Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.1.5 (urease)
7,257 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Low dose E. coli heat-labile enterotoxin (LT), delivered orally or enterically, has been used as an adjuvant for Helicobacter pylori (H. pylori) urease in healthy adults. In this study we aim to test the safety and adjuvant efficacy of LT delivered rectally together with recombinant H. pylori urease. Eighteen healthy adults without present or past H. pylori infection were enrolled in a double blind, randomized, ascending dose study to receive either urease (60 mg), or urease (60 mg) + LT (5 or 25 microg). The immunization preparation was administered per rectum on days 0, 14 and 28. Serum, stool and saliva anti-urease and anti-LT IgG and IgA antibodies (Abs) were measured and urease-specific and LT-specific antigen secreting cells (ASCs) were counted in peripheral blood at baseline and 7 (ASC counts) or 14 days (antibody levels) after each dosing. Peripheral blood lymphoproliferation assays were also performed at baseline and at the end of the study. Rectally delivered urease and LT were well tolerated. Among the 12 subjects assigned to urease+LT, 2 (16.7%) developed anti-urease IgG Abs, 1 (8.3%) developed anti-urease IgA Abs, and 3 (25%) showed urease-specific IgA(+) ASCs. Immune responses to LT were more vigorous, especially in subjects exposed to 5 microg LT. In the urease+ 5 microg LT group, anti-LT IgG and IgA Abs developed in 60 and 80% of the subjects, respectively, while LT-specific IgG(+) and IgA(+) ASCs were detected in all subjects. The magnitude of the anti-LT response was much higher than the response to urease. No IgA anti-urease or anti-LT Abs were detected in stool or saliva and lymphocyte proliferative responses to urease were unsatisfactory. In conclusion, rectal delivery of 5 microg LT is safe and induces vigorous systemic anti-LT immune responses. Further studies are needed to determine if LT can be an effective adjuvant for rectally delivered antigens.
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PMID:Safety and efficacy of E coli enterotoxin adjuvant for urease-based rectal immunization against Helicobacter pylori. 1245 Jun 94

H pylori infection is highly prevalent in asymptomatic children and it varies between countries and often within a country as well. Initial infection probably occurs at an early age and prevalence increases with age. Ethnic and racial factors, socio-economic status and living conditions affect the prevalence of infection. Long term population based studies are needed to identify the exact prevalence and clinical significance in Indian children. There is strong evidence for an association between H pylori infection and antral gastritis and duodenal ulcer disease in children, but it's association with recurrent abdominal pain needs further evaluation. Diagnostic tests for H pylori are based either on direct demonstration of the organism or indirectly by detecting a by-product (of the urease reaction) or by demonstrating antibodies. Histopathological identification of H pylori in [table: see text] antral biopsy specimen is by far the best method and is currently regarded as gold standard. Serological tests detecting IgG and IgA are possible tools for diagnosis but have many drawbacks. They may be useful for population surveys where invasive tests are not feasible. These tests should be standardized for the population for which they are going to be used. Urea breath test is a highly sensitive non-invasive test for H pylori infection and can be used even in a field setting. Urea Breath test needs to be standardized in tropical countries with high rates of dental colonization and duodenal microbial contamination. Newer diagnostic tests for H pylori infection are emerging but most have not been validated in various populations. Routine testing for H pylori is not indicated in children or adults. The decision to perform a diagnostic test has often to be linked with a therapeutic proposal. The only condition for which H pylori treatment is indicated is duodenal ulcer which is very uncommon in children. Treatment for RAP or even dyspepsia is not warranted on clinical grounds. There are several treatment regimens available, but it appears that at least three drugs including two antibiotics and a proton pump inhibitor are required for satisfactory eradication. In developing countries where the prevalence of infection is very high, well-planned double blind cross-over studies are needed before an evidence based answer can be provided for an optimal therapeutic strategy.
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PMID:Helicobacter pylori infection in children: a review. 1497 81

Helicobacter-induced gastritis is considered nowadays an epidemic, the prevalence of which is one of the highest world-wide (70%), with as much as 40% of the population in industrialized countries. Helicobacter pylori (H. pylori) antigens (Ag) capable to elicit a protective immune response in animal models have been identified, but these antigens have not been shown to be strongly immunogenic when administered to humans. Due to their stability in the gastric environment and avidity, passive administration of secretory immunoglobulin A (SIgA) antibodies (Ab) targeting protective Ag might be particularly relevant as a substitute or complement to current therapies. To this aim, we have designed expression vectors to convert a scFv polypeptide specific for H. pylori urease subunit A into human IgG, polymeric IgA (IgAp/d) and SIgA. Purified proteins show proper binding characteristics toward both the native and denatured forms of H. pylori urease. The direct comparison between different isotype and molecular forms, but of unique specificity, demonstrates that SIgA and IgAp/d are more efficient in blocking free and H. pylori-associated urease than IgG and scFv. We conclude that the expression system reported herein will represent a valuable tool to produce human SIgA Ab of multiple specificities against H. pylori antigens involved in colonization and persistence.
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PMID:Human polymeric IgA is superior to IgG and single-chain Fv of the same monoclonal specificity to inhibit urease activity associated with Helicobacter pylori. 1530 63

