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D Vaira

Publications and source records attributed to D Vaira.

At least 73 records · Page 4Linked to original sources
PubMed1999

Helicobacter pylori and type 1 diabetes mellitus in children.

BACKGROUND: Helicobacter pylori is a recognized gastroduodenal pathogen and H. pylori infection is one of the most common bacterial infections, usually acquired during childhood. However, diabetes mellitus is characterized by an increased susceptibility to infections. METHODS: We compared the prevalence of H. pylori infection as well as cytotoxin-associated gene A-CagA-and vacuolating cytotoxin gene A-VacA-positivity in 103 children and adolescents with type 1 diabetes mellitus and in 236 nondiabetic children. We used a novel Recombinant ImmunoBlot Assay-Strip (RIBA SIA) with individual band for whole H. pylori lysate and recombinant CagA and VacA. RESULTS: H. pylori-positive subjects, both diabetics and controls, were significantly older than negative subjects. In the whole group of diabetic patients the prevalence of each of the three reactivities was higher than in control subjects, reaching significance only for lysate. Only diabetic patients over 12 years of age, with a longer disease duration, had a higher prevalence of positive cases, although not significantly so. CONCLUSIONS: In the first few years of disease, diabetic children do not differ from the nondiabetic population. Subsequently they show an H. pylori seroprevalence tendentially higher than that of controls of the same age. Therefore, H. pylori infection acquired in childhood and lasting several years, could be one of the causes of chronic atrophic gastritis, which is more frequent in longstanding diabetes mellitus.

Adolescent↗
PubMed1999

New immunological assays for the diagnosis of Helicobacter pylori infection.

There are several types of immunological tests available for the diagnosis and management of Helicobacter pylori infection. Most commercially available serological kits use the enzyme linked immunosorbent assay (ELISA) test format. Originally the kits used crude antigen preparations although many of the newer kits use a more purified antigen preparation, with often increased specificity but lower sensitivity. Near patient test kits are based either on latex agglutination or immunochromatography. Generally they have low sensitivities compared with laboratory tests. Western blotting, ELISA, and recombinant immunoblot assays (RIBA) have also been developed into commercially available kits and can be used to indicate the presence of specific virulence markers. An antigen detection kit has been developed for the detection of Helicobacter pylori in faeces. Immunological reagents have also been combined with other diagnostic modalities to develop immunohistochemical stains and DNA immunoassays. Helicobacter pylori is now recognised as the cause of gastritis and most cases of peptic ulcer disease (PUD); its long term carriage increases the risk of gastric adenocarcinoma sixfold and it is designated as a class I carcinogen. H pylori has also been implicated as a cause of gastric mucosa associated lymphoid tissue lymphomas. Its relation to non-ulcer dyspepsia remains controversial. Additionally, long term carriage of the organism may be associated with short stature in young girls and, in the general population, as a possible risk factor for the development of vasospastic disorders and possibly skin immunopathology such as urticaria. With the recognition of H pylori as an important human pathogen, it has become one of the growing number of organisms to have its complete genome sequence mapped. Serology is an important method of determining colonisation status and can be used for diagnosis, as a screening procedure, or to follow the efficacy of eradication regimens. Most serological assays are in the ELISA format although some are based on the latex agglutination reaction. These latter are used principally as near patient assays. Most assays detect IgG in serum although some detect serum IgA. More recently developed assays detect IgA in saliva and the production of affinity purified antibodies has led to the development of an antigen detection assay for faecal specimens. Serological reagents have also been used in immunocytochemistry and to speed up the detection of amplified products of the polymerase chain reaction (PCR)-DNA immunoassays.

Helicobacter Infections↗
PubMed1999

Food allergy and Helicobacter pylori infection.

