastern Brazil  

PubMed Central

The accuracy of a nested PCR in gastric DNA obtained by a string test for the diagnosis of Helicobacter pylori infection in asymptomatic children was 94.0%. The cagA-positive toxigenic vacAs1m1 strains were the most prevalent strains, indicating that this population is colonized early by the strains associated with gastric cancer.

Goncalves, Maria H. R. B.; Silva, Cicero I. S. M.; Braga-Neto, Manuel B.; Fialho, Andrea B. C.; Fialho, Andre M. N.; Queiroz, Dulciene M. M.

2013-01-01

74

Impact of Helicobacter pylori Virulence on the Outcome of Gastroduodenal Diseases: Lessons from the Microbiologist  

Microsoft Academic Search

Two main pathogenic factors have been described in Helicobacter pylori strains: the cag pathogenicity island (cag PAI) and the vacuolating cytotoxin VacA. The cag PAI is comprised of approximately 40 open reading frames probably originating from another species. It encodes a type IV secretion system, i.e., an apparatus derived from pili which may contribute to the transfer of bacterial molecules

Francis Mégraud

2001-01-01

75

Cell culture assays to evaluate bacterial toxicity and virulence.  

PubMed

Helicobacter pylori CagA and VacA are two critical virulence factors that modulate disease severity in the infected host. The following chapter outlines methods employed to study the effects of these virulence factors on several key signaling pathways in epithelial cells. PMID:23015494

Raju, Deepa; Rizzuti, David; Jones, Nicola L

2012-01-01

76

Conservation of Helicobacter pylori genotypes in different ethnic groups in Houston, Texas.  

PubMed

This study was concerned with whether the Helicobacter pylori strains circulating among ethnic groups living in the same region differ. The polymerase chain reactions to genotype (cagA, vacA, and iceA) H. pylori isolates from healthy volunteers from 4 ethnic groups (black, n=35; white Hispanic, n=31; whites, n=30; Vietnamese, n=29) residing in Houston were examined. The Vietnamese volunteers had the "East Asian"-type cagA 3' repeat region structure, and the others had the "non-Asian" type. The most common genotypes were delineated as follows: blacks and Hispanics, cagA+, vacA s1b-m1, and iceA2; whites, cagA+, vacA s1a-m2, and iceA2; and Vietnamese, cagA+, vacA s1c-m2, and iceA2. Two Hispanic families were also examined. H. pylori isolates from the children and their mothers had the same genotype and were different from those associated with the children's fathers or brothers-in-law. Conservation of an H. pylori genotype within ethnic groups over the course of generations will prove useful for epidemiological study of the coevolution of humans and H. pylori. PMID:10837199

Yamaoka, Y; Malaty, H M; Osato, M S; Graham, D Y

2000-06-05

77

Helicobacter pylori in dental plaque and stomach of patients from Northern Brazil  

PubMed Central

AIM: To establish whether virulence factor genes vacA and cagA are present in Helicobacter pylori (H. pylori) retrieved from gastric mucosa and dental plaque in patients with dyspepsia. METHODS: Cumulative dental plaque specimens and gastric biopsies were submitted to histological examination, rapid urease test and polymerase chain reaction (PCR) assays to detect the presence of cagA and vacA polymorphisms. RESULTS: Detection of H. pylori from dental plaque and gastric biopsy samples was greater by PCR compared to histological examination and the rapid urease test. DNA from H. pylori was detected in 96% of gastric mucosa samples and in 72% of dental plaque samples. Sixty-three (89%) of 71 dental plaque samples that were H. pylori-positive also exhibited identical vacA and cagA genotypes in gastric mucosa. The most common genotype was vacAs1bm1 and cagA positive, either in dental plaque or gastric mucosa. These virulent H. pylori isolates were involved in the severity of clinical outcome. CONCLUSION: These pathogenic strains were found simultaneously in dental plaque and gastric mucosa, which suggests that gastric infection is correlated with the presence of H. pylori in the mouth.

Assumpcao, Monica Barauna; Martins, Luisa Caricio; Melo Barbosa, Hivana Patricia; dos Santos Barile, Katarine Antonia; de Almeida, Sintia Silva; Assumpcao, Paulo Pimentel; de Oliveira Corvelo, Tereza Cristina

2010-01-01

78

Stalagmite evidence from Belize indicating significant droughts at the time of Preclassic Abandonment, the Maya Hiatus, and the Classic Maya collapse  

Microsoft Academic Search

Paleoenvironmental data from a stalagmite from western Belize provide a 3300-year record of droughts that impacted the Maya civilization at least four times across a span of 1500 years, and the most sustained period of drought coincided with the collapse of Classic Maya civilization. The stalagmite, which comes from Macal Chasm in the Vaca Plateau, provides reliably dated reflectance, color, luminescence,

James W. Webster; George A. Brook; L. Bruce Railsback; Hai Cheng; R. Lawrence Edwards; Clark Alexander; Philip P. Reeder

2007-01-01

79

El sexo recompensado: una práctica en el centro de las vulnerabilidades (ITS\\/VIH\\/SIDA) de las jóvenes mexicanas  

Microsoft Academic Search

Objective. To discuss the risks for Mexican young women who engage in sexual relations in exchange for social or economic benefits, also known as compensated sex (CS), with the objective of exploring its possible public health implications. Material and Methods. This is a qualitative study conducted in youths 15 to 25 years of age in Cuerna- vaca, Morelos, Mexico, between

Florence Lise Théodore; Juan Pablo Gutiérrez; Pilar Torres; Gabriela Luna

2004-01-01

80

Bauhcis moranii gen. et sp. nov. (Cercideae, Caesalpinieae), an Oligocene plant from Tepexi de Rodr??guez, Puebla, Mex., with leaf architecture similar to Bauhinia and Cercis  

Microsoft Academic Search

The Oligocene Coatzingo Formation (?Pie de Vaca Formation), Puebla, Mexico, has yielded a diverse assemblage of plants among which Leguminosae are represented by wood, fruits and leaves or leaflets. Leaf impressions from two specimens have characteristics found in extant members of Cercideae (Caesalpinieae). Morphological observations were corroborated through a phenetic analysis suggesting that morphological differences between the fossil and extant

Laura Calvillo-Canadell; Sergio R. S Cevallos-Ferriz

2002-01-01

81

Historic Indian Groups of the Choke Canyon Reservoir and Surrounding Area, Southern Texas: Volume I.  

National Technical Information Service (NTIS)

The study analyzes most of the cultural information recorded for each named Indian group that is relatable to the Choke Canyon Reservoir area of southern Texas. This has involved all the Indian groups named by Cabeza de Vaca for the area west and southwes...

T. N. Campbell T. J. Campbell

1981-01-01

82

Prevalence of Helicobacter pylori virulence genotypes among children in Eastern Turkey  

PubMed Central

AIM: To identify the virulence genotypes of Helicobacter pylori (H. pylori) if present in children in Eastern Turkey and if those genotypes are mostly associated with severe clinical presentations. METHODS: A total of 49 H. pylori positive Turkish children (42 with antral nodularity and 7 with peptic ulcer) who underwent upper gastrointestinal endoscopy with abdominal symptoms during the period from March 2011 to September 2012 were enrolled in this study. Antral nodularity was diagnosed endoscopically by two of the authors. We determined for the presence of cagA, vacA, cagE, iceA and babA2 genotypes of H. pylori isolates in DNA obtained directly from frozen gastric biopsy samples by polymerase chain reaction test using specific primers. RESULTS: Of the 49 H. pylori isolates studied, 61.2%, 91.8%, 22.4%, 28.6%, 57.1% and 40.8% were positive for the cagA, vacA s1, cagE, iceA1, iceA2 and babA2 genes, respectively. We showed that the most common vacA subtype was s1a (79.6%). However, the s2 gene was found less frequently with an isolation rate of 8.2% of the H. pylori isolates. The genotypes iceA2 and vacA s1m2 were the most frequently found types in children with antral nodularity. In addition, the genotypes iceA1, babA2 and vacA s1m1 were found in similar ratios in all the H. pylori isolates obtained from children with peptic ulcer. The genotypes vacA s2m1 and s1c were not observed in any of isolates studied. CONCLUSION: This study showed that vacA s1m2, cagA and iceA2 were the most common genotypes, and no association between antral nodularity and genotypes was observed.

Ozbey, Gokben; Dogan, Yasar; Demiroren, Kaan

2013-01-01

83

Association of iceA and babA genotypes in Helicobacter pylori strains with patient and strain characteristics.  

PubMed

Data on the geographic prevalence of Helicobacter pylori iceA and babA alleles in Eastern Europe are still relatively scant. The aim of this study was to evaluate the prevalence of iceA and babA genotypes in Bulgarian symptomatic patients. The iceA and babA genotypes were evaluated by PCR with pure cultures in strains from 196 and 181 patients, respectively. Mixed infections were found in 10.2% of all 196 patients. Prevalence of H. pylori genotypes in patients with single-strain infections was 69.3% for iceA1, 30.7% for iceA2, 82.4% for cagA(+), 89.2% for vacA s1, 10.8% for vacA s2, 39.8% for vacA m1, 60.2% for vacA m2 and 48.8% for babA2. Within the iceA1 positive strains, 94.3% and 88.5% were also vacA s1a and cagA positive, respectively. Of the babA2 positive strains, 100.0%, 92.4% and 72.2% were also vacA s1a, cagA and iceA1 positive, respectively. Ulcer patients had more often strains with cagA positive status and vacA s1a allele. Although neither iceA1 nor babA2 were more common in ulcer patients, the combination of both alleles was more frequent (48.1%) in the ulcer patients than in the rest (28.7%). Clarithromycin susceptible strains had more often iceA1 allele (74.4%) than the resistant strains (55.3%). In conclusion, the results demonstrated a high prevalence of virulent H. pylori in Bulgaria. Both iceA1 and babA2 genotypes were associated with other virulence factors of H. pylori and, in addition, the iceA1 allele was associated with the strain susceptibility. PMID:20454856

Boyanova, Lyudmila; Yordanov, Daniel; Gergova, Galina; Markovska, Rumyana; Mitov, Ivan

2010-05-08

84

Outer membrane targeting of passenger proteins by the vacuolating cytotoxin autotransporter of Helicobacter pylori.  

PubMed

Helicobacter pylori produces a number of proteins associated with the outer membrane, including adhesins and the vacuolating cytotoxin. These proteins are supposed to integrate into the outer membrane by beta-barrel structures, characteristic of the family of autotransporter proteins. By using the SOMPES (shuttle vector-based outer membrane protein expression) system for outer membrane protein production, we were able to functionally express in H. pylori the cholera toxin B subunit genetically fused to the C-terminal VacA domain. We demonstrate that the fusion protein is translocated to the H. pylori outer membrane and that the CtxB domain is exposed on the H. pylori surface. Thus, we provide the first experimental evidence that the C-terminal beta-domain of VacA can transport a foreign passenger protein to the H. pylori surface and hence acts as a functional autotransporter. PMID:11598049

Fischer, W; Buhrdorf, R; Gerland, E; Haas, R

2001-11-01

85

Kinetics and Mechanisms of Extracellular Protein Release by Helicobacter pylori  

PubMed Central

To investigate the kinetics and mechanisms of extracellular protein release by Helicobacter pylori, we analyzed the entry of metabolically radiolabeled bacterial proteins into broth culture supernatant. At early time points, vacuolating cytotoxin (VacA) constituted a major extracellular protein. Subsequently, culture supernatants accumulated many proteins that were components of intact bacterial cells. This nonselective release of proteins was associated with a decreasing turbidity of cultures and loss of bacterial viability, indicative of an autolytic process. The rates of VacA secretion and autolysis were each influenced by medium composition, and therefore these may be regulated phenomena. Extracellular release of proteins by H. pylori may be an important adaptation that facilitates the persistence of H. pylori in the human gastric mucus layer. Moreover, entry of proinflammatory proteins into the gastric mucosa may contribute to the induction of a mucosal inflammatory response.

Schraw, Wayne; McClain, Mark S.; Cover, Timothy L.

1999-01-01

86

Helicobacter pylori in North and South America before Columbus.  

PubMed

We present a molecular epidemiologic study, based on an analysis of vacA, cagA and cag right end junction genotypes from 1042 Helicobacter pylori isolates, suggesting that H. pylori was present in the New World before Columbus. Eight Native Colombian and Alaskan strains possessed novel vacA and/or cagA gene structures and were more closely related to East Asian than to non-Asian H. pylori. Some Native Alaskan strains appear to have originated in Central Asia and to have arrived after strains found in South America suggesting that H. pylori crossed the Bering Strait from Asia to the New World at different times. PMID:12062433

Yamaoka, Yoshio; Orito, Etsuro; Mizokami, Masashi; Gutierrez, Oscar; Saitou, Naruya; Kodama, Tadashi; Osato, Michael S; Kim, Jong G; Ramirez, Francisco C; Mahachai, Varocha; Graham, David Y

2002-04-24

87

Cholesterol Depletion Reduces Helicobacter pylori CagA Translocation and CagA-Induced Responses in AGS Cells  

Microsoft Academic Search

Infection with Helicobacter pylori cagA-positive strains is associated with gastritis, ulcerations, and gastric cancer. CagA is translocated into infected epithelial cells by a type IV secretion system and can be tyrosine phosphorylated, inducing signal transduction and motogenic responses in epithelial cells. Cellular cholesterol, a vital component of the membrane, contributes to membrane dynamics and functions and is important in VacA

Chih-Ho Lai; Yun-Chieh Chang; Shin-Yi Du; Hung-Jung Wang; Chun-Hsien Kuo; Shih-Hua Fang; Hua-Wen Fu; Hui-Hao Lin; Ann-Shyn Chiang; Wen-Ching Wang

2008-01-01

88

Microevolution between paired antral and paired antrum and corpus Helicobacter pylori isolates recovered from individual patients  

Microsoft Academic Search

Sequencevariationslocatedatthesignalsequenceandmid-regionwithinthevacAgene,the39-end of the cagA gene, the indel motifs at the 39-end of the cag pathogenicity island and the regions upstream of the vacA and ribA genes were determined by PCR in 19 paired antral or antrum and corpusHelicobacterpyloriisolatesobtained atthesameendoscopic session,andthreeantralpairs taken sequentially. Random amplification of polymorphic DNA (RAPD)-PCR and fluorescent amplified fragment length polymorphism (FAFLP)-PCR fingerprinting were applied to these

I. M. Carroll; Niyaz Ahmed; Sarah M. Beesley; Aleem A. Khan; Sheikh Ghousunnissa; Colm A. OMorain; C. M. Habibullah

2004-01-01

89

Cytotoxic Action of Serratia marcescens Hemolysin on Human Epithelial Cells  

Microsoft Academic Search

Incubation of human epithelial cells with nanomolar concentrations of chromatographically purified Serratia marcescens hemolysin (ShlA) caused irreversible vacuolation and subsequent lysis of the cells. Vacuolation differed from vacuole formation by Helicobacter pylori VacA. Sublytic doses of ShlA led to a reversible depletion of intracellular ATP. Restoration to the initial ATP level was presumably due to the repair of the toxin

RALF HERTLE; MARTINA HILGER; SANDRA WEINGARDT-KOCHER

90

Pediatric Helicobacter pylori Isolates Display Distinct Gene Coding Capacities and Virulence Gene Marker Profiles  

Microsoft Academic Search

Helicobacter pylori strains display remarkable genetic diversity, and the presence of strains bearing the toxigenic vacA s1 allele, a complete cag pathogenicity island (PAI), cagA alleles containing multiple EPIYA phosphorylation sites, and expressing the BabA adhesin correlates with development of gastroduodenal disease in adults. To better understand the genetic variability present among pediatric strains and its relationship to disease, we

Sarah Talarico; Benjamin D. Gold; Jutta Fero; Dexter T. Thompson; Jeannette Guarner; Steven Czinn; Nina R. Salama

2009-01-01

91

Analysis of Helicobacter pylori genotypes in Afghani and Iranian isolates.  