The acute antibody and T-cell immune response to Helicobacter pylori infection in humans has not been studied systematically. Serum from H. pylori-naive volunteers challenged with H. pylori and cured after 4 or 12 weeks was tested by enzyme-linked immunosorbent assays for anti-H. pylori-specific immunoglobulin M (IgM) and IgA established using bacterial lysates from homologous (the infecting strain) and heterologous H. pylori. Proteins recognized by IgM antibody were identified by mass spectrometry of immunoreactive bands separated by two-dimensional gel electrophoresis. Mucosal T-cell subsets (CD4, CD8, CD3, and CD30 cells) were assessed by immunohistochemistry. All 18 infected volunteers developed H. pylori-specific IgM responses to both homologous or heterologous H. pylori antigens. H. pylori antigens reacted with IgM antibody at 4 weeks postinfection. IgM Western blotting showed immunoreactivity of postinfection serum samples to multiple H. pylori proteins with molecular weights ranging between 9,000 (9K) to 150K with homologous strains but only a 70K band using heterologous antigens. Two-dimensional electrophoresis demonstrated that production of H. pylori-specific IgM antibodies was elicited by H. pylori flagellins A and B, urease B, ABC transporter binding protein, heat shock protein 70 (DnaK), and alkyl hydroperoxide reductase. Mucosal CD3, CD4, and CD8 T-cell numbers increased following infection. IgM antibody responses were detected to a range of homologous H. pylori antigens 2 to 4 weeks postchallenge. The majority of H. pylori proteins were those involved in motility and colonization and may represent targets for vaccine development.
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PMID:B-cell and T-cell immune responses to experimental Helicobacter pylori infection in humans. 1584 7

We assessed the sensitivity and specificity of H. pylori IgG and IgA with a commercial immunoassay performed in Chile and a second non-commercial immunoassay performed in a reference laboratory in the United States, in serum of 80 children and adults referred for gastrointestinal endoscopies in a developing country. Overall, 56% of the patients were infected with H. pylori based on rapid urease test and staining techniques on gastric biopsies. When Receiver Operator Curves (ROC) were developed, the sensitivity and specificity were similar for IgG and IgA. Both immunoassays exhibited better specificity, positive and negative predictive value (NPV) in children than in adults when cut-off values were corrected according to the local population than when they were assessed using the cut-off values pre-defined in other populations. These results underline the need to establish more precise cut-off values corrected in the local populations where assessments of antibodies as diagnostic markers of H. pylori infection are planning.
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PMID:Relevance of adjusted cut-off values in commercial serological immunoassays for Helicobacter pylori infection in children. 1624 Feb 23

In the present study, we evaluated the capacity of Helicobacter pylori adhesin A (HpaA), a H. pylori specific colonization factor, to induce therapeutic protection against H. pylori infection in mice. We found that oral immunization of H. pylori infected mice with HpaA induced protection, i.e. significant reduction in bacterial load in the stomach. This was even more pronounced when a combination of HpaA and urease was used. The protection was strongly related to specific mucosal CD4+ T cell responses with a Th1 profile as well as to mucosal IgA responses locally in the stomach. These findings suggest that HpaA is a promising vaccine candidate antigen for use in a therapeutic vaccine against H. pylori.
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PMID:Oral immunization with HpaA affords therapeutic protective immunity against H. pylori that is reflected by specific mucosal immune responses. 1723 98