BACKGROUND: Most antigens reach the immune system through mucosae. Gastrointestinal mucosa is a barrier for alimentary antigens. Inflammatory processes, such as Helicobacter pylori-associated gastritis, could alter the integrity of the gastric barrier, increase the mucosal permeability, and enhance crossing of food antigens which may stimulate allergic reactions. PURPOSE: The aim of this study was to establish whether patients with symptomatic food allergy and detectable immunoglobulin E (IgE) to alimentary antigens were infected by Helicobacter pylori more often than controls, and to determine the phenotype of the infecting Helicobacter pylori. PATIENTS AND METHODS: Thirty-eight consecutive patients with symptomatic food allergy and serum IgE to alimentary antigens, and 53 consecutive age-matched controls (subjects without food allergy and detectable levels of IgE anti-alimentary antigens) living in the same area and attending the same institution were investigated serologically to determine the prevalence of Helicobacter pylori infection, and an immune response to CagA, a marker of the most pathogenic strains. IgE to alimentary allergens were measured by a commercial kit. RESULTS: The prevalence of Helicobacter pylori infection in patients with food allergy and controls was similar (42.1% and 47.1%, respectively). Anti-CagA antibodies in Helicobacter pylori-infected persons were detected in 62.5% of patients with food allergy, and 28.0% of controls (p = 0.030, odds ratio = 4.29, RR = 2.23). The mean IgE level to the most common alimentary antigens was increased in CagA-positive, with respect to the CagA-negative, patients. CONCLUSIONS: The enhanced mucosal and inflammatory lesions commonly found in individuals infected by CagA-positive Helicobacter pylori strains could increase the epithelial permeability and render non-selective the passage of allergens which, in atopic persons, could directly stimulate an IgE response. Infection by CagA-positive Helicobacter pylori may increase the risk of food allergy.

Adolescent↗
PubMed1999

The infection by Helicobacter pylori strains expressing CagA is highly prevalent in women with autoimmune thyroid disorders.

UNLABELLED: H. pylori infection is putatively associated with extra-digestive disorders and may also play a role in the development of autoimmune thyroid diseases (ATD). It was recently found that monoclonal antibodies to an H. pylori strain with cagA-positivity reacted with follicular cells of the thyroid gland, and that an H. pylori organism possessing the cag pathogenicity island carried a gene encoding for an endogenous peroxidase. The aims of this study was (1); To ascertain whether the infection by strains endowed with an increased inflammatory potential (those expressing CagA) could further enhance the risk of developing ATD (2); To verify the possible existence of an immune cross-reactivity between autoantibodies to peroxidase and thyroglobulin and H. pylori antigens (3). To establish whether thyroid colloid antigens could cross-react with an anti-H. pylori serum. The study was partly designed retrospectively. We examined 41 consecutive women with ATD, and, as a control, 33 consecutive age- and socio-economic class-matched women without autoimmune thyroid disorders, living in the same area as patients, occurred at the same institution in the same period (six months). Both patients and controls were examined serologically for H. pylori infection and CagA status by Western blotting. Some serum samples were absorbed with H. pylori to determine whether the antibody levels decreased. Colloid proteins were resolved electrophoretically and matched with a hyperimmune serum raised in rabbits against a CagA-positive H. pylori. Thirty-two patients (78.0%) tested seropositive for H. pylori infection, vs. 16 controls (48.4%) (P = 0.008, OR = 3.78, RR = 1.61). The prevalence of anti-CagA antibodies was 71.8% in infected patients, and 50% in infected controls (P = 0.161, n.s.). The overall prevalence of infection by CagA-positive H. pylori was significantly higher in patients with ATD (23/41, or 56.0%) than that in controls (8/33, or 24.2%) (P = 0.006, OR = 3.99, RR = 2.31). The other tests gave negative or inexplicable results. IN CONCLUSION: CagA-positive H. pylori infection increases the risk of ATD development.

Adolescent↗
PubMed1998

Most Helicobacter pylori-infected patients have specific antibodies, and some also have H. pylori antigens and genomic material in bile: is it a risk factor for gallstone formation?

Bile may contain a 130-kDa protein endowed with aminopeptidase activity and the ability to promote cholesterol crystallisation. As >90% of H. pylori strains have a similar peptidase activity, and half the isolates express a 110- to 140-kDa antigen, the CagA protein, we investigated a possible association between H. pylori infection and gallstones, and the presence in bile samples of factors related to H. pylori that could increase cholesterol crystallization. The prevalence of H. pylori infection was 82.1% in 112 patients with gallstones and 80.3% in 112 controls (NS). Fifteen bile samples out of 23 specimens from infected patients (65.2%) contained anti-CagA antibodies. A approximately 60-kDa antigen only reacting with an anti-CagA antibody was found in five bile samples (21.7%) from 23 infected patients. One bile sample (4.1%) contained ureA and cagA genes of H. pylori. The homology of CagA with the N-terminal sequence of aminopeptidase N was very low. We concluded that the presence of specific antibody to H. pylori in most bile samples tested and of an H. pylori putative antigen in a discrete number of cases may represent factors that increase the risk of gallstone formation.