PubMed

The geographical variation in Helicobacter pylori genotypes is an observed phenomenon. Cytotoxin associated genes A (cagA) and E (cagE), and vacuolating cytotoxin (vacA) genotypes of H. pylori are associated with peptic ulcer disease (PUD). This study compared the distribution of these genotypes in Iranian and Afghani isolates and their association with clinical outcomes. H. pylori infected patients, as proven by positive culture, were recruited prospectively. A total of 70 patients, 55 Iranian (26 men and 29 women, mean age 48 +/- 18 years) and 15 Afghani immigrants (13 men and 2 women, mean age 34.8 +/- 11 years) living in Tehran, Iran were enrolled in this study. DNA was extracted from isolated H. pylori and polymerase chain reaction was carried out to determine the cagA and cagE status and vacA alleles. The number of gastric cancer, peptic ulcer and gastritis cases was 11, 23 and 36, respectively. The cagA positive isolates were more common in Iranian (67%) than Afghani isolates (60%). cagE was positive in 53% of Afghani compared to 51% of Iranian isolates. The most common vacA s-region genotype was s1; 80% in Afghani and 67% in Iranian. The slml was a frequently observed genotype in Afghani strains (53%) while s1m2 (47%) was more common in strains isolated from Iranian patients. There is a difference in the H. pylori strains between Iranian and Afghani groups, for instance Iranian isolates were similar to European isolates while Afghani isolates were similar to isolates from India. However, there was no significant association between cagA, cagE and vacA genotypes and clinical outcomes in Iranian and Afghani patients. PMID:20568532

Dabiri, Hossein; Bolfion, Mehdi; Mirsalehian, Akbar; Rezadehbashi, Maryam; Jafari, Fereshteh; Shokrzadeh, Leila; Sahebekhtiari, Navid; Zojaji, Homayon; Yamaoka, Yoshio; Mirsattari, Darioush; Zali, Mohammad Reza

2010-01-01

92

DNA-Level Characterization of Helicobacter pylori Strains from Patients with Overt Disease and with Benign Infections in Bangladesh  

Microsoft Academic Search

The complex relation between the genotype of Helicobacter pylori and its association with clinical outcome is not well understood. Studies in the West have showed that strains expressing certain virulence factors (vacAs1, vacAm1, and cagA) are associated with duodenal ulcer disease. However, the H. pylori genotype is known to vary with geographic region. In the present study, we compared several

Motiur Rahman; Asish K. Mukhopadhyay; Shamsun Nahar; Simanti Datta; Milan Mashhud Ahmad; Safique Sarker; Ibna M. Masud; Lars Engstrand; M. John Albert; G. Balakrish Nair; Douglas E. Berg

2008-01-01

93

Association of peptic ulcer with increased expression of Lewis antigens but not cagA, iceA, andvacA in Helicobacter pylori isolates in an Asian population  

Microsoft Academic Search

BACKGROUNDStudies in Western populations suggest that cagA, iceA, and vacAgene status in Helicobacter pylori isolates is associated with increased virulence and peptic ulcer disease.AIMTo investigate the relationship between peptic ulcer and expression of Lewis (Le) antigens as well as cagA, iceA, and vacA inH pylori isolates in Singapore.METHODSExpression of Le antigens in H pylori isolates obtained from patients with dyspepsia

P Y Zheng; J Hua; K G Yeoh; B Ho

2000-01-01

94

Determination of Helicobacter pylori Virulence Genes in Gastric Biopsies by PCR  

PubMed Central

Aim. The aim of this study was to identify the presence of H. pylori in biopsy specimens from symptomatic patients by PCR. In addition, the rate of cagA, vacA, iceA1, and iceA2 virulence genes was determined. Materials and Methods. One hundred antral gastric biopsy specimens were collected during endoscopy from patients suffering from gastroduodenal symptoms. The samples were collected by the gastroenterologists in their own clinics in Ramallah, Palestine. DNA was extracted from the biopsies and subsequently used for PCR identification of H. pylori and the virulence genes using specific primers. Results. The rate of positive H. pylori in the collected biopsies was 44%. The rates of the virulence genes in this sample: cagA, vacA, iceA1, and iceA2 were 65.9%, 40.9%, 63.6%, and 84.1%, respectively. Conclusion. The iceA2 gene was the most frequent in this study. Much research is necessary to determine the presence of an association of this gene with gastric pathology. Variation in the rates of the iceA gene in different countries is a strong indication of its geographical distribution. This study would provide important information regarding the prevalence of virulence genes (vacA, cagA, iceA1, and iceA2) in H. pylori strains in the sample tested in this country.

Hammoudeh, Wail; Sabri, Israr; Sweidan, Walid; Farraj, Mohammad A.

2013-01-01

95

Determination of Helicobacter pylori Virulence Genes in Gastric Biopsies by PCR.  

PubMed

Aim. The aim of this study was to identify the presence of H. pylori in biopsy specimens from symptomatic patients by PCR. In addition, the rate of cagA, vacA, iceA1, and iceA2 virulence genes was determined. Materials and Methods. One hundred antral gastric biopsy specimens were collected during endoscopy from patients suffering from gastroduodenal symptoms. The samples were collected by the gastroenterologists in their own clinics in Ramallah, Palestine. DNA was extracted from the biopsies and subsequently used for PCR identification of H. pylori and the virulence genes using specific primers. Results. The rate of positive H. pylori in the collected biopsies was 44%. The rates of the virulence genes in this sample: cagA, vacA, iceA1, and iceA2 were 65.9%, 40.9%, 63.6%, and 84.1%, respectively. Conclusion. The iceA2 gene was the most frequent in this study. Much research is necessary to determine the presence of an association of this gene with gastric pathology. Variation in the rates of the iceA gene in different countries is a strong indication of its geographical distribution. This study would provide important information regarding the prevalence of virulence genes (vacA, cagA, iceA1, and iceA2) in H. pylori strains in the sample tested in this country. PMID:23691338

Essawi, Tamer; Hammoudeh, Wail; Sabri, Israr; Sweidan, Walid; Farraj, Mohammad A

2013-04-15

96

Helicobacter pylori typing as a tool for tracking human migration  

PubMed Central

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.

Yamaoka, Y.

2011-01-01

97

Avaliação do desempenho dos novos instrumentos de política de garantia de preços agrícolas de 2004 a 2007  

Microsoft Academic Search

O objetivo deste artigo é avaliar o desempenho dos instrumentos da Política de Garantia de Preços Agrícolas (PGPA), criados a partir de 2004, em termos de produtos e regiões. Os contratos de opção privada que começaram a ser criados a partir de 2004 possuem característica de transferir à iniciativa privada a responsabilidade de abastecer áreas previamente determinadas. O PEPRO -

Carlos Jose Caetano Bacha; Carlos Eduardo Caldarelli

2008-01-01

98

Avaliação dos Principais Déficits e Proposta de Tratamento da Aquisição Motora Rolar na Paralisia Cerebral  

Microsoft Academic Search

RESUMO Sabendo-se que crianças com paralisia cerebral apresentam atraso para as aquisições motoras, este estudo teve por objetivo verificar os principais déficits e propor um tratamento visando a aquisição motora rolar em pacientes com paralisia cerebral, com idade maior que seis meses que ainda não apresentavam esta função. A partir de uma pesquisa bibliográfica previamente realizada foi elaborado um guia

Elaine da Silva Peixoto; Carla Mazzitelli

99

SOBRE EL TRATAMIENTO DE GALIUM L. (RUBIACEAE) EN FLORA IBERICA  

Microsoft Academic Search

RESUMEN. Sobre el tratamiento de Galium L. (Rubiaceae) en Flora Iberica. El estudio taxonómico del género Galium para Flora Iberica ha revelado la existencia en el territorio de 51 especies y 14 subespecies. Éstas han sido agrupadas en 10 secciones, previamente descritas, reconociéndose para algunas de ellas nuevas series: Galium sect. Galium ser. Trichogaliopsis (Lange) Ortega-Olivencia & Devesa, Galium sect.

Ana ORTEGA-OLIVENCIA; Juan Antonio DEVESA

100

NAR-ANON E A ATRIBUIÇÃO DE EFEITOS DE SENTIDO À ORAÇÃO DA SERENIDADE  

Microsoft Academic Search

1 faz dela em suas reuniões. A oração é repetida ao fi nal de todos os encontros do grupo de forma ritualizada, quando os integrantes da irmandade, de mãos dadas, a proferem juntos. Pode-se dizer que a oração, naquelas condições de produção, a partir de um discurso previamente conhecido (ela não é de autoria do Grupo) e sendo enunciada pelos

Luciane Thomé Schröder

101

IMPACTO DE INSETICIDAS SOBRE A EMERGÊNCIA DE TRICHOGRAMMA PRETIOSUM, RILEY (HYMENOPTERA: TRICHOGRAMMATIDAE)  

Microsoft Academic Search

RESUMO - Estudou-se o efeito de cinco inseticidas (diflubenzuron, teflubenzuron, tebufenozide, triflumu- ron e abamectin + óleo mineral) no parasitismo e emergência de Trichogramma pretiosum, Riley, em ovos esterilizados de Anagasta kuehniella, Zeller. Num primeiro teste, ovos pulverizados com os ins e- ticidas foram submetidos ao parasitismo, e num se- gundo teste, ovos previamente parasitados durante 48h foram expostos à

AMÉRICO IORIO; CIOCIOLA JÚNIOR; LUCIANO DE CASTRO DINIZ; MAURÍCIO SÉRGIO ZACARIAS; ALESSANDRA RIBEIRO DE CARVALHO; AMÉRICO IORIO CIOCIOLA

102

High prevalence of virulent Helicobacter pylori strains in symptomatic Bulgarian patients.  

PubMed

The aim of the study was to evaluate the prevalence of main virulence genes in Helicobacter pylori strains from 116 patients with peptic ulcers (41 cases) and nonulcer diseases (75) by polymerase chain reaction (PCR) with pure cultures and to compare the results with those by multiplex PCR in 39 H. pylori-positive gastric biopsies in another center in Sofia, Bulgaria. Strain susceptibility to amoxicillin, metronidazole, and clarithromycin was determined by agar dilution method. By PCR with pure cultures, coinfections with multiple H. pylori strains were found in 8 (6.9%) patients who were excluded from the statistical analysis. Prevalence of toxigenic type vacA s1 was higher (91.7%) than that usually reported in Europe. cagA-positive genotype was detected in most (81.5%) strains, and almost all of them harbored vacA s1 genotype. Strains with cagA+/vacA s1a genotype were more common (80.6%) than the other genotypes (19.4%, P = 0.0001). The ulcer patients had more often virulent strains than the other patients (92.3% versus 75.4% for cagA+, 100.0% versus 87.0% for vacA s1, 100% versus 84.0% for vacA s1a, and 92.3% versus 73.9% for cagA+/vacA s1a, respectively). The prevalence of H. pylori virulence-associated genes was not associated with patients' sex and age or with the antibacterial resistance of strains. The most common H. pylori genotype was cagA+/vacA s1a. Similar prevalence of cagA-positive (82.1%), vacA s1 (97.4%), and cagA+/vacA s1 strains (79.5%) was found by multiplex PCR in gastric biopsies in the 2nd center. In conclusion, H. pylori strains with virulent genotypes are widespread in symptomatic Bulgarian patients. PMID:19631090

Boyanova, Lyudmila; Markovska, Rumiana; Yordanov, Daniel; Marina, Maya; Ivanova, Katusha; Panayotov, Stephan; Gergova, Galina; Mitov, Ivan

2009-08-01

103

Study of Helicobacter pylori genotype status in saliva, dental plaques, stool and gastric biopsy samples  

PubMed Central

AIM: To compare genotype of Helicobacter pylori (H. pylori) isolated from saliva, dental plaques, gastric biopsy, and stool of each patient in order to evaluate the mode of transmission of H. pylori infection. METHODS: This cross-sectional descriptive study was performed on 300 antral gastric biopsy, saliva, dental plaque and stool samples which were obtained from patients undergoing upper gastrointestinal tract endoscopy referred to endoscopy centre of Hajar hospital of Shahrekord, Iran from March 2010 to February 2011. Initially, H. pylori strains were identified by rapid urease test (RUT) and polymerase chain reaction (PCR) were applied to determine the presence of H. pylori (ureC) and for genotyping of voculating cytotoxin gene A (vacA) and cytotoxin associated gene A (cagA) genes in each specimen. Finally the data were analyzed by using statistical formulas such as Chi-square and Fisher’s exact tests to find any significant relationship between these genes and patient’s diseases. P < 0.05 was considered statistically significant. RESULTS: Of 300 gastric biopsy samples, 77.66% were confirmed to be H. pylori positive by PCR assay while this bacterium were detected in 10.72% of saliva, 71.67% of stool samples. We were not able to find it in dental plaque specimens. The prevalence of H. pylori was 90.47% among patients with peptic ulcer disease (PUD), 80% among patients with gastric cancer, and 74.13% among patients with none ulcer dyspepsia (NUD) by PCR assay. The evaluation of vacA and cagA genes showed 6 differences between gastric biopsy and saliva specimens and 11 differences between gastric and stool specimens. 94.42% of H. pylori positive specimens were cagA positive and all samples had amplified band both for vacA s and m regions. There was significant relationship between vacA s1a/m1a and PUD diseases (P = 0.04), s2/m2 genotype and NUD diseases (P = 0.05). No statically significant relationship was found between cagA status with clinical outcomes and vacA genotypes (P = 0.65). The evaluation of vacA and cagA genes showed 6 differences between gastric biopsy and saliva specimens and 11 differences between gastric and stool specimens. CONCLUSION: Regard to high similarity in genotype of H. pylori isolates from saliva, stomach and stool, this study support the idea which fecal- oral is the main route of H. pylori transmission and oral cavity may serve as a reservoir for H. pylori, however, remarkable genotype diversity among stomach, saliva and stool samples showed that more than one H. pylori genotype may exist in a same patient.

Momtaz, Hassan; Souod, Negar; Dabiri, Hossein; Sarshar, Meysam

2012-01-01

104

Toxigenic Helicobacter pylori induces changes in the gastric mucosal microcirculation in rats  

PubMed Central

Background and aims: One of the key components of inflammation is changes in vascular structure and function. This suggests that the microcirculation may be a key target of Helicobacter pylori released factors. It has previously been shown in vivo that pooled H pylori extracts from duodenal ulcer/gastritis patients induce platelet aggregation but no leucocyte activation within rat gastric mucosal microcirculation (GMMC). However, infection with strains associated with ulcer disease as compared with gastritis may exert greater effects on the microcirculation. This study used fluorescent in vivo microscopy to determine the acute effects of extracts of genotypically different H pylori strains on the GMMC. Methods: Three H pylori extracts, with different cagA and VacA toxigenic status, were individually administered to the gastric mucosa of anaesthetised Wistar rats. The mucosal surface was visualised via an incision made in the exteriorised stomach. Fluoroscein isothiocyanate conjugated to bovine serum albumin (FITC-BSA) or acridine orange was used to quantify macromolecular leak (MML) and leucocyte/platelet activity respectively for 120 minutes. Changes in capillary and post-capillary venule (PCV) diameters were also monitored. Results: The cagA+ VacA toxigenic strain 60190 induced significant and sustained MML by five minutes (p<0.01). Transient and less leakage was observed with its isogenic VacA? mutant and other non-toxigenic strains regardless of cagA status. Significant increases in leucocyte adhesion (p<0.05), platelet aggregation (p<0.05), and PCV vasoconstriction (p<0.05) were only observed with the cag A+ and toxigenic strain. Conclusion: Extracts of H pylori are capable of inducing marked disturbances within the rat GMMC. These disturbances seem to be dependent on the production of an active vacuolating cytotoxin. Varying effects on the GMMC may explain the clinically diverse outcomes associated with genotypically different strains.