Helicobacter pylori has to counteract acidity during colonization in the stomach. The most important region for the enzymic activity of H. pylori urease, consisting of 138 aa (ureB138), was determined by a comparison of the homology of amino acid sequences, and a structural analysis, between urease of H. pylori and various other species. This region was expressed in Escherichia coli as a fusion protein with glutathione S-transferase (GST), which was cleaved by PreScission protease between the GST moiety and ureB138. The ureB138 protein was then purified by gel filtration. The polyclonal antibody (pAb) induced by immunization with the purified ureB138 could suppress urease activity by about 50 %, while the pAb against the H. pylori urease did not show any inhibitory effect at all. Immunohistochemical analysis indicated that the ureB138-specific pAb specifically recognized the H. pylori infecting human gastric tissues. The effects of vaccination of recombinant ureB138 against infection by this organism were also examined. Specific IgG and IgA antibodies against H. pylori urease were induced in the serum of mice immunized with ureB138. A reduction in the number of colonizing H. pylori was observed in mice treated with ureB138 compared to ones treated with BSA and infection control mice. In the protected mice, severe gastritis characterized by marked infiltration of mononuclear cells was noted compared with the gastritis observed in unprotected mice. Immunohistochemical staining for IgA in gastric mucosa showed that the number of mice positively stained with IgA was significantly higher in ureB138-vaccinated mice than in non-vaccinated mice. This indicates that local IgA antibody and severe post-immunization gastritis correlate well with the protection of mice against H. pylori infection.
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PMID:Effects of vaccination by a recombinant antigen ureB138 (a segment of the beta-subunit of urease) against Helicobacter pylori infection. 1751 Feb 73

The effect of dietary therapy with a human Lactobacillus strain GG (ATCC 53103), bovine colostrum, or bovine immune colostrum with specific antibodies against anaerobic intestinal bacteria on gut defence mechanisms were studied in juvenile chronic arthritis. Thirty patients with juvenile chronic arthritis were randomly allocated to receive a freeze-dried powder of Lactobacillus GG, or bovine colostrum, or bovine immune colostrum, for a two-week period. Immunologic and non-immunologic gut defence mechanisms were indirectly investigated in blood and faecal samples. In patients receiving Lactobacillus GG, the median (interquartile range) frequency of immunoglobulin-secreting cells, determined by enzyme-linked immunospot assay, increased in the IgA class from 1840 (690-2530) to 3480 (1030-13 170)/10(6) cells; p=0.02. Likewise the median (interquartile range) frequency of specific antibody-secreting cells against dietary antigens increased during the Lactobacillus GG therapy in the IgM class from 3.8 (1.4-5.0) to 11.2 (5.0-30.0)/10(6) cells; p=0.02. In addition, Lactobacillus GG therapy decreased the median (interquartile range) activity of faecal urease, which has been associated with mucosal tissue damage, from 40.3 (21.7-54.3) to 28.6 (24.5-49.4) nmol. min(-1) (mg protein)(-1); p=0.10, while, in patients receiving bovine colostrum, faecal urease activity increased (from 42.2 to 80.6; p=0.04). All findings were transient. We suggest that gut defence mechanisms are disturbed in juvenile chronic arthritis and we further suggest that orally administered Lactobacillus GG has a potential to reinforce the mucosal barrier mechanisms in juvenile chronic arthritis.
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PMID:Dietary therapy with Lactobacillus GG, bovine colostrum or bovine immune colostrum in patients with juvenile chronic arthritis: evaluation of effect on gut defence mechanisms. 1763 32

In this study, the effects of alginate modification on absorption properties of FITC-BSA loaded TMC nanoparticles were investigated on an in vitro model of GI epithelium (Caco-2 cells). The feasibility of applying TMC nanoparticles loaded with a model vaccine urease in oral vaccination was also studied. Alginate modified TMC nanoparticles showed higher FITC-BSA permeate efficiency than non-modified TMC nanoparticles. However, alginate modification barely had any effect on TMC nanoparticles' property of decreasing TEER or enhancing drug paracellular transport. Mice s.c. immunized with urease loaded TMC nanoparticles showed highest systematic immune response (IgG levels) but the lowest mucosal response (secretory IgA levels). In the contrast, mice i.g. immunized with urease loaded TMC nanoparticles showed much higher antibody titers of both IgG and secretory IgA than those with urease solution or urease co-administrated with TMC solution. These results indicated that TMC nanoparticles are potential carriers for oral protein and vaccine delivery.
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PMID:In vitro and in vivo study of N-trimethyl chitosan nanoparticles for oral protein delivery. 1782 6

A new fusion peptide CtUBE of cholera toxin B subunit and Helicobacter pylori urease B subunit epitope was expressed in Escherichia coli. With this fusion peptide, an oral liposome vaccine against H. pylori infection was prepared and evaluated in BALB/c mice. Based on the results of urease tests, quantitation of culturable bacteria colonies in mice stomachs and histological identification of gastritis, the mice were protected significantly after intragastric vaccination with this CtUBE liposome vaccine, which increased the content levels of specific anti-urease serum IgG and mucosal IgA for both prophylactic and therapeutic vaccination protocols. These results showed that the fusion peptide CtUBE retained immunogenicity and could be used as antigen in the development of an oral vaccine against H. pylori infection.
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PMID:Oral vaccination with liposome-encapsulated recombinant fusion peptide of urease B epitope and cholera toxin B subunit affords prophylactic and therapeutic effects against H. pylori infection in BALB/c mice. 1791 5


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