Antibodies, Bacterial↗
PubMed1998

Clinical significance of Helicobacter pylori seropositivity and seronegativity in asymptomatic blood donors.

To determine the clinical significance of Helicobacter pylori seropositivity and seronegativity in healthy blood donors, we carried out a serological evaluation of Helicobacter pylori status and endoscopy in a healthy blood donors population. In all, 1010 donors were screened for Helicobacter pylori by IgG ELISA and assessed for pepsinogen I and gastrin levels by RIA; 298 IgG seropositive and 61 seronegative subjects underwent endoscopy with biopsies. Of 359, 165 were also tested for CagA by western blotting. Of the 298 IgG seropositives, 274 were shown to be infected on biopsy testing. Endoscopy revealed 70 peptic ulcers, 41 cases of erosive duodenitis, and two gastric cancers. In all 105 seropositive donors were tested for CagA and 69 were CagA positive [34/58 gastritis (58.6%), 24/35 duodenal ulcer (68.6%) and 11/12 gastric ulcer (91.6%)]. Histologically active/chronic gastritis was associated with CagA: 88.4% vs 50% (CagA seropositive vs seronegative). Of the 61 IgG seronegatives, 59 were negative on biopsy testing. At endoscopy three had duodenitis. Of the 60/61 IgG seronegatives tested for CagA, one had a moderate reaction. Duodenal ulcer donors showed higher pepsinogen I levels than donors without duodenal ulcers (97.7 microg/ml vs 80.9 microg/ml respectively). Screening for Helicobacter pylori and anti-CagA seropositivity and pepsinogen I can identify individuals likely to have gastroduodenal pathology even in the absence of symptoms.

Adolescent↗
PubMed1998

cagA positive and negative Helicobacter pylori strains are simultaneously present in the stomach of most patients with non-ulcer dyspepsia: relevance to histological damage.

BACKGROUND/AIMS: Infection with Helicobacter pylori strains harbouring the cagA gene (cagA+) is associated with an increased risk of developing peptic ulcer and gastric cancer. The aim of this study was to assess whether H pylori isolates with different cagA status were present in patients with non-ulcer dyspepsia, and whether a variable cagA status is relevant to histological gastric mucosal damage and glandular cell proliferation. METHODS: Well separated H pylori colonies (between 2 and 25) from primary plates, per gastric area, for each of 19 patients with non-ulcer dyspepsia were examined for cagA by hybridisation. Western blotting was used to examine both representative colonies for CagA expression and the patients' sera for antibody response to CagA. Glandular gastric cell proliferation was assessed immunohistochemically. RESULTS: Of the 747 colonies examined, 45.3% were cagA+. All colonies from four patients were cagA+, and all colonies from two patients were cagA-. In 13 patients (68%) both cagA+ and cagA- colonies were found. CagA expression of isolates corresponded to their cagA status. H pylori strains with different CagA molecular masses were present in three patients. Results based on all 19 patients studied showed that the prevalence of cagA+ colonies in areas with mucosal atrophy associated or not with intestinal metaplasia (67.9%) was significantly higher than in normal mucosa (44.7%) and mucosa from patients with chronic gastritis (44.0%) (p < 0.001). High levels of cell proliferation were associated with histological atrophy with or without intestinal metaplasia, but not with the possession of cagA by organisms colonising the same mucosal sites. CONCLUSIONS: Most patients with nonulcer dyspepsia are infected by both cagA+ and cagA- H pylori colonies. The cagA status of infecting organisms may play a role in the development of atrophy and intestinal metaplasia.

Adult↗
PubMed1998

Blood tests in the management of Helicobacter pylori infection. Italian Helicobacter pylori Study Group.