Kalia, N; Bardhan, K D; Atherton, J C; Brown, N J

2002-01-01

105

Vacunación idiotípica en linfomas B de bajo grado: una nueva terapia antitumoral  

Microsoft Academic Search

Resumen  El idiotipo de la inmunoglobulina (Ig) de superficie de los linfomas B puede ser reconocido como antigénico por el sistema\\u000a inmune. Presentamos el resultado del primer ensayo de inmunización idiotípica en pacientes con linfoma folicular de bajo grado\\u000a que se ha llevado a cabo en Europa.\\u000a \\u000a Hemos vacunado a 7 pacientes, la mayoría tratados previamente con quimioterapia y trasplante autólogo.

José Rafael Cabrera; Yvelise Barrios; Rosa Yáñez; Manuel N. Fernández; Fernando Díaz de Espada

2001-01-01

106

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

PubMed Central

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.

Suhr-Jessen, Peter B.; Orias, Eduardo

1979-01-01

107

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

SciTech Connect

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.

Not Available

1993-12-31

108

Helicobacter pylori culture supernatant interferes with epidermal growth factor-activated signal transduction in human gastric KATO III cells.  

PubMed Central

The mechanisms by which Helicobacter pylori infection leads to gastroduodenal ulceration remain poorly understood. Previous studies have shown that H. pylori vacuolating cytotoxin (VacA) inhibits proliferation of gastric epithelial cells, which suggests that H pylori may interfere with gastric mucosal repair mechanisms. In this study, we investigated the effects of H. pylori broth culture supernatants on epidermal growth factor (EGF)-mediated signal transduction pathways in a gastric carcinoma cell line (KATO III). Exposure of these cells to EGF resulted in increased expression and phosphorylation of the EGF receptor (EGF-R), increased ERK2 activity and phosphorylation, and increased c-fos protein levels. Preincubation of cells with broth culture supernatant from VacA (+) H. pylori strain 60190 inhibited the capacity of EGF to induce each of these effects. In contrast, preincubation of cells with broth culture supernatant from an isogenic VacA-mutant strain (H. pylori 60190-v1) failed to inhibit the effects of EGF. These results suggest that the H. pylori vacuolating cytotoxin interferes with EGF-activated signal transduction pathways, which are known to be essential for cell proliferation and ulcer healing. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Pai, R.; Wyle, F. A.; Cover, T. L.; Itani, R. M.; Domek, M. J.; Tarnawski, A. S.

1998-01-01

109

Helicobacter pylori Disrupts Host Cell Membranes, Initiating a Repair Response and Cell Proliferation  

PubMed Central

Helicobacter pylori (H. pylori), the human stomach pathogen, lives on the inner surface of the stomach and causes chronic gastritis, peptic ulcer, and gastric cancer. Plasma membrane repair response is a matter of life and death for human cells against physical and biological damage. We here test the hypothesis that H. pylori also causes plasma membrane disruption injury, and that not only a membrane repair response but also a cell proliferation response are thereby activated. Vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA) have been considered to be major H. pylori virulence factors. Gastric cancer cells were infected with H. pylori wild type (vacA+/cagA+), single mutant (?vacA or ?cagA) or double mutant (?vacA/?cagA) strains and plasma membrane disruption events and consequent activation of membrane repair components monitored. H. pylori disrupts the host cell plasma membrane, allowing localized dye and extracellular Ca2+ influx. Ca2+-triggered members of the annexin family, A1 and A4, translocate, in response to injury, to the plasma membrane, and cell surface expression of an exocytotic maker of repair, LAMP-2, increases. Additional forms of plasma membrane disruption, unrelated to H. pylori exposure, also promote host cell proliferation. We propose that H. pylori activation of a plasma membrane repair is pro-proliferative. This study might therefore provide new insight into potential mechanisms of H. pylori-induced gastric carcinogenesis.

Lin, Li-Ling; Huang, Hsuan-Cheng; Ogihara, Satoshi; Wang, Jin-Town; Wu, Meng-Chuan; McNeil, Paul L.; Chen, Chiung-Nien; Juan, Hsueh-Fen

2012-01-01

110

PCR assay targeting virulence genes of Helicobacter pylori isolated from drinking water and clinical samples in Lahore metropolitan, Pakistan.  

PubMed

Helicobacter pylorus is considered for chronic gastritis, gastric ulcers and adenocarcinoma and its high infection rate is observed in overcrowded and lower socioeconomic groups in developing countries. This study was designed to identify the role of drinking water in the transmission and prevalence of H. pylori (HP). Selective HP medium was developed for enrichment and presumptive identification of H. pylori by urease, catalase and species specific 16S rRNA tests. The virulence genes (vacA 's' and 'm' regions and cagA) of H. pylori in 90 out of 225 H. pylori positive drinking water samples were present (40%). Ten out of 18 biopsies (55.55%) and 15 out of 50 vomiting fluids of gastric disease patients (30%) were also positive for virulence genes. Anti-H. pylori antibodies were also detected in 31 out of 50 patients' sera. The presence of virulence genes was also directly confirmed by hybridization studies using non-radioactive DNA probes of 16S rRNA, vacA and cagA genes. The presence of H. pylori in water is due to poor sanitary conditions, improper waste disposal and lack of public health education. PCR-based analysis and colony hybridization can be used for detection of H. pylori in clinical and environmental samples. PMID:21301128

Samra, Zahoor Qadir; Javaid, Umber; Ghafoor, Sadia; Batool, Aleeza; Dar, Nadia; Athar, Muhammad Amin

2011-03-01

111

Helicobacter pylori induced transactivation of SRE and AP-1 through the ERK signalling pathway in gastric cancer cells  

PubMed Central

BACKGROUND AND AIMS—Helicobacter pylori infection induces expression of proinflammatory cytokines such as interleukin (IL)-8 and tumour necrosis factor ? (TNF-?) in gastric mucosa, and their genes have AP-1 binding sites in the promoter region. c-Fos is important for transactivation of AP-1 which has SRE in the promoter region. We conducted this study to confirm H pylori induced transactivation of these binding sites.?METHODS—Transactivation of SRE and AP-1 was evaluated in human gastric cancer cells TMK1 and MKN45 by luciferase reporter assay in transient transfection. We compared the effects of coculture with four H pylori strains, a cag pathogenicity island (PAI) positive strain TN2, its isogenic vacA negative (TN2-?vacA) or cagE negative (TN2-?cagE) mutants, and a cag PAI negative clinical isolate T68. Phosphorylation of ERK1/2, JNK, and c-Jun was measured by immunoblot, induction of IL-8 secretion by ELISA, and the effects of MEK by inhibitor U0126.?RESULTS—Both SRE and AP-1 were transactivated by coculture with TN2. Although TN2-?vacA induced comparable transactivation, TN2-?cagE and T68 showed decreased transactivation of SRE (65% and 51%) and AP-1 (71% and 54%, respectively, of TN2). Heat killed TN2 or indirect contact using a permeable membrane inhibited transactivation. Levels of phosphorylated ERK1/2, JNK, and c-Jun were increased by coculture with TN2. MEK inhibitor U0126 reduced TN2 induced transactivation of SRE and AP1, as well as secretion of IL-8, by 83%, 87%, and 53%, respectively, of TN2.?CONCLUSIONS—Transactivation of SRE and AP-1, through ERK/MAPK and JNK/SAPK cascades, respectively, was found in gastric cancer cells cocultured with H pylori. Direct contact with viable bacteria possessing intact cag PAI is a prerequisite for the onset of intracellular signalling leading to AP-1 transactivation.???Keywords: Helicobacter pylori; SRE; AP-1; cag pathogenicity island PAI; gastric cancer

Mitsuno, Y; Yoshida, H; Maeda, S; Ogura, K; Hirata, Y; Kawabe, T; Shiratori, Y; Omata, M

2001-01-01

112

Analysis of iceA genotypes in South African Helicobacter pylori strains and relationship to clinically significant disease  

PubMed Central

BACKGROUND—South African Helicobacter pylori isolates are characterised by the universal presence of cagA but have differences in vacuolating cytotoxin gene (vacA) alleles which correlate with clinically significant disease. However, the candidate virulence marker gene iceA has not been investigated.?AIM—To characterise the genetic organisation and heterogeneity of iceA genotypes in different South African clinical isolates.?PATIENTS AND METHODS—We studied H pylori strains isolated from 86 dyspeptic patients (30 with peptic ulcer disease (PUD), 19 with distal gastric adenocarcinoma (GC), and 37 with non-erosive gastritis) for the presence of iceA1 or iceA2 genes, and for differences in the genetic organisation of iceA2 by polymerase chain reaction, Southern hybridisation analysis, and sequencing.?RESULTS—Genetic analysis of iceA1 demonstrated significant homology (92-95%) with the USA type strain 26695 and probably functions as a transcriptional regulator, while a novel variant (iceA2D') of iceA2 and marked differences in predicted protein secondary structure of the iceA2 protein were defined. iceA1 was detected in 68% and iceA2 in 80% of all clinical isolates. Although approximately 40% of patients had both strains, a higher prevalence (p< 0.01) of GC patients were infected with iceA1 isolates which were invariably vacA s1/iceA1 (p< 0.005 v gastritis). Isolates from PUD patients were distinguished by the structurally altered iceA2D variant (53%; p<0.03 v gastritis) while the iceA2C variant distinguished isolates from patients with gastritis alone (67%; p< 0.005 v PUD).?CONCLUSION—In this study, an association between iceA1 and GC was noted while differences in variants of iceA2 differentiated between PUD and gastritis alone. Combination analyses of iceA genotypes and vacA alleles supported these associations.???Keywords: adenocarcinoma; gastritis; Helicobacter pylori; iceA; peptic ulceration; protein prediction; sequencing; South Africa

Kidd, M; Peek, R; Lastovica, A; Israel, D; Kummer, A; Louw, J

2001-01-01

113

Potential implications of Helicobacter pylori-related neutrophil-activating protein.  

PubMed

Helicobacter pylori (H. pylori) virulence factors promote the release of various chemoattractants/inflammatory mediators, including mainly the neutrophil-attractant chemokine interleukin-8 and neutrophil-activating protein (NAP), involved in H. pylori-induced gastric pathologies. Co-administration of Chios mastic gum (CMG), which inhibits H. pylori NAP, with an H. pylori eradication regimen might add clinical benefits against H. pylori-related gastric pathologies, but possibly not CMG as main therapy. Although H. pylori NAP and other H. pylori-related cytotoxins [i.e., vaculating cytotoxin (VacA)] appear to play a major role in generating and maintaining the H. pylori-associated gastric inflammatory response and H. pylori NAP is a promising vaccine candidate against H. pylori infection (H. pylori-I), concerns regarding its potential drawbacks, particularly neurogenic ones, due to possible cross-mimicry, should be considered. Possible cross-mimicry between H. pylori NAP and/or bacterial aquaporin (AQP) and neural tissues may be associated with the anti-AQP-4 antibody-related neural damage in multiple sclerosis (MS)/neuromyelitis optica patients. Moreover, the sequence homology found between H. pylori VacA and human Na+/K+-ATPase A subunit suggests that antibodies to VacA involve ion channels in abaxonal Schwann cell plasmalemma resulting in demyelination in some patients. A series of factors have been implicated in inducing blood-brain barrier (BBB) disruption, including inflammatory mediators (e.g., cytokines and chemokines induced by H. pylori-I) and oxidative stress. BBB disruption permits access of AQP4-specific antibodies and T lymphocytes to the central nervous system, thereby playing a major role in multiple sclerosis pathogenesis. Relative studies show a strong association between H. pylori-I and MS. H. pylori-I induces humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mimicry), cross-react with components of nerves, thereby contributing and perpetuating neural tissue damage. Finally, H. pylori NAP also plays a possible pathogenetic role in both gastric and colon oncogenesis. PMID:22346256

Kountouras, Jannis; Zavos, Christos; Deretzi, Georgia; Gavalas, Emmanuel; Chatzopoulos, Dimitrios; Katsinelos, Panagiotis; Tsiaousi, Elena; Gagalis, Stergios; Polyzos, Stergios A; Venizelos, Ioannis

2012-02-01

114

Potential implications of Helicobacter pylori-related neutrophil-activating protein  

PubMed Central

Helicobacter pylori (H. pylori) virulence factors promote the release of various chemoattractants/inflammatory mediators, including mainly the neutrophil-attractant chemokine interleukin-8 and neutrophil-activating protein (NAP), involved in H. pylori-induced gastric pathologies. Co-administration of Chios mastic gum (CMG), which inhibits H. pylori NAP, with an H. pylori eradication regimen might add clinical benefits against H. pylori-related gastric pathologies, but possibly not CMG as main therapy. Although H. pylori NAP and other H. pylori-related cytotoxins [i.e., vaculating cytotoxin (VacA)] appear to play a major role in generating and maintaining the H. pylori-associated gastric inflammatory response and H. pylori NAP is a promising vaccine candidate against H. pylori infection (H. pylori-I), concerns regarding its potential drawbacks, particularly neurogenic ones, due to possible cross-mimicry, should be considered. Possible cross-mimicry between H. pylori NAP and/or bacterial aquaporin (AQP) and neural tissues may be associated with the anti-AQP-4 antibody-related neural damage in multiple sclerosis (MS)/neuromyelitis optica patients. Moreover, the sequence homology found between H. pylori VacA and human Na+/K+-ATPase A subunit suggests that antibodies to VacA involve ion channels in abaxonal Schwann cell plasmalemma resulting in demyelination in some patients. A series of factors have been implicated in inducing blood-brain barrier (BBB) disruption, including inflammatory mediators (e.g., cytokines and chemokines induced by H. pylori-I) and oxidative stress. BBB disruption permits access of AQP4-specific antibodies and T lymphocytes to the central nervous system, thereby playing a major role in multiple sclerosis pathogenesis. Relative studies show a strong association between H. pylori-I and MS. H. pylori-I induces humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mimicry), cross-react with components of nerves, thereby contributing and perpetuating neural tissue damage. Finally, H. pylori NAP also plays a possible pathogenetic role in both gastric and colon oncogenesis.

Kountouras, Jannis; Zavos, Christos; Deretzi, Georgia; Gavalas, Emmanuel; Chatzopoulos, Dimitrios; Katsinelos, Panagiotis; Tsiaousi, Elena; Gagalis, Stergios; Polyzos, Stergios A; Venizelos, Ioannis

2012-01-01

115

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

PubMed Central

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.

Filipec Kanizaj, Tajana; Katicic, Miroslava; Presecki, Vladimir; Gasparov, Slavko; Colic Cvrlje, Vesna; Kolaric, Branko; Mrzljak, Anna

2009-01-01

116

Faulting evidence of isostatic uplift in the Rincon Mountains metamorphic core complex: An image processing analysis  

NASA Astrophysics Data System (ADS)

This study focuses on the applications of remote sensing techniques and digital analysis to characterizing of tectonic features of the Rincon Mountains metamorphic core complex. Data included Landsat Thematic Mapper (TM) images, digital elevation models (DEM), and digital orthophoto quadrangle quads (DOQQ). The main findings in this study are two nearly orthogonal systems of structures that have never been reported in the Rincon Mountains. The first system, a penetrative faulting system of the footwall rocks, trends N10--30°W. Similar structures identified in other metamorphic core complexes. The second system trends N60--70°E, and has only been alluded indirectly in the literature of metamorphic core complexes. The structures pervade mylonites in Tanque Verde Mountain, Mica Mountain, and the Rincon Peak area. As measured on the imagery, spacing between the N10--30°W lineaments ranges from ˜0.5 to 2 km, and from 0.25 to 1 km for the N60--70°E system. Field inspection reveals that the N10--30°W trending system, are high-angle normal faults dipping mainly to the west. One of the main faults, named here the Cabeza de Vaca fault, has a polished, planar, striated and grooved surface with slickenlines indicating pure normal dip-slip movement (N10°W, 83°SW; slickensides rake 85°SW). The Cabeza de Vaca fault is the eastern boundary of a 2 km-wide graben, with displacement as great as 400 meters. The N10--30°W faults are syn- to post-mylonitic, high-angle normal faults that formed during isostatic uplift of the Rincon core complex during mid-Tertiary time. This interpretation is based on previous works, which report similar fault patterns in other metamorphic core complexes. Faults trending N20--30°W, shape the east flank of Mica Mountain. These faults, on the back dipping mylonitic zone, dip east and may represent late-stage antithetic shear zones. The Cabeza de Vaca fault and the back dipping antithetic faults accommodate as much as 65% of the extension due to doming of the core complex. The N60--70°E structures, not verified as a fault system, are a joint system pervading the footwall rocks of the metamorphic core complex. This system is less systematic. Spacing varies from 0.25 to 1 km. Both systems control the drainage of the mountains.

Rodriguez-Guerra, Edna Patricia

117

[Evaluation of Western Blot method for the detection of antibodies to Helicobacter pylori antigens in patients with gastric carcinoma and cases with epigastric complaints].  

PubMed

Helicobacter pylori proteins CagA (cytotoxin-associated gene A) and VacA (vacuolating cytotoxin A) are among the virulence factors of this species. CagA gene carrying H. pylori strains are particularly associated with gastric adenocarsinoma. This study was conducted to evaluate Western Blot (WB) method to determine specific H. pylori antibodies in a group of patients with gastric cancer and in a control group with no malignancy. A total of 99 patients with gastric cancer (94 adenocarcinoma, 2 adenosquamous cell carcinoma, 3 non-Hodgkin lymphoma) and 150 control cases with epigastric complaints such as nausea, vomiting, diarrhea, gastroesophageal reflux and abdominal pain, were included to the study. H. pylori IgG-ELISA was positive in all study (mean age: 56.7 +/- 1.2 years, 62 male) and control (mean age: 24.2 +/- 1.3 years, 64 male) patients. Specific antibodies against CagA, VacA, OMP (outer membrane protein)-67, urease-A, urease-B, HSP (heat shock protein) and flagellin antigens determined by a commercial WB-based kit (RIDA Blot Helicobacter, R-Biopharm GmbH, Germany). Interestingly, no anti-VacA positivity was detected in none of the patient and control groups. The positivity rates for H. pylori CagA, OMP-67, urease A, urease-B, flagellin and HSP specific antibodies were as 78%, 54%, 37%, 60%, 53% and 82% in the gastric cancer group and 85%, 71%, 55%, 43%, 61% and 75% in the control group, respectively. There was no statistically significant difference (p > 0.05) between gastric carcinoma and control groups in terms of CagA, HSP and flagellin antibodies (p > 0.05). On the other hand, a statistically significant difference was found between the 2 groups in terms of urease-A, urease-B and OMP-67 (p < 0.01). These results suggested that this test should be assessed again by the manufacturer for its detection power directed towards specific H. pylori antibodies, especially for Vac-A. Further molecular and clinical studies are necessary to determine the factors that affect H. pylori virulence and disease prognosis. PMID:20455395

Güdücüo?lu, Hüseyin; Berkta?, Mustafa; Bozkurt, Hamza; Toka Ozer, Türkan; Bulut, Gülay; Oztürk, Oznur; Ilhan, Mahmut

2010-01-01

118

Iron trafficking system in Helicobacter pylori.  

PubMed

Helicobacter pylori infections are closely associated with peptic ulcers, gastric malignancy and iron deficiency anemia. Iron is essential for almost all living organisms and the investigation of iron uptake and trafficking system is thus important to understand the pathological roles of H. pylori. Up to now, the iron trafficking system of H. pylori is not yet fully clear and merits further efforts in this regards. The available information about iron uptake and regulation has been discussed in this concise review, such as FeoB in ferrous transportation, FrpB2 in hemoglobin uptake, HugZ in heme processing, virulence factors (VacA and CagA) in transferrin utilization, Pfr and NapA in iron storage and Fur in iron regulation. The identified iron trafficking system will help us to understand the pathological roles of H. pylori in the various gastric diseases and iron deficiency anemia and stimulates further development of effective anti-bacterial drugs. PMID:22127376

Ge, Ruiguang; Sun, Xuesong

2011-11-30

119

Antimicrobial resistance and characterization of Helicobacter pylori strains isolated from Mexican adults with clinical outcome.  

PubMed

Eradication of Helicobacter pylori infection in Mexico is of great importance due to the elevated seroprevalence, however, there is yet very little information about antibiotic resistance rates in H. pylori isolates in our country. We analyzed susceptibility to three antimicrobials used in therapy of 49 H. pylori strains isolated from patients with active chronic gastritis, active chronic gastritis with lymphoid follicles, intestinal metaplasia and gastric cancer. All isolated strains were susceptible to amoxicillin, 28 (58%) were resistant to metronidazole and 2 (4%) were resistant to both clarithromycin and metronidazole. Sequence analysis of the 23S rRNA of the two clarithromycin-resistant strains showed the A2142G mutation in one and A2143G and T2182C mutations in the other. Metronidazole resistance was associated with cagA negative strains with a frequency of 82% (9/11). No significant correlation was found between vacA s/m alleles and metronidazole resistance. PMID:16038520

Chihu, L; Ayala, G; Mohar, A; Hernández, A; Herrera-Goepfert, R; Fierros, G; González-Márquez, H; Silva, J

2005-06-01

120

The Wittliff Collection  

NSDL National Science Digital Library

Founded at Texas State University-San Marcos by Austin screenwriter and photographer Bill Wittliff and his wife Sally, the Wittliff Collections bring together "the Southwest's literature, film, and music." Visitors to the website can share in all of these cultural wonders, including materials from the Southwestern Writers Collection and several extensive photography collections. First-time visitors should head on over to "The Collections" area to take in the travel narrative of Cabeza de Vaca, found in the Southwestern Writers Collection "Research and Archives", and a wonderful tribute to the TV series and book, "Lonesome Dove". Moving on, the "Exhibitions & Events" area contains information about their various traveling exhibits, events, and writer talks. The site is rounded out by an online gift store and more details about their book series and anthologies of Southwestern writers.

121

Host-Interactive Genes in Amerindian Helicobacter pylori Diverge from Their Old World Homologs and Mediate Inflammatory Responses? †  

PubMed Central

Helicobacter pylori is the dominant member of the gastric microbiota and has been associated with an increased risk of gastric cancer and peptic ulcers in adults. H. pylori populations have migrated and diverged with human populations, and health effects vary. Here, we describe the whole genome of the cag-positive strain V225d, cultured from a Venezuelan Piaroa Amerindian subject. To gain insight into the evolution and host adaptation of this bacterium, we undertook comparative H. pylori genomic analyses. A robust multiprotein phylogenetic tree reflects the major human migration out of Africa, across Europe, through Asia, and into the New World, placing Amerindian H. pylori as a particularly close sister group to East Asian H. pylori. In contrast, phylogenetic analysis of the host-interactive genes vacA and cagA shows substantial divergence of Amerindian from Old World forms and indicates new genotypes (e.g., VacA m3) involving these loci. Despite deletions in CagA EPIYA and CRPIA domains, V225d stimulates interleukin-8 secretion and the hummingbird phenotype in AGS cells. However, following a 33-week passage in the mouse stomach, these phenotypes were lost in isolate V225-RE, which had a 15-kb deletion in the cag pathogenicity island that truncated CagA and eliminated some of the type IV secretion system genes. Thus, the unusual V225d cag architecture was fully functional via conserved elements, but the natural deletion of 13 cag pathogenicity island genes and the truncation of CagA impaired the ability to induce inflammation.

Mane, S. P.; Dominguez-Bello, M. G.; Blaser, M. J.; Sobral, B. W.; Hontecillas, R.; Skoneczka, J.; Mohapatra, S. K.; Crasta, O. R.; Evans, C.; Modise, T.; Shallom, S.; Shukla, M.; Varon, C.; Megraud, F.; Maldonado-Contreras, A. L.; Williams, K. P.; Bassaganya-Riera, J.

2010-01-01

122

Detection of Helicobacter pylori in oropharyngeal lymphatic tissue with real-time PCR and assessment of its carcinogenic potential.  

PubMed

Helicobacter pylori (HP) is considered a major gastric pathogen with oncogenic potential. The aim of this study was to determine whether HP is present in oropharyngeal lymphoid tissue and whether oropharyngeal HP strains carry virulence factor genes known to be involved in gastric carcinogenesis. The study included 104 subjects (41 patients with tonsillar carcinoma, 38 with chronic tonsillitis and 25 with obstructive sleep apnoea syndrome-OSAS). Detection of specific serum anti-HP antibodies was performed with an ELISA. The presence of HP in tissue was determined by culture and real-time PCR. Detection of virulence factors genes was also performed. Specific antibodies were found in 78.05 % of tumour cases, 34.21 % of chronic tonsillitis cases, and 72.0 % of OSAS cases. The presence of HP in the tissue was detected in 73.91 % of tonsillar tumours, 70.0 % of tonsillitis cases, and 69.23 % of OSAS specimens. The results of the virulence factor gene analysis showed the majority of the s1b (52.4 %) and m2 (59.5 %) alleles of vacA gene and limited abundance of cagA gene (12.5 %). Results confirm that HP may colonise oropharyngeal lymphoid tissue. Oropharyngeal HP colonisation was frequently found in the oropharyngeal cancer group and in patients with benign oropharyngeal diseases. A virulence factor gene analysis showed differences from the predominant strains most commonly found in the stomach. The strains obtained from the oropharynx differed primarily by the lower abundance of the cagA gene and carried the less virulent vacA gene allele combination. PMID:23744180

Lukeš, Petr; Pavlík, Emil; Potuznikova, Bela; Nartova, Eva; Foltynova, Eva; Plzak, Jan; Katra, Rami; Sterzl, Ivan; Bartunkova, Jirina; Betka, Jan; Astl, Jaromir

2013-06-01

123

Helicobacter Pylori Promotes the Expression of Kr?ppel-Like Factor 5, a Mediator of Carcinogenesis, In Vitro and In Vivo  

PubMed Central

Helicobacter pylori is the strongest known risk factor for the development of gastric adenocarcinoma. H. pylori expresses a repertoire of virulence factors that increase gastric cancer risk, including the cag pathogenicity island and the vacuolating cytotoxin (VacA). One host element that promotes carcinogenesis within the gastrointestinal tract is Krüppel-like factor 5 (KLF5), a transcription factor that mediates key cellular functions. To define the role of KLF5 within the context of H. pylori-induced inflammation and injury, human gastric epithelial cells were co-cultured with the wild-type cag+ H. pylori strain 60190. KLF5 expression was significantly upregulated following co-culture with H. pylori, but increased expression was independent of the cag island or VacA. To translate these findings into an in vivo model, C57BL/6 mice were challenged with the wild-type rodent-adapted cag+ H. pylori strain PMSS1 or a PMSS1 cagE? isogenic mutant. Similar to findings in vitro, KLF5 staining was significantly enhanced in gastric epithelium of H. pylori-infected compared to uninfected mice and this was independent of the cag island. Flow cytometry revealed that the majority of KLF5+ cells also stained positively for the stem cell marker, Lrig1, and KLF5+/Lrig1+ cells were significantly increased in H. pylori-infected versus uninfected tissue. To extend these results into the natural niche of this pathogen, levels of KLF5 expression were assessed in human gastric biopsies isolated from patients with or without premalignant lesions. Levels of KLF5 expression increased in parallel with advancing stages of neoplastic progression, being significantly elevated in gastritis, intestinal metaplasia, and dysplasia compared to normal gastric tissue. These results indicate that H. pylori induces expression of KLF5 in gastric epithelial cells in vitro and in vivo, and that the degree of KLF5 expression parallels the severity of premalignant lesions in human gastric carcinogenesis.

Noto, Jennifer M.; Khizanishvili, Tinatin; Chaturvedi, Rupesh; Piazuelo, M. Blanca; Romero-Gallo, Judith; Delgado, Alberto G.; Khurana, Shradha S.; Sierra, Johanna C.; Krishna, Uma S.; Suarez, Giovanni; Powell, Anne E.; Goldenring, James R.; Coffey, Robert J.; Yang, Vincent W.; Correa, Pelayo; Mills, Jason C.; Wilson, Keith T.; Peek, Richard M.

2013-01-01

124

Helicobacter pylori promotes the expression of Krüppel-like factor 5, a mediator of carcinogenesis, in vitro and in vivo.  

PubMed

Helicobacter pylori is the strongest known risk factor for the development of gastric adenocarcinoma. H. pylori expresses a repertoire of virulence factors that increase gastric cancer risk, including the cag pathogenicity island and the vacuolating cytotoxin (VacA). One host element that promotes carcinogenesis within the gastrointestinal tract is Krüppel-like factor 5 (KLF5), a transcription factor that mediates key cellular functions. To define the role of KLF5 within the context of H. pylori-induced inflammation and injury, human gastric epithelial cells were co-cultured with the wild-type cag(+) H. pylori strain 60190. KLF5 expression was significantly upregulated following co-culture with H. pylori, but increased expression was independent of the cag island or VacA. To translate these findings into an in vivo model, C57BL/6 mice were challenged with the wild-type rodent-adapted cag(+) H. pylori strain PMSS1 or a PMSS1 cagE(-) isogenic mutant. Similar to findings in vitro, KLF5 staining was significantly enhanced in gastric epithelium of H. pylori-infected compared to uninfected mice and this was independent of the cag island. Flow cytometry revealed that the majority of KLF5(+) cells also stained positively for the stem cell marker, Lrig1, and KLF5(+)/Lrig1(+) cells were significantly increased in H. pylori-infected versus uninfected tissue. To extend these results into the natural niche of this pathogen, levels of KLF5 expression were assessed in human gastric biopsies isolated from patients with or without premalignant lesions. Levels of KLF5 expression increased in parallel with advancing stages of neoplastic progression, being significantly elevated in gastritis, intestinal metaplasia, and dysplasia compared to normal gastric tissue. These results indicate that H. pylori induces expression of KLF5 in gastric epithelial cells in vitro and in vivo, and that the degree of KLF5 expression parallels the severity of premalignant lesions in human gastric carcinogenesis. PMID:23372710

Noto, Jennifer M; Khizanishvili, Tinatin; Chaturvedi, Rupesh; Piazuelo, M Blanca; Romero-Gallo, Judith; Delgado, Alberto G; Khurana, Shradha S; Sierra, Johanna C; Krishna, Uma S; Suarez, Giovanni; Powell, Anne E; Goldenring, James R; Coffey, Robert J; Yang, Vincent W; Correa, Pelayo; Mills, Jason C; Wilson, Keith T; Peek, Richard M

2013-01-23

125

Helicobacter pylori immune escape is mediated by dendritic cell-induced Treg skewing and Th17 suppression in mice  

PubMed Central

Background & Aims Helicobacter pylori infection increases gastric Treg response, which may contribute to H pylori immune escape. We hypothesize that H pylori directs Treg skewing by way of dendritic cells and thus inhibits Th17 immunity. Methods Two-photon microscopy was used to locate dendritic cells in gastric lamina propria of mice. The induction of Th17 and Treg responses by bacteria-pulsed murine bone marrow–derived dendritic cells was analyzed by cytokine production and stimulation of T cell proliferation. The effect of VacA, CagA, TGF-?, and IL-10 on Th17/Treg balance was assessed. The in vivo significance of Tregs on the H pylori–specific Th17 response and H pylori density was determined using anti-CD25 neutralizing antibodies to deplete Tregs in mice. Results We showed that mucosal CD11c+ dendritic cells are located near the surface of normal gastric epithelium and their number increased after H pylori infection. Study of the direct interaction of dendritic cells with H pylori revealed a Treg-skewed response. The Treg skewing was independent of H pylori VacA and CagA and dependent on TGF-? and IL-10. In vivo Treg skewing by adoptive transfer of H pylori–pulsed DCs reduces the ratio of gastric IL-17/Foxp3 mRNA expressions. The depletion of CD25+ Tregs results in early reduction of H pylori density, which is correlated with enhanced peripheral H pylori–specific Th17, but not Th1, response. Conclusions Overall, our study indicates that H pylori alters the DC-polarized Th17/Treg balance towards a Treg-biased response, which suppresses the effective induction of H pylori–specific Th17 immunity.