There are three main types of blood test available for the management of Helicobacter pylori infection: those that detect an antibody response; tests of the pathophysiological state of the stomach; and those that indicate an active infection. Enzyme linked immunosorbent assay (ELISA) based kits are the most numerous of the commercially available tests. Originally the kits used crude antigen preparations but many of the newer kits use a more purified antigen preparation giving increased specificity but a lower sensitivity. The sensitivity, specificity, and predictive values of the tests can also be affected by the population under test and coexistent disease in the patients. Near patient test kits are based on either latex agglutination or immunochromatography. Generally, they have low sensitivities compared with laboratory tests. Commercial western blotting kits have also been developed and are used to detect the presence of specific virulence markers. The exact role of serology in the management of Helicobacter infection has still to be defined, although there is evidence that, used as a screening procedure, it can reduce endoscopy cost and workload. Gastrin and pepsinogen blood concentrations may provide valuable information on the pathophysiological state of the stomach--for example, the presence of inflammation or gastric atrophy. A combination of serology and serum concentrations of gastrin and pepsinogen may be used effectively to detect serious gastroduodenal disease in patients.

Antibodies, Bacterial↗
PubMed1998

The European meeting on Helicobacter pylori: therapeutic news from Lisbon.

The current standard of Helicobacter pylori treatment has been confirmed by the studies presented at the Lisbon workshop--that is, one of three one week proton pump inhibitor (PPI) based triple therapies comprising a twice daily standard dose of a PPI in combination with two of the following antimicrobial agents: clarithromycin, amoxycillin, or a nitromidazole. This standard of treatment is also highly efficacious and cost-effective in routine community practice. The current data confirm the equivalence of ranitidine bismuth citrate to PPI, and of azithromycin to clarithromycin. The optimum dose for azithromycin has not yet been defined. There is some evidence that in certain regions treatment for more than one week may be advantageous. The reasons are still not clear. However, microbial resistance may be one important factor, as it has a substantial effect on treatment outcome and the prevalence of resistance varies considerably in different areas. The negative impact of resistance is increased by shortening the treatment time. At present, there is no general necessity to test for resistance before treatment. However, before selection of a second line treatment, testing for resistance is recommended.

Anti-Bacterial Agents↗
PubMed1998

Therapeutic news on Helicobacter pylori from Budapest and Wien.

Helicobacter pylori is the most common infection in the world and is associated with some of the most prevalent gastroduodenal diseases. There is now considerable evidence that Helicobacter pylori eradication not only heals duodenal ulcer, but also prevents ulcer recurrences and probably ulcer complication. It is, therefore, universally accepted that, all patients with duodenal ulcer disease should receive eradication therapy. This review represents an attempt to summarize and analyse all the regimens proposed in September at the last International Meetings in Budapest and Wien in which different anti Helicobacter pylori regimens have been used. Despite the large number of clinical trials which had been performed, no significant advances have been made in relation to Helicobacter pylori therapy, so the "optimal" eradication treatment still remains a matter of debate. More than 10,000 patients were treated and most of them (around 5000) were found to have peptic ulcer disease which represents no more than 10-15% of our endoscopic findings. The proton pump inhibitor regimens are definitely the most representative drug policy appearing in the literature and despite several attempts (proton pump inhibitor given for less, one, or more than one week) the short one-week regimen (The Maastricht regimen) has been recognized as the most promising treatment.

Anti-Bacterial Agents↗
PubMed1998

Routes of transmission of Helicobacter pylori infection.

Helicobacter pylori is an important gastroduodenal pathogen, which has been recognized as a Class I carcinogen factor for gastric cancer and gastric mucosa associated lymphoid tissue lymphomas. In spite of the world-wide spread of the infection, the route of transmission is still not known. We reviewed data from several sero-epidemiological studies and aimed to identify potential sources of Helicobacter pylori infection. Available evidence strongly suggests an inverse correlation between socio-economic status and prevalence of Helicobacter pylori. The infection is acquired mostly during childhood in the third world, but is rare in children in developed countries, where the prevalence of Helicobacter pylori increases with age. Following the detection of the bacterium in saliva, faeces, and gastric juice, oral-oral or faecal-oral transmission and iatrogenic spread, through the use of unsterile endoscopes, have been proposed as possible routes of infection. Helicobacter pylori has also been found in some domestic cats, but at present, the risk of infection from these animals appears slight. The mode of transmission of Helicobacter pylori, as is yet, not known. Available information support the hypothesis of spread through close personal contact, considering humans as the only significant reservoir of infection.