Kao, John Y.; Zhang, Min; Miller, Mark J.; Mills, Jason C.; Wang, Baomei; Liu, Maochang; Eaton, Kathyn A.; Zou, Weiping; Berndt, Bradford E.; Cole, Tyler S.; Takeuchi, Tomomi; Owyang, Stephanie Y.; Luther, Jay

2009-01-01

126

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

USGS Publications Warehouse

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.

Soler-Lopez, Luis R.

2008-01-01

127

Screening Helicobacter pylori genes induced during infection of mouse stomachs  

PubMed Central

AIM: To investigate the effect of in vivo environment on gene expression in Helicobacter pylori (H. pylori) as it relates to its survival in the host. METHODS: In vivo expression technology (IVET) systems are used to identify microbial virulence genes. We modified the IVET-transcriptional fusion vector, pIVET8, which uses antibiotic resistance as the basis for selection of candidate genes in host tissues to develop two unique IVET-promoter-screening vectors, pIVET11 and pIVET12. Our novel IVET systems were developed by the fusion of random Sau3A DNA fragments of H. pylori and a tandem-reporter system of chloramphenicol acetyltransferase and beta-galactosidase. Additionally, each vector contains a kanamycin resistance gene. We used a mouse macrophage cell line, RAW 264.7 and mice, as selective media to identify specific genes that H. pylori expresses in vivo. Gene expression studies were conducted by infecting RAW 264.7 cells with H. pylori. This was followed by real time polymerase chain reaction (PCR) analysis to determine the relative expression levels of in vivo induced genes. RESULTS: In this study, we have identified 31 in vivo induced (ivi) genes in the initial screens. These 31 genes belong to several functional gene families, including several well-known virulence factors that are expressed by the bacterium in infected mouse stomachs. Virulence factors, vacA and cagA, were found in this screen and are known to play important roles in H. pylori infection, colonization and pathogenesis. Their detection validates the efficacy of these screening systems. Some of the identified ivi genes have already been implicated to play an important role in the pathogenesis of H. pylori and other bacterial pathogens such as Escherichia coli and Vibrio cholerae. Transcription profiles of all ivi genes were confirmed by real time PCR analysis of H. pylori RNA isolated from H. pylori infected RAW 264.7 macrophages. We compared the expression profile of H. pylori and RAW 264.7 coculture with that of H. pylori only. Some genes such as cagA, vacA, lpxC, murI, tlpC, trxB, sodB, tnpB, pgi, rbfA and infB showed a 2-20 fold upregulation. Statistically significant upregulation was obtained for all the above mentioned genes (P < 0.05). tlpC, cagA, vacA, sodB, rbfA, infB, tnpB, lpxC and murI were also significantly upregulated (P < 0.01). These data suggest a strong correlation between results obtained in vitro in the macrophage cell line and in the intact animal. CONCLUSION: The positive identification of these genes demonstrates that our IVET systems are powerful tools for studying H. pylori gene expression in the host environment.

Singh, Aparna; Hodgson, Nathaniel; Yan, Ming; Joo, Jungsoo; Gu, Lei; Sang, Hong; Gregory-Bryson, Emmalena; Wood, William G; Ni, Yisheng; Smith, Kimberly; Jackson, Sharon H; Coleman, William G

2012-01-01

128

H. pylori infection and genotyping in patients undergoing upper endoscopy at inner city hospitals.  

PubMed

Kings County Hospital (KCH), and St. John's Episcopal Hospital (SJH) are inner-city hospitals in New York City serving predominantly minority populations. Staten Island University Hospital (SIUH) serves a predominantly middle-class Caucasian population. We examined H. pylori (HP) infection in patients undergoing upper endoscopy at these hospitals. Two gastric biopsies were obtained from each patient. One biopsy was examined by histology or the rapid urease test for the presence of HP. The other was subjected to analysis by PCR to detect HP DNA and to identify putative HP virulence factors. Of 200 subjects, 54% were African-American, 10% were Hispanic, and 36% were Caucasian. HP infection rates in African-American, Hispanic, and Caucasian patients were 43%, 20%, and 11%, respectively. Many of the African-American patients are recent immigrants from the Caribbean Islands. In these patients, an inverse relationship was observed between HP infection and the number of years living in the United States. Higher levels of HP infection were observed in patients with duodenitis and peptic ulcer disease. With respect to HP virulence factors, the vacA s1b and m1 alleles, as well as the iceA2 allele were the predominant alleles expressed in HP-positive samples obtained from African-Americans. The cagA gene was detected in 81% of HP-positive samples. However, CagA positivity was not related to any specific gastrointestinal disorder. Our findings indicate that among several ethnic groups served by three hospitals, African-American patients have the highest rate of HP infection. Moreover, in AfricanAmerican patients undergoing endoscopy: (1) HP infection was inversely related to the number of years the patients have been living in the USA; (2) HP infection rates were higher in patients diagnosed with duodenitis and peptic ulcer disease versus other disorders; (3) expression of the CagA gene was not associated with any specific gastroduodenal disorder; and (4) there was little allelic heterogeneity with respect to VacA and IceA subtypes. These findings suggest that inner-city African-Americans are more likely to be infected with HP and suffer from more serious gastroduodenal disorders than other ethnic groups. PMID:12141819

Straus, E W; Patel, H; Chang, J; Gupta, R M; Sottile, V; Scirica, J; Tarabay, G; Iyer, S; Samuel, S; Raffaniello, R D

2002-07-01

129

Helicobacter pylori upregulates expression of epidermal growth factor-related peptides, but inhibits their proliferative effect in MKN 28 gastric mucosal cells.  

PubMed Central

Acute exposure to Helicobacter pylori causes cell damage and impairs the processes of cell migration and proliferation in cultured gastric mucosal cells in vitro. EGF-related growth factors play a major role in protecting gastric mucosa against injury, and are involved in the process of gastric mucosal healing. We therefore studied the acute effect of H. pylori on expression of EGF-related growth factors and the proliferative response to these factors in gastric mucosal cells (MKN 28) derived from gastric adenocarcinoma. Exposure of MKN 28 cells to H. pylori suspensions or broth culture filtrates upregulated mRNA expression of amphiregulin (AR) and heparin-binding EGF-like growth factor (HB-EGF), but not TGFalpha. This effect was specifically related to H. pylori since it was not observed with E. coli, and was independent of VacA, CagA, PicA, PicB, or ammonia. Moreover, H. pylori broth culture filtrates stimulated extracellular release of AR and HB-EGF protein by MKN 28 cells. AR and HB-EGF dose-dependently and significantly stimulated proliferation of MKN 28 cells in the absence of H. pylori filtrate, but had no effect in the presence of H. pylori broth culture filtrates. Inhibition of AR- or HB-EGF- induced stimulation of cell growth was not mediated by downregulation of the EGF receptor since EGF receptor protein levels, EGF binding affinity, number of specific binding sites for EGF, or HB-EGF- or AR-dependent tyrosine phosphorylation of the EGF receptor were not significantly altered by incubation with H. pylori broth culture filtrates. Increased expression of AR and HB-EGF were mediated by an H. pylori factor > 12 kD in size, whereas antiproliferative effects were mediated by both VacA and a factor < 12 kD in size. We conclude that H. pylori increases mucosal generation of EGF-related peptides, but in this acute experimental model, this event is not able to counteract the inhibitory effect of H. pylori on cell growth. The inhibitory effect of H. pylori on the reparative events mediated by EGF-related growth factors might play a role in the pathogenesis of H. pylori-induced gastroduodenal injury.

Romano, M; Ricci, V; Di Popolo, A; Sommi, P; Del Vecchio Blanco, C; Bruni, C B; Ventura, U; Cover, T L; Blaser, M J; Coffey, R J; Zarrilli, R

1998-01-01

130

Recent Contractile Deformation in the Forearc of Southern Peru: A Geomorphologic Analysis And 10Be Surface Exposure Ages  

NASA Astrophysics Data System (ADS)

The style, amount, and timing of deformation along the margins of the Altiplano are important components of our working model of the formation and maintenance of this high elevation plateau. While much of the convergence- related shortening is accommodated along the eastern margin in the Subandean fold and thrust belt, a significant amount of uplift and crustal thickening has occurred in the western margin during the past ~20 Myr. In addition to ancient uplift and deformation, various styles and amounts of Recent deformation that reflect the current lithospheric state of stress have been documented within the forearc. Some of the first order variables that affect the state of stress and therefore the style of deformation within the forearc of the western margin include: 1) the variable dip of the subducting slab along the South American margin, 2) the orientation of convergence relative to the margin, and 3) the subduction of aseismic ridges (e.g., Nazca Ridge). Other potential influences on the state of stress include addition of material to the western margin through lower-mid crustal flow, subduction erosion, and magmatic additions. In southern Peru, previously documented active deformation in the forearc includes coastal normal faults trending perpendicular to the trench, and transform faults oriented parallel to the trench, including the left-lateral Incapucio fault system, of the Precordillera. Our new field mapping and geochronologic studies in the Longitudinal Basin and Precordillera of southern Peru reveal recent contractile deformation along structures trending sub-parallel to the trench. Here, a southwest propagating anticline related to a blind thrust deflects the active stream channels within the Pampa Cabeza de Vaca region. Incision along the active drainages is localized to areas near active structures and has produced strath terraces that provide datable geomorphologic markers to quantify incision rates and constrain the timing of deformation. Cosmogenic 10Be surface exposure ages from a set of three distinct abandoned terraces in the Pampa Cabeza de Vaca region yield ages ranging from ~35-550ky and incision rates of ~0.04-0.09mm/yr. Thus, the contractile deformation within this region has been active for at least the last 500ky and is plausibly presently active. The documentation of recent contractile deformation within the forearc of southern Peru stylistically contrasts with previously held view active deformation in this region is dominated by extensional topographic collapse. Moreover, active shortening within the Peruvian forearc bears on our models of how the Altiplano plateau is currently being maintained along the western margin. Indeed, by identifying and quantifying active deformation within the Peruvian forearc, we can begin to address the potential links between surface processes related to climate and active tectonics, and the dynamics of the lithosphere.

Hall, S.; Farber, D. L.; Audin, L.; Finkel, R.

2007-12-01

131

Diagn?stico diferencial en la encefalitis por anticuerpos contra el receptor NMDA  

PubMed Central

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.

Gonzalez-Valcarcel, J.; Rosenfeld, M.R.; Dalmau, J.

2011-01-01

132

Dinámica global en galaxias elípticas  

NASA Astrophysics Data System (ADS)

Con el propósito de determinar propiedades dinámicas globales en sistemas triaxiales no integrables, utilizamos una nueva herramienta conocida como ``Mean Exponential Growth factor of Nearby Orbits'' (MEGNO), introducida por Cincotta y Simó (2000). Esta técnica no sólo resulta eficiente para investigar ambas componentes del espacio fase, regular y caótica, sino que también, provee una medida de la hiperbolicidad en el dominio caótico que coincide con la dada por el Lyapunov Characteristic Number (LCN). Previamente este método ha sido aplicado al estudio de modelos simples, y últimamente en el campo de la Mecánica Celeste, al estudio de sistemas planetarios extrasolares. En esta presentación, ilustraremos algunas de las propiedades más importantes del MEGNO, aplic& acute;andolo al potencial tridimensional de Stäckel perturbado.

Pérez, M. J.; Cincotta, P. M.; Giordano, C. M.

133

Phylogeographic origin of Helicobacter pylori determines host-adaptive responses upon coculture with gastric epithelial cells.  

PubMed

While Helicobacter pylori infects over 50% of the world's population, the mechanisms involved in the development of gastric disease are not fully understood. Bacterial, host, and environmental factors play a role in disease outcome. To investigate the role of bacterial factors in H. pylori pathogenesis, global gene expression of six H. pylori isolates was analyzed during coculture with gastric epithelial cells. Clustering analysis of six Colombian clinical isolates from a region with low gastric cancer risk and a region with high gastric cancer risk segregated strains based on their phylogeographic origin. One hundred forty-six genes had increased expression in European strains, while 350 genes had increased expression in African strains. Differential expression was observed in genes associated with motility, pathogenicity, and other adaptations to the host environment. European strains had greater expression of the virulence factors cagA, vacA, and babB and were associated with increased gastric histologic lesions in patients. In AGS cells, European strains promoted significantly higher interleukin-8 (IL-8) expression than did African strains. African strains significantly induced apoptosis, whereas only one European strain significantly induced apoptosis. Our data suggest that gene expression profiles of clinical isolates can discriminate strains by phylogeographic origin and that these profiles are associated with changes in expression of the proinflammatory and protumorigenic cytokine IL-8 and levels of apoptosis in host epithelial cells. These findings support the hypothesis that bacterial factors determined by the phylogeographic origin of H. pylori strains may promote increased gastric disease. PMID:23630959

Sheh, Alexander; Chaturvedi, Rupesh; Merrell, D Scott; Correa, Pelayo; Wilson, Keith T; Fox, James G

2013-04-29

134

Helicobacter pylori's virulence and infection persistence define pre-eclampsia complicated by fetal growth retardation  

PubMed Central

AIM: To better understand the pathogenic role of Helicobacter pylori (H. pylori) in pre-eclampsia (PE), and whether it is associated or not with fetal growth retardation (FGR). METHODS: Maternal blood samples were collected from 62 consecutive pregnant women with a diagnosis of PE and/or FGR, and from 49 women with uneventful pregnancies (controls). Serum samples were evaluated by immunoblot assay for presence of specific antibodies against H. pylori antigens [virulence: cytotoxin-associated antigen A (CagA); ureases; heat shock protein B; flagellin A; persistence: vacuolating cytotoxin A (VacA)]. Maternal complete blood count and liver enzymes levels were assessed at delivery by an automated analyzer. RESULTS: A significantly higher percentage of H. pylori seropositive women were found among PE cases (85.7%) compared to controls (42.9%, P < 0.001). There were no differences between pregnancies complicated by FGR without maternal hypertension (46.2%) and controls. Importantly, persistent and virulent infections (VacA/CagA seropositive patients, intermediate leukocyte blood count and aspartate aminotransferase levels) were exclusively associated with pre-eclampsia complicated by FGR, while virulent but acute infections (CagA positive/VacA negative patients, highest leukocyte blood count and aspartate aminotransferase levels) specifically correlated with PE without FGR. CONCLUSION: Our data strongly indicate that persistent and virulent H. pylori infections cause or contribute to PE complicated by FGR, but not to PE without feto-placental compromise.

Cardaropoli, Simona; Rolfo, Alessandro; Piazzese, Annalisa; Ponzetto, Antonio; Todros, Tullia

2011-01-01

135

NMR-based Molecular Rheology of Entangled Polymers in Bulk and in Nanoscopic Confinement  

NASA Astrophysics Data System (ADS)

We demonstrate the use of simple proton low-field NMR to probe the validity of the tube model of polymer dynamics. The method yields a time-domain measure of the segmental orientation autocorrelation function C(t), which in turn is directly related to the stress relaxation modulus G(t), thus providing a true molecular measure of rheologically relevant quantities. The fixed-tube model does not describe actual data well, and current work focuses on deuteron labeling schemes to investigate the relevance of contour-length fluctuation (CLF) or constraint release (CR) effects. As first results, we found that unexpectedly, CR processes are responsible for modified chain modes faster than actual reptation [1], and also that the dynamics is inhomogeneous along a given chain, stressing also the significance of CLF. We also present recent results for melt dynamics in nanoscopic confinement of long cylindrical channels of 20-400 nm diameter [2]. We consistently observe a fraction of chains whose dynamics is less isotropic on long time scales, i.e., in the Doi-Edwards regimes III (reptation) and IV (disentangled dynamics)[0pt] [1] F. Vaca Ch'avez, K. Saalw"achter, Phys. Rev. Lett. 104, 198305 (2010), [2] S. Ok et al., Macromolecules 43, 4429 (2010)

Saalwachter, Kay; Trutschel, Marie-Luise; Vaca Chavez, Fabian

2012-02-01

136

Growth Phase-Dependent Response of Helicobacter pylori to Iron Starvation  

PubMed Central

Iron is an essential nutrient that is often found in extremely limited available quantities within eukaryotic hosts. Because of this, many pathogenic bacteria have developed regulated networks of genes important for iron uptake and storage. In addition, it has been shown that many bacteria use available iron concentrations as a signal to regulate virulence gene expression. We have utilized DNA microarray technology to identify genes of the human pathogen Helicobacter pylori that are differentially regulated on a growth-inhibiting shift to iron starvation conditions. In addition, the growth phase-dependent expression of these genes was investigated by examining both exponential and stationary growth phase cultures. We identified known iron-regulated genes, as well as a number of genes whose regulation by iron concentration was not previously appreciated. Included in the list of regulated factors were the known virulence genes cagA, vacA, and napA. We examined the effect of iron starvation on the motility of H. pylori and found that exponential- and stationary-phase cultures responded differently to the stress. We further found that while growing cells are rapidly killed by iron starvation, stationary-phase cells show a remarkable ability to survive iron depletion. Finally, bioinformatic analysis of the predicted promoter regions of the differentially regulated genes led to identification of several putative Fur boxes, suggesting a direct role for Fur in iron-dependent regulation of these genes.

Merrell, D. Scott; Thompson, Lucinda J.; Kim, Charles C.; Mitchell, Hazel; Tompkins, Lucy S.; Lee, Adrian; Falkow, Stanley

2003-01-01

137

Quasispecies Development of Helicobacter pylori Observed in Paired Isolates Obtained Years Apart from the Same Host  

PubMed Central

Helicobacter pylori isolates show greater genetic diversity than other bacterial species studied, but the basis for this phenomenon is unknown. Whether detectable genomic mutation appears within an H. pylori population during persistent colonization was investigated. Paired H. pylori populations obtained across 7- to 10-year intervals from 13 patients were characterized by use of methods including polymerase chain reaction (PCR) genotyping for cagA, vacA, iceA, recA, and IS605; random arbitrarily primed DNA (RAPD)–PCR and amplified fragment length polymorphism (AFLP) analysis; and ELISA, to determine Lewis phenotypes. Genotyping, including recA sequence analysis, revealed that initial and follow-up populations represented the same population in 11 patients (85%). Nevertheless, distinct dissimilarities were shown within each of these 11 pairs by both RAPD-PCR and AFLP analyses. During follow-up, Lewis-y levels, but not Lewis-x levels, decreased significantly. The changes detected by RAPD-PCR and AFLP indicate that genetic drift occurs within H. pylori populations over the course of years of colonization of a single host.

Kuipers, Ernst J.; Israel, Dawn A.; Kusters, Johannes G.; Gerrits, Monique M.; Weel, Jan; van der Ende, Arie; van der Hulst, Rene W. M.; Wirth, Hans P.; Hook-Nikanne, Johanna; Thompson, Stuart A.; Blaser, Martin J.

2009-01-01

138

Pathogenesis of Helicobacter pylori Infection  

PubMed Central

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.

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

2006-01-01

139

Helicobacter pylori Induction of the Gastrin Promoter Through GC-Rich DNA Elements  

PubMed Central

Helicobacter pylori(H. pylori) infection has been linked to the development of chronic gastritis, duodenal ulcer disease, and gastric cancer. H. pylori- infected patients and animal models develop hypergastrinemia, chronic gastritis, and gastric atrophy. Since gastrin is an important regulator of gastric acid secretion and cell growth, H. pylori regulation of this hormone has been implicated in its pathogenesis. We investigated the effect of H. pylori infection on gastrin gene expression in mice and the effect of human isolates of the bacteria on gastrin transcription in a cell line. In addition to an increase in gastrin mRNA in H. pylori-infected mice, we found that the bacteria induced the endogenous human gastrin gene through MAP kinase-dependent signaling but not NF?B-dependent signaling. Moreover, activation of gastrin through MAPK signaling did not require CagA or VacA virulence factors. In transfection studies, we demonstrated that H. pylori-induction of the gastrin promoter thorough a GC-rich motif was mediated by inducible binding of Sp1 and Sp3 transcription factors. In conclusion, co-culturing live H. pylori bacteria with human cells is sufficient to induce gastrin gene expression.

Tucker, Tamara P.; Gray, Brian M.; Eaton, Kathyrn A.; Merchant, Juanita L.

2012-01-01

140

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

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

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

2003-07-01

141

Phase Variation in the Helicobacter pylori Phospholipase A Gene and Its Role in Acid Adaptation  

PubMed Central

Previously, we have shown that Helicobacter pylori can spontaneously and reversibly change its membrane lipid composition, producing variants with low or high content of lysophospholipids. The “lyso” variant contains a high percentage of lysophospholipids, adheres better to epithelial cells, and releases more proteins such as urease and VacA, compared to the “normal” variant, which has a low content of lysophospholipids. Prolonged growth of the normal variant at pH 3.5, but not under neutral conditions, leads to enrichment of lyso variant colonies, suggesting that the colony switch is relevant to acid adaptation. In this study we show that the change in membrane lipid composition is due to phase variation in the pldA gene. A change in the (C) tract length of this gene results in reversible frameshifts, translation of a full-length or truncated pldA, and the production of active or inactive outer membrane phospholipase A (OMPLA). The role of OMPLA in determining the colony morphology was confirmed by the construction of an OMPLA-negative mutant. Furthermore, variants with an active OMPLA were able to survive acidic conditions better than variants with the inactive form. This explains why the lyso variant is selected at low pH. Our studies demonstrate that phase variation in the pldA gene, resulting in an active form of OMPLA, is important for survival under acidic conditions. We also demonstrated the active OMPLA genotype in fresh isolates of H. pylori from patients referred to gastroscopy for dyspepsia.

Tannaes, Tone; Dekker, Niek; Bukholm, Geir; Bijlsma, Jetta J. E.; Appelmelk, Ben J.

2001-01-01

142

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

PubMed Central

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.

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

2012-01-01

143

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 Central

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.

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

2003-01-01

144

Dynamics of the Cag-type IV secretion system of Helicobacter pylori as studied by bacterial co-infections.  

PubMed

Many pathogenic Gram-negative bacteria possess type IV secretion systems (T4SS) to inject effector proteins directly into host cells to modulate cellular processes to their benefit. The human bacterial pathogen Helicobacter pylori, a major aetiological agent in the development of chronic gastritis, duodenal ulcer and gastric carcinoma, harbours the cag-T4SS to inject the cytotoxin associated Antigen (CagA) into gastric epithelial cells. This results in deregulation of major signalling cascades, actin-cytoskeletal rearrangements and eventually gastric cancer. We show here that a pre-infection with live H.?pylori has a dose-dependent negative effect on the CagA translocation efficiency of a later infecting strain. This effect of the 'first' strain was independent of any of its T4SS, the vacuolating cytotoxin (VacA) or flagella. Other bacterial pathogens, e.g. pathogenic Escherichia coli, Campylobacter jejuni, Staphylococcus aureus, or commensal bacteria, such as lactobacilli, were unable to interfere with H.?pylori's CagA translocation capacity in the same way. This interference was independent of the ?1 integrin receptor availability for H.?pylori, but certain H.?pylori outer membrane proteins, such as HopI, HopQ or AlpAB, were essential for the effect. We suggest that the specific interference mechanism induced by H.?pylori represents a cellularresponse to restrict and control CagA translocation into a host cell to control the cellular damage. PMID:23844976

Jiménez-Soto, Luisa F; Clausen, Sabine; Sprenger, Annika; Ertl, Claudia; Haas, Rainer

2013-08-08

145

High CO/sub 2/, high H/sub 2/S removal with selexol solvent  

SciTech Connect

The Selexol Solvent process of Allied Chemical Corp. for treating both sour natural gases and coal- or oil-derived synthesis gases, uses strong solubility differences of various gaseous components in Selexol that acts as physical solvent. This permits a variety of uses in any gas purification service, including bulk removal of CO/sub 2/ alone or combined with water dew point control and recovery of C/sub 5/+ paraffins, as in the Lo-Vaca Gathering Co.'s Grey Ranch gas plant; removal of small amounts of H/sub 2/S (< 1 g/100 cu ft) together with CO/sub 2/, or for higher concentrations, by using a split cycle scheme with H/sub 2/S stripping, as in Northern Natural Gas Co.'s Oates, Tex., plant; the two-stage H/sub 2/S-CO/sub 2/ absorption required in SNG or synthesis gas generation from coal to minimize air pollution by H/sub 2/S, as in Bituminous Coal Research Inc.'s Bi-Gas pilot plant; and bulk removal of H/sub 2/S together with CO/sub 2/, mercaptans, and carbonyl sulfide in a single absorber, as in Norddeutsche Erdgasaufbereitungsges. m.b.H.'s NEAG II plant.

Sweny, J.W.

1980-01-01

146

Antibacterial activities of almond skins on cagA-positive and-negative clinical isolates of Helicobacter pylori.  

PubMed

BACKGROUND: Helicobacter pylori is known to be a gastric pathogen of humans. Eradication regimens for H. pylori infection have some side effects, compliance problems, relapses, and antibiotic resistance. Therefore, the need for alternative therapies for H. pylori infections is of special interest. We have previously shown that polyphenols from almond skins are active against a range of food-borne pathogens. The aim of this study was to evaluate the antibacterial effects of natural almond skins before and after simulated human digestion and the pure flavonoid compounds epicatechin, naringenin and protocatechuic acid against H. pylori. RESULTS: H. pylori strains were isolated from gastric biopsy samples following standard microbiology procedures. Also, cagA and vacA genes were identified using PCR. Susceptibility studies on 34 strains of H. pylori, including two reference strains (ATCC 43504, ATCC 49503), were performed by the standard agar dilution method.Natural almond skin was the most effective compound against H. pylori (MIC range, 64 to 128 mug/ml), followed by natural skin post gastric digestion (MIC range, 128 to 512 mug/ml), and natural almond skin post gastric plus duodenal digestion (MIC range, 256 to 512 mug/ml). Amongst the pure flavonoid compounds, protocatechuic acid showed the greatest activity (MIC range, 128 to 512 mug/ml) against H. pylori strains. CONCLUSIONS: The Polyphenols from almond skins were effective in vitro against H. pylori, irrespective of genotype status and could therefore be used in combination with antibiotics as a novel strategy for antibiotic resistance. PMID:23659287

Bisignano, Carlo; Filocamo, Angela; La Camera, Erminia; Zummo, Sebastiana; Fera, Maria Teresa; Mandalari, Giuseppina

2013-05-01

147

Helicobacter pylori-induced loss of survivin and gastric cell viability is attributable to secreted bacterial gamma-glutamyl transpeptidase activity.  

PubMed

Helicobacter pylori is the etiologic agent of a series of gastric pathologies that may culminate in the development of gastric adenocarcinoma. An initial step in this process is the loss of glandular structures in the gastric mucosa, presumably as the consequence of increased apoptosis and reduced cellular regeneration, which may be attributed to the combination of several bacterial and host factors and to an unfavorable proinflammatory environment. In a previous study, we showed that survivin, a member of the inhibitor of apoptosis protein family, is expressed in the normal human gastric mucosa and that its levels decrease in the mucosa of infected patients and in gastric cells exposed in culture to the bacteria, coincident with increased cell death in the latter case. We investigated the bacterial factors responsible for loss of survivin in gastric cells exposed to H. pylori. The results of this study indicated that the loss of survivin due to H. pylori infection involves proteasome-mediated degradation of the protein. Studies with isogenic mutants deficient in either CagA, VacA, lipopolysaccharide, or gamma-glutamyl transpeptidase (GGT) implicated the latter in H. pylori-induced loss of survivin and cell viability. Moreover, experiments with the GGT inhibitor 6-diazo-5-oxo-l-norleucine and purified recombinant GGT protein indicated that secreted bacterial GGT activity was required and sufficient to induce these effects. PMID:23847060

Valenzuela, Manuel; Bravo, Denisse; Canales, Jimena; Sanhueza, Carlos; Díaz, Natalia; Almarza, Oscar; Toledo, Héctor; Quest, Andrew F G

2013-07-11

148

Gastric secretion and ulcer healing in mouse stomach infected with cytotoxin expressing strain of Helicobacter pylori.  

PubMed

Helicobacter pylori (Hp) is a major risk factor of peptic ulcer but studies on the relation between Hp infection and gastric pathology are limited due to lack of convenient models resembling Hp infection in humans. We studied the effects of inoculation of conventional BALB/c mice with toxigenic type I Hp (cagA+ and vacA+) and non-toxigenic type II Hp (cagA- and vacA-) vs administration of vehicle on gastric secretion and healing of gastric ulcers. The gastric secretion studies were performed on mice with chronic gastric fistula before and after inoculation with toxigenic or non-toxigenic Hp strain or administration of vehicle (saline). Gastric ulcers were produced in mice inoculated with toxigenic and non-toxigenic Hp strain or vehicle and then sacrificed at day 0 and after 2, 4, 7, 14 and 28 days. Ulcer area and gastric blood flow (GBF), plasma gastrin and gastric luminal somatostatin were determined. Gastric mucosal biopsy specimens were also taken for the assessment of the presence of viable Hp using rapid urease test, the Hp-culture and the reverse transcriptase--polymerase chain reaction (RT-PCR) analysis of the signal for Hp CagA. Gastric acid output was reduced by over 50% immediately after Hp inoculation and this effect persisted during all time intervals tested, being significantly more pronounced in type I Hp-infected stomach. The area (7 mm2) of ulcers in control mice decreased gradually and then continued to decline during 14 days to disappear almost completely after 28 days. In contrast, the ulcers were present till day 28 in all mice infected with type I or type II Hp strain being significantly larger especially with type I Hp-infection. The GBF in control mice showed gradual rise with decreasing ulcer size being significantly higher at the ulcer margin than the ulcer crater and reached after 14 and 28 days the value not significantly different from that in vehicle-administered mice. In contrast, the GBF in type I Hp-infected mice but to a lesser extent, in type II Hp infected mice was significantly lower than in the vehicle controls, both at the ulcer margin and the crater of ulcers at all tested days. Hp-infection was accompanied by significant increment in plasma gastrin and the fall in gastric somatostatin contents observed at all test days, particularly in mice infected with type I Hp strain. Edema of surface epithelium appeared after 7 days and wak but significant mucosal inflammatory infiltration occurred after 14 days to further increase after 28 days, especially in type I Hp and less in type II Hp infected mice. We conclude that conventional mice with gastric ulcers can be successfully infected by both toxigenic and non-toxigenic Hp strains and this infection markedly reduces gastric acid secretion and delays healing of ulcers probably due to the fall in mucosal microcirculation in ulcer area, mucosal inflammation and impairment in gastric-somatostatin link. PMID:9789792

Brzozowski, T; Konturek, P C; Konturek, S J; Karczewska, E; Pajdo, R; Stachura, J; Ghiara, P; Hahn, E G

1998-09-01

149

The immunogenetics and pathogenesis of gastric cancer. Highlights of the First Sino-European Workshop on the Immunogenetics and Pathogenesis of Gastric Cancer.  