Age Factors↗
PubMed1998

Helicobacter pylori and diminished growth in children: is it simply a marker of deprivation?

Helicobacter pylori is an accepted gastroduodenal pathogen and has recently been investigated for possible implications in non gastroenterological diseases such as growth impairment coronary heart disease and diabetes. Infection by cytotoxic, i.e., CagA or VacA positive strains seems more likely to lead to more serious gastroduodenal diseases compared to infection by non cytotoxic strains, but the possible role of CagA or VacA positive strains in non gastroenterological diseases has not been investigated. Aim of the present study was to evaluate the prevalence of Helicobacter pylori infection as well as CagA and VacA positivity in three paediatric populations auxologically normal, hyposomic and diabetic children. Sera from a total of 522 children (auxologically normal: 246, hyposomic: 164, diabetic: 112) were analyzed by a novel Recombinant ImmunoBlot Assay-Strip Immunoblot Assay--RIBA SIA--which contain individual band for whole Helicobacter pylori lysate and recombinant CagA and VacA. The overall seroprevalence of reactivities against Helicobacter pylori lysate, CagA and VacA were: 7.3%, 9.3%, 6.9% vs 11.6%, 7.9%, 8.5% vs 14.3%, 13.4%, 8% (p = NS) in auxologically normal, hyposomic and diabetic children, respectively. Summarizing, we found a similar prevalence of reactivity against both whole Helicobacter pylori lysate as well as recombinant CagA and VacA between auxologically normal, hyposomic and diabetic children. Our data do not support a possible role of Helicobacter pylori in diminished growth in children.

Adolescent↗
PubMed1998

["Hepatitis" A virus g: myth or reality? VHG/GBH-C: diagnosis, epidemiology, transfusion risk, and pathogenicity].

The recently discovered G virus (also called either GBV-C or HGV) is transmitted by blood transfusion as well as by sexual intercourse. The global prevalence of GBV-C is high, not only in those groups classically known to be exposed to parenteral risks (i.v. drug users, polytransfused patients), but also in the blood donors population. The diagnosis of active infection lies on the search of GBV-C RNA by Polymerase Chain Reaction whereas that of resolved (past) infection lies on the presence of specific antibodies. Till now, it has not been possible to correlate convincingly the presence of GBV-C RNA with any acute or chronic hepatopathy. On the contrary, a lot of arguments tend to suggest that the GBV-C is not pathogenic for the liver, although some modes of transmission are common with those of other (known and probably not known) hepatotropic viruses. According to the actual knowledge of the consequences of GBV-C infection, it appears as non relevant to instaure a systematic screening of this new virus in blood donors.

Flaviviridae↗
PubMed1997

What is the role of Helicobacter pylori in complicated ulcer disease?

The role of Helicobacter pylori in the pathogenesis of duodenal and gastric ulcer and ulcer recurrence is widely known. Bleeding, perforation, and obstruction represent the most serious, potentially life-threatening manifestations of ulcer disease (hemorrhage in 15%-20%). The lifetime prevalence of perforation and obstruction is much lower (approximately 5% and 2%, respectively). Despite improved diagnostic and therapeutic options, bleeding-related mortality rates remain at 6%-7% in the United States and between 4% and 14% in Europe. H. pylori and nonsteroidal anti-inflammatory drugs are now recognized as the two primary causes of ulcer disease. Eradication of H. pylori in patients with uncomplicated ulcers results in recurrence rates of < 10%, suggesting that eradication of H. pylori in patients with bleeding ulcers may virtually prevent recurrence of both the disease and its complications. Although the prevalence of H. pylori infection is almost 100% in duodenal and 80%-90% in gastric ulcer patients not using nonsteroidal anti-inflammatory drugs, the prevalence of the organism in bleeding duodenal and gastric ulcers does not reach 70% and 60%, respectively, which may be due to false-negative test results.

Anti-Ulcer Agents↗