PubMed

Clinical scientists from eight European countries and China gathered in the ancient Chinese capital of Xi'an on April 26-28, 2001 to discuss collaboration on a modern approach to gastric cancer prevention. Participants at the First Sino-European Workshop on Immunogenetics and Pathogenesis of Gastric Cancer presented their most up-to-date research results on topics ranging from epidemiology and immune mechanisms to Helicobacter pylori and vaccine development. Researchers then formed groups with their Chinese or European counterparts to plan future research endeavors which will benefit Chinese and European populations alike. After 3 years of organization between the Institute of Digestive Diseases of the Fourth Medical University in Xi'an, China and the Laboratory of Immunogenetics, VU University Medical Center in Amsterdam, the first workshop came into being under the joint sponsorship of the Commission of the European Union, National Natural Science Foundation of China and the Institute of Digestive Diseases, Xi'an, China. As gastric cancer is the most prevalent malignant tumor in China, the workshop was of special significance to the Chinese researchers and to the Chinese population in general. During the workshop, presentations on the epidemiology of gastric cancer showed that this disease is in fact common the world over: it is the second most common cancer next to lung cancer and about 1 million new cases were diagnosed in 2000. Three-quarters of the cases of gastric cancer occur in Asia, and approximately 80% of these cases are in China and Japan. Genetic factors and environmental factors such as diet and H. pylori infection play a role in gastric carcinogenesis. As a recognized cause of gastric cancer, H. pylori was the subject of various presentations ranging from immunological studies, molecular analysis of strains and pathogenesis to vaccine development. Specific areas of discussion included bacterial-epithelial interactions in H. pylori infection, epidemiology in China, global distribution of vacA and cagA genotypes, new evidence for host factors, nonsteroidal antiinflammatory drugs and H. pylori as independent risk factor for gastric cancer, new diagnostic techniques for H. pylori using serum levels of pepsinogen I, and autoimmune processes in corpus atrophy. Vaccine development using a variety of strategies against H. pylori was the subject of an entire session of talks. Oral immunization with urease with Escherichia coli heat labile enterotoxin was shown to be safe and immunogenic in humans as a mucosal adjuvant. Results of a study using attenuated Salmonella typhimurium as a vehicle for DNA-mediated immunization in mice were also presented. A final presentation discussed an ongoing trial comparing strain variability in the vacA and cagA gene sequences and disease expression between H. pylori infection in Europe and China. Researchers also discussed the role of IL1 gene family and TNF gene polymorphisms in gastric pathology and various immune mechanisms involved in gastric cancer, such as down-regulation of NF kappa B, IL-1 and IL-1RA, cyclooxygenase signalling, and identification of MGAg antibodies. An interactive discussion followed each presentation and ideas and suggestions were provided. According to specialty, the presenters were then assigned to groups of four or five to make plans for joint research projects. A number of international and Chinese observers were present, including representatives from the European Commission, the World Health Organization and the Chinese National Center for Biotechnology Development, and offered input on the financial feasibility of such projects. PMID:12532177

Wu, K; Crusius, J B A; Fan, D; Peña, A S

2002-06-01

150

Finding the smoking gun: protein tyrosine phosphatases as tools and targets of unicellular microorganisms and viruses.  

PubMed

Protein tyrosine phosphatases (PTPs) are increasingly recognized as important effectors of host-pathogen interactions. Since Guan and Dixon reported in 1990 that phosphatase YopH serves as an essential virulence determinant of Yersinia, the field shifted significantly forward, and dozens of PTPs were identified in various microorganisms and even in viruses. The discovery of extensive tyrosine signaling networks in non-metazoan organisms refuted the moth-eaten paradigm claiming that these organisms rely exclusively on phosphoserine/phosphothreonine signaling. Similarly to humans, phosphotyrosine signaling is thought to comprise a small fraction of total protein phosphorylation, but plays a disproportionately important role in cell-cycle control, differentiation, and invasiveness. Here we summarize the state-of-art knowledge on PTPs of important non-metazoan pathogens (Listeria monocytogenes, Staphylococcus aureus, Porphyromonas gingivalis, Caulobacter crescentus, Yersinia, Synechocystis, Leishmania, Plasmodium falciparum, Entamoeba histolytica, etc.), and focus also at the microbial proteins affecting directly or indirectly the PTPs of the host (Mycobacterium tuberculosis MTSA-10, Bacillus anthracis anthrax toxin, streptococcal ? protein, Helicobacter pylori CagA and VacA, Leishmania GP63 and EF-1?, Plasmodium hemozoin, etc.). This is the first review summarizing the knowledge on biological activity and pharmacological inhibition of non-metazoan PTPs, with the emphasis of those important in host-pathogen interactions. Targeting of numerous non-metazoan PTPs is simplified by the fact that they act either as ectophosphatases or are secreted outside of the pathogen. Interfering with tyrosine phosphorylation represents a powerful pharmacologic approach, and even though the PTP inhibitors are difficult to develop, lifting the fog of phosphatase inhibition is of the great market potential and further clinical impact. PMID:22360485

Heneberg, P

2012-01-01

151

From array-based hybridization of Helicobacter pylori isolates to the complete genome sequence of an isolate associated with MALT lymphoma  

PubMed Central

Background elicobacter pylori infection is associated with several gastro-duodenal inflammatory diseases of various levels of severity. To determine whether certain combinations of genetic markers can be used to predict the clinical source of the infection, we analyzed well documented and geographically homogenous clinical isolates using a comparative genomics approach. Results A set of 254 H. pylori genes was used to perform array-based comparative genomic hybridization among 120 French H. pylori strains associated with chronic gastritis (n = 33), duodenal ulcers (n = 27), intestinal metaplasia (n = 17) or gastric extra-nodal marginal zone B-cell MALT lymphoma (n = 43). Hierarchical cluster analyses of the DNA hybridization values allowed us to identify a homogeneous subpopulation of strains that clustered exclusively with cagPAI minus MALT lymphoma isolates. The genome sequence of B38, a representative of this MALT lymphoma strain-cluster, was completed, fully annotated, and compared with the six previously released H. pylori genomes (i.e. J99, 26695, HPAG1, P12, G27 and Shi470). B38 has the smallest H. pylori genome described thus far (1,576,758 base pairs containing 1,528 CDSs); it contains the vacAs2m2 allele and lacks the genes encoding the major virulence factors (absence of cagPAI, babB, babC, sabB, and homB). Comparative genomics led to the identification of very few sequences that are unique to the B38 strain (9 intact CDSs and 7 pseudogenes). Pair-wise genomic synteny comparisons between B38 and the 6 H. pylori sequenced genomes revealed an almost complete co-linearity, never seen before between the genomes of strain Shi470 (a Peruvian isolate) and B38. Conclusion These isolates are deprived of the main H. pylori virulence factors characterized previously, but are nonetheless associated with gastric neoplasia.

2010-01-01

152

Comparison of Helicobacter pylori virulence gene expression in vitro and in the Rhesus macaque.  

PubMed

We used a quantitative real-time reverse transcriptase PCR assay to measure the transcript abundance of 46 known and putative Helicobacter pylori virulence genes, including 24 genes on the Cag pathogenicity island. The expression profile of H. pylori cells grown in vitro was also compared to expression in vivo after experimental infection of rhesus macaques. Transcript abundance in vitro (mid-log phase) ranged from about 0.004 (feoB and hpaA) to 20 (ureAB, napA, and cag25) copies/cell. Expression of most genes was repressed during the transition from logarithmic- to stationary-phase growth, but several well-characterized H. pylori virulence genes (katA, napA, vacA, and cagA) were induced. Comparison of results in the rhesus macaque with similar data from humans showed a strong correlation (r = 0.89). The relative in vivo expression in the rhesus monkey was highly correlated with in vitro expression during mid-log (r = 0.89)- and stationary (r = 0.88)-phase growth. Transcript abundance was on average three- to fourfold reduced in vivo compared to in vitro during mid-log phase. However, when compared to stationary phase, increased expression in vivo was observed for 6 of 7 genes on a contiguous portion of the pathogenicity island, several of which are thought to encode the H. pylori type IV structural pilus and its accessory proteins. These results suggest the possibility that some genes encoding the H. pylori type IV structural pilus and accessory proteins may form an operon that is induced during growth in vivo. PMID:16041003

Boonjakuakul, Jenni K; Canfield, Don R; Solnick, Jay V

2005-08-01

153

Ubiquitin-proteasome-rich cytoplasmic structures in neutrophils of patients with Shwachman-Diamond syndrome  

PubMed Central

Background Shwachman–Diamond syndrome is an autosomal recessive disorder in which severe bone marrow dysfunction causes neutropenia and an increased risk of leukemia. Recently, novel particulate cytoplasmic structures, rich in ubiquitinated and proteasomal proteins, have been detected in epithelial cells and neutrophils from patients with Helicobacter pylori gastritis and several epithelial neoplasms. Design and Methods Blood neutrophils from 13 cases of Shwachman–Diamond syndrome – ten with and three without SBDS gene mutation – and ten controls were investigated by confocal microscopy and ultrastructural immunocytochemistry using antibodies against ubiquitinated proteins, proteasomes, p62 protein, and Helicobacter pylori VacA, urease and outer membrane proteins. Results Many extensively disseminated particulate cytoplasmic structures, accounting for 22.78±5.57% (mean ± standard deviation) of the total cytoplasm, were found in blood neutrophils from mutated Shwachman–Diamond syndrome patients. The particulate cytoplasmic structures showed immunoreactivity for polyubiquitinated proteins and proteasomes, but no reactivity for Helicobacter pylori products, which are present in particulate cytoplasmic structures of Helicobacter pylori-positive gastritis. Neutrophils from patients with Shwachman–Diamond syndrome frequently showed p62-positive autophagic vacuoles and apoptotic changes in 5% of cells. No particulate cytoplasmic structures were observed in most control neutrophils; however, in a few cells from two cases we noted focal development of minute particulate cytoplasmic structures, accounting for 0.74±0.56% of the total cytoplasm (P<0.001 versus particulate cytoplasmic structures from mutated Shwachman–Diamond syndrome patients). Neutrophils from non-mutated Shwachman–Diamond-syndrome-like patients resembled controls in two cases, and a third case showed particulate cytoplasmic structure patterns intermediate between those in controls and those in mutated Shwachman–Diamond syndrome patients. Conclusions Particulate cytoplasmic structures are a prominent feature of neutrophils from patients with Shwachman–Diamond syndrome. They may help us to understand the mechanism of granulocyte dysfunction and the neoplastic risk of the disease.

Necchi, Vittorio; Minelli, Antonella; Sommi, Patrizia; Vitali, Agostina; Caruso, Roberta; Longoni, Daniela; Frau, Maria Rita; Nasi, Cristina; De Gregorio, Fabiola; Zecca, Marco; Ricci, Vittorio; Danesino, Cesare; Solcia, Enrico

2012-01-01

154

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

PubMed Central

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.

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

155

Phylogeographic Origin of Helicobacter pylori Is a Determinant of Gastric Cancer Risk  

PubMed Central

Background and Aims Helicobacter pylori colonises the stomach in half of all humans, and is the principal cause of gastric cancer, the second leading cause of cancer death worldwide. While gastric cancer rates correlate with H. pylori prevalence in some areas, there are regions where infection is nearly universal, but rates of gastric cancer are low. In the case of Colombia, there is a 25-fold increase in gastric cancer rate in the Andean mountain (high risk) region compared to the coastal (low risk) region, despite similarly high (~90%) H. pylori prevalence in the two locations. Our aim was to investigate the ancestral origin of H. pylori strains isolated from subjects in these high and low risk regions and to determine whether this is a predictive determinant of precancerous lesions. Methods Multi-locus sequence typing was used to investigate phylogeographic origins of infecting H. pylori strains isolated from subjects in the Pacific coast and Andean mountains in the state of Nariño, Colombia. We analysed 64 subjects infected with cagA+ vacA s1m1 strains. Gastric biopsy slides from each individual were scored for histologic lesions and evaluated for DNA damage by immunohistochemistry. Results We show that strains from the high risk region were all of European phylogeographic origin, whereas those from the low risk region were of either European (34%) or African origin (66%). European strain origin was strongly predictive of increased premalignant histologic lesions and epithelial DNA damage, even in the low risk region; African strain origin was associated with reduced severity of these parameters. Conclusion The phylogeographic origin of H. pylori strains provides an explanation for geographic differences in cancer risk deriving from this infection.

de Sablet, Thibaut; Piazuelo, M. Blanca; Shaffer, Carrie L.; Schneider, Barbara G.; Asim, Mohammad; Chaturvedi, Rupesh; Bravo, Luis E.; Sicinschi, Liviu A.; Delgado, Alberto G.; Mera, Robertino M.; Israel, Dawn A.; Romero-Gallo, Judith; Peek, Richard M.; Cover, Timothy L.; Correa, Pelayo; Wilson, Keith T.

2011-01-01

156

Cell vacuolation caused by Vibrio cholerae hemolysin.  

PubMed

Non-O1 strains of Vibrio cholerae implicated in gastroenteritis and diarrhea generally lack virulence determinants such as cholera toxin that are characteristic of epidemic strains; the factors that contribute to their virulence are not understood. Here we report that at least one-third of diarrhea-associated nonepidemic V. cholerae strains from Mexico cause vacuolation of cultured Vero cells. Detailed analyses indicated that this vacuolation was related to that caused by aerolysin, a pore-forming toxin of Aeromonas; it involved primarily the endoplasmic reticulum at early times (approximately 1 to 4 h after exposure), and resulted in formation of large, acidic, endosome-like multivesicular vacuoles (probably autophagosomes) only at late times (approximately 16 h). In contrast to vacuolation caused by Helicobacter pylori VacA protein, that induced by V. cholerae was exacerbated by agents that block vacuolar proton pumping but not by endosome-targeted weak bases. It caused centripetal redistribution of endosomes, reflecting cytoplasmic alkalinization. The gene for V. cholerae vacuolating activity was cloned and was found to correspond to hlyA, the structural gene for hemolysin. HlyA protein is a pore-forming toxin that causes ion leakage and, ultimately, eukaryotic cell lysis. Thus, a distinct form of cell vacuolation precedes cytolysis at low doses of hemolysin. We propose that this vacuolation, in itself, contributes to the virulence of V. cholerae strains, perhaps by perturbing intracellular membrane trafficking or ion exchange in target cells and thereby affecting local intestinal inflammatory or other defense responses. PMID:11179335

Figueroa-Arredondo, P; Heuser, J E; Akopyants, N S; Morisaki, J H; Giono-Cerezo, S; Enríquez-Rincón, F; Berg, D E

2001-03-01

157

Molecular epidemiology, population genetics, and pathogenic role of Helicobacter pylori  

PubMed Central

Helicobacter pylori infection is linked to various gastroduodenal diseases; however, only approximately 20% of infected individuals develop severe diseases. Despite the high prevalence of H. pylori infection in Africa and South Asia, the incidence of gastric cancer in these areas is much lower than in other countries. Furthermore, the incidence of gastric cancer tends to decrease from north to south in East Asia. Such geographic differences in the pathology can be explained, at least in part, by the presence of different types of H. pylori virulence factors, especially cagA, vacA, and the right end of the cag pathogenicity island. The genotype of the virulence genes is also useful as a tool to track human migration utilizing the high genetic diversity and frequent recombination between different H. pylori strains. Multilocus sequence typing (MLST) analysis using 7 housekeeping genes can also help predict the history of human migrations. Population structure analysis based on MLST has revealed 7 modern population types of H. pylori, which derived from 6 ancestral populations. Interestingly, the incidence of gastric cancer is closely related to the distribution of H. pylori populations. The different incidence of gastric cancer can be partly attributed to the different genotypes of H. pylori circulating in different geographic areas. Although approaches by MLST and virulence factors are effective, these methods focus on a small number of genes and may miss information conveyed by the rest of the genome. Genome-wide analyses using DNA microarray or whole-genome sequencing technology give a broad view on the genome of H. pylori. In particular, next-generation sequencers, which can read DNA sequences in less time and at lower costs than Sanger sequencing, enabled us to efficiently investigate not only the evolution of H. pylori, but also novel virulence factors and genomic changes related to drug resistance.

Suzuki, Rumiko; Shiota, Seiji; Yamaoka, Yoshio

2012-01-01

158

Comparison of Helicobacter pylori Virulence Gene Expression In Vitro and in the Rhesus Macaque  

PubMed Central

We used a quantitative real-time reverse transcriptase PCR assay to measure the transcript abundance of 46 known and putative Helicobacter pylori virulence genes, including 24 genes on the Cag pathogenicity island. The expression profile of H. pylori cells grown in vitro was also compared to expression in vivo after experimental infection of rhesus macaques. Transcript abundance in vitro (mid-log phase) ranged from about 0.004 (feoB and hpaA) to 20 (ureAB, napA, and cag25) copies/cell. Expression of most genes was repressed during the transition from logarithmic- to stationary-phase growth, but several well-characterized H. pylori virulence genes (katA, napA, vacA, and cagA) were induced. Comparison of results in the rhesus macaque with similar data from humans showed a strong correlation (r = 0.89). The relative in vivo expression in the rhesus monkey was highly correlated with in vitro expression during mid-log (r = 0.89)- and stationary (r = 0.88)-phase growth. Transcript abundance was on average three- to fourfold reduced in vivo compared to in vitro during mid-log phase. However, when compared to stationary phase, increased expression in vivo was observed for 6 of 7 genes on a contiguous portion of the pathogenicity island, several of which are thought to encode the H. pylori type IV structural pilus and its accessory proteins. These results suggest the possibility that some genes encoding the H. pylori type IV structural pilus and accessory proteins may form an operon that is induced during growth in vivo.

Boonjakuakul, Jenni K.; Canfield, Don R.; Solnick, Jay V.

2005-01-01

159

The Oxysterol-binding Protein Homologue ORP1L Interacts with Rab7 and Alters Functional Properties of Late Endocytic Compartments  

PubMed Central

ORP1L is a member of the human oxysterol-binding protein (OSBP) family. ORP1L localizes to late endosomes (LEs)/lysosomes, colocalizing with the GTPases Rab7 and Rab9 and lysosome-associated membrane protein-1. We demonstrate that ORP1L interacts physically with Rab7, preferentially with its GTP-bound form, and provide evidence that ORP1L stabilizes GTP-bound Rab7 on LEs/lysosomes. The Rab7-binding determinant is mapped to the ankyrin repeat (ANK) region of ORP1L. The pleckstrin homology domain (PHD) of ORP1L binds phosphoinositides with low affinity and specificity. ORP1L ANK- and ANK+PHD fragments induce perinuclear clustering of LE/lysosomes. This is dependent on an intact microtubule network and a functional dynein/dynactin motor complex. The dominant inhibitory Rab7 mutant T22N reverses the LE clustering, suggesting that the effect is dependent on active Rab7. Transport of fluorescent dextran to LEs is inhibited by overexpression of ORP1L. Overexpression of ORP1L, and in particular the N-terminal fragments of ORP1L, inhibits vacuolation of LE caused by Helicobacter pylori toxin VacA, a process also involving Rab7. The present study demonstrates that ORP1L binds to Rab7, modifies its functional cycle, and can interfere with LE/lysosome organization and endocytic membrane trafficking. This is the first report of a direct connection between the OSBP-related protein family and the Rab GTPases.

Johansson, Marie; Lehto, Markku; Tanhuanpaa, Kimmo; Cover, Timothy L.; Olkkonen, Vesa M.

2005-01-01

160

Association between Helicobacter pylori Virulence Factors and Gastroduodenal Diseases in Okinawa, Japan  

PubMed Central

The incidence of gastric cancer in Okinawa is lowest in Japan. Some previous reports using small number of strains suggested that the high prevalence of Helicobacter pylori with Western-type cagA in Okinawa compared to other areas in Japan might contribute to the low incidence of gastric cancer. It has still not been confirmed why the prevalence of Western-type cagA strains is high in Okinawa. We examined the association between the virulence factors of H. pylori and gastroduodenal diseases in Okinawa. The genotypes of cagA and vacA of 337 H. pylori strains were determined by PCR and gene sequencing. The genealogy of these Western-type cagA strains in Okinawa was analyzed by multilocus sequence typing (MLST). Overall, 86.4% of the strains possessed cagA: 70.3% were East-Asian type and 16.0% were Western type. After adjustment by age and sex, the presence of East-Asian-type cagA/vacA s1m1 genotypes was significantly associated with gastric cancer compared to gastritis (odds ratio = 6.68, 95% confidence interval = 1.73 to 25.8). The structure of Western-type CagA in Okinawa was different from that of typical Western-type CagA found in Western countries. Intriguingly, MLST analysis revealed that the majority of Western-type cagA strains formed individual clusters but not hpEurope. Overall, low prevalence of gastric cancer in Okinawa may result from the high prevalence of non-East-Asian-type cagA strains. The origin of Western-type cagA strains in Okinawa may be different from those of Western countries.

Matsunari, Osamu; Shiota, Seiji; Suzuki, Rumiko; Watada, Masahide; Kinjo, Nagisa; Murakami, Kazunari; Fujioka, Toshio; Kinjo, Fukunori

2012-01-01

161

Mesosiderites: A Chronologic and Petrologic Synthesis  

NASA Astrophysics Data System (ADS)

Recent petrologic, chemical, and isotopic analyses of mesosiderite clasts and whole rocks allow construction of the evolutionary history of the mesosiderite parent body (MPB) as shown in the figure. I. Initial Melting ~4.56 Ga Ago. Numerous chronologic measurements indicate that initial melting of the MPB occurred shortly after accretion, at about the same time that the eucrites and angrites formed. For example, a zircon grain from a basaltic clast in Vaca Muerta yielded a Pb-Pb age of 4.563 Ga (Ireland and Wlotzka, 1992). The 4.56-Ga event on the MPB is probably responsible for forming the monogenic basaltic clasts that compositionally resemble typical eucrites (Rubin and Mittlefehldt, 1992). II. Crustal Remelting ~4.47 Ga Ago. Internal Sm-Nd isochron ages of 4.47 Ga have been determined for gabbroic pebble 12 from Vaca Muerta and a basaltic clast from Mt. Padbury (Stewart et al., 1991). Pebble 12 is one of many clasts in mesosiderites that are highly depleted in incompatible elements and probably represent remelted crustal rocks (Rubin and Mittlefehldt, 1992). Because variation of Fe/Mn with Fe/Mg in pyroxenes from these clasts follows a trend defined by FeO reduction from a melt (Mittlefehldt, 1990), and because the reducing agents (e.g., P) were likely to have been introduced during metal-silicate mixing, the age of pebble 12 indicates that metal-silicate mixing had to have occurred >=4.47 Ga ago. III. Localized Impact Melting 4.5-3.9 Ga Ago. Localized impact melting and metamorphism were widespread on the eucrite parent body as indicated by many ages that were partially or totally reset <4.56 Ga ago. Impact melt material is common in mesosiderites of all petrologic types, and ages between 4.5-3.9 Ga are preserved. Quench-textured pebble 5 from Vaca Muerta, which is likely to have formed from a localized impact melt of material resembling a cumulate eucrite (Rubin and Jerde, 1987), has an internal isochron age of 4.42 Ga (Stewart et al., 1992). The high temperature of these localized events places them before the 3.9-Ga event (below); however, because no extensive crustal remelting is evident, the metamorphism must have occurred after 4.47 Ga ago. The mesosiderite breccias were assembled during this phase of MPB history. IV. Collisional Disruption and Reassembly ~3.9 Ga Ago. Mesosiderites were degassed by a major thermal event ~3.9 Ga ago that heated the rocks to ~500 degrees C; this event may mark collisional disruption and gravitational reassembly of the MPB (Bogard et al., 1990). The surface breccias were deeply buried at this time and heated somewhat above the Fe-Ni solvus, resetting the metallographic cooling rates to ~1 degree C/Ma. This event may also account for some of the reported disturbances in the Rb- Sr, Sm-Nd, and Pb-Pb ages of a few mesosiderites. V. Impact Excavation and Ejection <<3.9 Ga Ago. Mesosiderites have cosmic ray exposure ages ranging from ~10-150 Ma, which represent the epoch when individual mesosiderites were excavated from the MPB or from a >=10-m-size MPB fragment. References: Bogard D.D., Garrison D.H., Jordan J.L. and Mittlefehldt D. (1990) Geochim. Cosmochim. Acta 54, 2549-2564. Ireland T.R. and Wlotzka F. (1992) Earth Planet. Sci. Lett. 109, 1-10. Mittlefehldt D.W. (1990) Geochim. Cosmochim. Acta 54, 1165-1173. Rubin A.E. and Jerde E.A. (1987) Earth Planet. Sci. Lett. 84, 1-14. Rubin A.E. and Mittlefehldt D.W. (1992) Geochim. Cosmochim. Acta 56, 827-840. Stewart B.W., Cheng Q.C., Papanastassiou D.A. and Wasserburg G.J. (1991) Lunar Planet. Sci. (abstract) 22, 1333. Stewart B.W., Papanastassiou D.A. and Wasserburg G.J. (1992) Lunar Planet. Sci. (abstract) 23, 1365.

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

1992-07-01

162

VIII Olimpíada Brasileira de Astronomia e Astronáutica  

NASA Astrophysics Data System (ADS)

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.

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

163

Pneumatocele selar a tensi?n: Reporte de un caso y revisi?n de la literatura  

PubMed Central

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.

Campero, Alvaro; Ajler, Pablo; Goldschmidt, Ezequiel; Bendersky, Damian; Campero, Abraham

2012-01-01

164

Induction of cyclooxygenase-2 overexpression in human gastric epithelial cells by Helicobacter pylori involves TLR2/TLR9 and c-Src-dependent nuclear factor-kappaB activation.  

PubMed

Gastric epithelial cells were incubated with a panel of clinical isolates of Helicobacter pylori, including nonulcer dyspepsia with gastritis (HS, n = 20), gastric ulcer (HU, n = 20), duodenal ulcer (HD, n = 21), and gastric cancer (HC, n = 20). HC strains induced a higher cyclooxygenase-2 (COX-2) expression than those from HS, HD, and HU. The bacterial virulence factors and the host cellular pathways were investigated. Virulence genes of iceA, vacA, babA2, cagA 3' repeat region, and hrgA failed to show any association with the disease status and COX-2 expression. Methylation-specific polymerase chain reaction revealed HC strains not affecting the methylation status of COX-2 promoter. Nuclear factor (NF)-kappaB, NF-interleukin 6, and cAMP response element were found to be involved in COX-2 induction. We explored a novel NF-kappaB activation pathway. The mutants of TLR2 and TLR9, but not TLR4, inhibited H. pylori-induced COX-2 promoter activity, and neutralizing antibodies for TLR2 and TLR9 abolished H. pylori-induced COX-2 expression. Phosphatidylinositol-specific phospholipase C (PI-PLC), protein kinase C (PKC), and Src inhibitors inhibited COX-2 induction. The dominant-negative mutants of NIK and various IkappaB kinase complexes, including IKKbeta (Y188F), IKKbeta (Y199F), and IKKbeta (FF), inhibited the COX-2 promoter activity. Phosphorylation of GST-IKKbeta (132-206) at Tyr188 and Tyr199 by c-Src was found after H. pylori infection. In summary, H. pylori induces COX-2 expression via activations of NF-kappaB, NF-interleukin 6, the cAMP response element. In NF-kappaB activation, H. pylori acts through TLR2/TLR9 to activate both the cascade of PI-PLCgamma/PKCalpha/c-Src/IKKalpha/beta and the cascade of NIK/IKKalpha/beta, resulting in the IkappaBalpha degradation and the expression of COX-2 gene. The COX-2 overexpression may contribute to the carcinogenesis in patients colonized with these strains. PMID:15456896

Chang, Ya Jen; Wu, Ming Shiang; Lin, Jaw Town; Sheu, Bor Shyang; Muta, Tatsushi; Inoue, Hiroyasu; Chen, Ching-Chow

2004-09-29

165

In vitro effect of amoxicillin and clarithromycin on the 3' region of cagA gene in Helicobacter pylori isolates  

PubMed Central

AIM: To evaluate the in vitro effect of amoxicillin and clarithromycin on the cag pathogenicity island (cag PAI). METHODS: One hundred and forty-nine clinical isolates of Helicobacter pylori (H. pylori) cultured from gastric biopsies from 206 Colombian patients with dyspeptic symptoms from a high-risk area for gastric cancer were included as study material. Antimicrobial susceptibility was determined by the agar dilution method. Resistant isolates at baseline and in amoxicillin and clarithromycin serial dilutions were subjected to genotyping (cagA, vacA alleles s and m), Glu-Pro-Ile-Tyr-Ala (EPIYA) polymerase chain reaction and random amplified polymorphic DNA (RAPD). Images of the RAPD amplicons were analyzed by Gel-Pro Analyzer 4.5 program. Cluster analyses was done using SPSS 15.0 statistical package, where each of the fingerprint bands were denoted as variables. Dendrograms were designed by following Ward’s clustering method and the estimation of distances between each pair of H. pylori isolates was calculated with the squared Euclidean distance. RESULTS: Resistance rates were 4% for amoxicillin and 2.7% for clarithromycin with 2% double resistances. Genotyping evidenced a high prevalence of the genotype cagA-positive/vacA s1m1. The 3’ region of cagA gene was successfully amplified in 92.3% (12/13) of the baseline resistant isolates and in 60% (36/60) of the resistant isolates growing in antibiotic dilutions. Upon observing the distribution of the number of EPIYA repetitions in each dilution with respect to baseline isolates, it was found that in 61.5% (8/13) of the baseline isolates, a change in the number of EPIYA repetitions lowered antibiotic pressure. The gain and loss of EPIYA motifs resulted in a diversity of H. pylori subclones after bacterial adjustment to changing conditions product of antibiotic pressure. RAPD PCR evidenced the close clonal relationship between baseline isolates and isolates growing in antibiotic dilutions. CONCLUSION: Antibiotic pressure does not induce loss of the cag pathogenicity island, but it can lead - in most cases - to genetic rearrangements within the 3’ region cagA of the founding bacteria that can affect the level of tyrosine phosphorylation impacting on its cellular effects and lead to divergence of cagA-positive subclones.

Bustamante-Rengifo, Javier Andres; Matta, Andres Januer; Pazos, Alvaro; Bravo, Luis Eduardo

2013-01-01

166

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

SciTech Connect

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.

Not Available

1994-08-01

167

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)

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).

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

2013-04-01

168

Moléculas orgánicas obtenidas en simulaciones experimentales del medio interestelar.  

NASA Astrophysics Data System (ADS)

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.

Muñoz-Caro, Guillermo Manuel

169

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

USGS Publications Warehouse

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

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

1960-01-01

170

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

NASA Astrophysics Data System (ADS)

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.

Misstear, Bruce D. R.; Beeson, Sarah

171

The conceptualization model problem—surprise  

NASA Astrophysics Data System (ADS)

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.

Bredehoeft, John

2005-03-01