Biomedical subjects

A M Hirschl

Publications and source records attributed to A M Hirschl.

At least 19 recordsLinked to original sources

PubMed2001

Impact of bacteria in dairy products and of the intestinal microflora on the genotoxic and carcinogenic effects of heterocyclic aromatic amines.

This article gives a short overview on the present state of knowledge of the effects of the intestinal microflora on the health hazards of heterocyclic aromatic amines (HAs). Results of single cell gel electrophoresis assays with conventional, germ free and human flora associated rats indicate that the presence of intestinal microorganisms strongly enhances the induction of DNA-damage in colon and liver cells by IQ. Furthermore, it was found that supplementation of the feed with Lactobacilli attenuates the induction of colon cancer by this same amine. These recent findings suggest that the intestinal microflora and lactic acid bacilli in dairy products strongly affect the health risks of HAs. Nevertheless, most previous experiments with HAs focused on the involvement of mammalian enzymes in the biotransformation of these compounds and only a few articles are available which concern interactions of bacteria with HAs. Some of these studies suggested that the formation of directly mutagenic hydroxy-metabolites of the amines by fecal bacteria might be an important activation pathway but it turned out that the hydroxy-derivative of IQ is not genotoxic in mammalian cells and does not cause colon cancer in laboratory rodents. There is some evidence that hydrolysis of HA-metabolites by bacterial ss-glucuronidase might play a role in the activation of HAs but experimental data are scarce and no firm conclusions can be drawn at present. The most important detoxification mechanism appears to be the direct binding of the HAs to the cell walls of certain bacterial strains contained in fermented foods. It was shown that these effects do also take place under physiologically relevant conditions. Overall, it seems that intestinal bacteria play a key role in the activation and detoxification of HAs which has been an area of research long ignored. The elucidation of these mechanisms may enable the development of biomarkers for colon cancer risk and nutritional strategies of protection.

Amines↗

PubMed2001

Urease prevents adherence of Helicobacter pylori to Kato III gastric epithelial cells.

The role of urease in Helicobacter pylori adherence to and internalization by Kato III cells was investigated. Kato III cells were incubated with wild-type strains (N6 or P1), with isogenic mutants lacking urease (N6ureB::TnKm or P1ureA::TnMax5) or producing the inactive apoprotein (N6ureG::TnKm), and with urease-positive clones recovered after complementation of N6ureB::TnKm with ureAB. Bacteria were stained with the green fluorescent dye PKH2, and the bacteria load of cells was analyzed by flow cytometry. With mutants lacking urease, the bacteria load was considerably increased, in comparison with the corresponding parental strains (P<.001). With clone K2(3), producing larger amounts of urease than N6, a significant reduction of bacteria load was observed, in comparison with the wild type (P<.001). N6ureG::TnKm showed adherence characteristics similar to those of N6. The role of urease in internalization was not clear. Thus, urease significantly inhibits H. pylori adherence to Kato III cells by a mechanism largely independent of enzymatic activity.

Bacterial Adhesion↗

PubMed2001

Multicenter comparison trial of DNA extraction methods and PCR assays for detection of Chlamydia pneumoniae in endarterectomy specimens.

The reported rate of detection of Chlamydia pneumoniae DNA within atherosclerotic lesions by PCR varies between 0 and 100%. In this study, identical sets of coded experimental atheroma samples (n = 15) and spiked controls (n = 5) were analyzed by 16 test methods in nine centers by means of PCR. The positive controls were correctly identified to levels of 1, 0.1, and 0.01 inclusion bodies of C. pneumoniae/ml of tissue homogenate by 16 (100%), 11 (69%), and 3 (19%) of the test methods, respectively. Three out of 16 negative controls (19%) were rated positive. Positivity rates for atheroma samples varied between 0 and 60% for the different test methods, with the maximum concordant result for positivity being only 25% for one carotid artery sample. There was no consistent pattern of positive results among the various laboratories, and there was no correlation between the detection rates and the sensitivity of the assay used.

Arteriosclerosis↗

PubMed2000

Purification of surface-associated urease from Helicobacter pylori.

Helicobacter pylori colonizes the human gastric mucosa and produces large amounts of urease. The enzyme was extracted from the bacteria by distilled water and purified by gel-permeation (Sephacryl S-300), anion-exchange chromatography (Mono Q) and a second gel-permeation (Superdex 200). Urease enzyme activity was detected with a spectrophotometic assay based on phenol red. The optimal pH for anion-exchange was 6.9. The recovery of urease was 55-75%, purity 93-98% and the overall protein recovery 0.8-1.4%. The urease in the final extract still had enzymatic activity and showed the typical subunits of Mr 66000 and Mr 30000 when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Blotting, Western↗

PubMed2000

Isolation and continuous growth of Chlamydia pneumoniae from arterectomy specimens.

For the purpose of collecting Chlamydia pneumoniae strains of vascular origin that could be grown continuously in vitro, a cell culture system has been established. Using different types of vascular specimens obtained from 38 patients, Chlamydia pneumoniae could be isolated in three (7.9%) cases. The strains were obtained from specimens of the carotid artery, the femoral artery and an infrarenal aneurysm of the abdominal aorta of three male atherosclerosis patients. Thus, viable Chlamydia pneumoniae strains are also present in vascular regions other than those hitherto described.

Aged↗

PubMed2000

Susceptibility testing of Candida species: comparison of NCCLS microdilution method with Fungitest.

Fungitest is a new commercially available and easy-to-perform breakpoint test system using six antifungal agents. We compared this test with a modified standard method described by the National Committee for Clinical Laboratory Standards (NCCLS). One hundred isolates of Candida species were tested with both methods. Based on the same breakpoints, the correlation of qualitative results between the reference method and Fungitest was high. Best results were obtained after incubation of Fungitest for 48 h. Overall agreement was high, an excellent correlation was given with amphotericin B and flucytosine (100% and 99%, respectively), whereas itraconazole showed only 86% concordance. When Fungitest was read after 24 h the agreement was lower ranging from 100% to 75%. Some of the breakpoints used with Fungitest differ from the breakpoints recommended by NCCLS, whereas others have not been elaborated by the NCCLS. The adaptation of Fungitest breakpoints to NCCLS and determination of further breakpoints have to be discussed before Fungitest can be recommended for routine use.

Amphotericin B↗

PubMed2000

[Diagnosis of Helicobacter pylori infections].

Hardly any other bacterial infection can be diagnosed with a similar variety of non-invasive and invasive tests as infection with H. pylori. Efficacy and specificity of well-proven tests such as urease test in biopsy specimens, histology, culture, and 13C breath test have been uniformly evidenced in numerous studies. Novel tests include molecular microbiological procedures, providing new opportunities for rapid detection of virulence factors and resistance genes, as well as antigen detection in feces. Though some open questions still need to be clarified, the latter test will gain major importance in the future. With the availability of the breath test and antigen detection in stool the need for the use of serological tests has been reduced, all the more so as the majority of the available quick tests have been shown to be of inadequate reliability. Well defined indications for the treatment of H. pylori infections are a major prerequisite for a reasonable use of this diagnostic armory.

Biopsy↗

PubMed2000

In vitro activities of linezolid alone and in combination with amoxicillin, clarithromycin, and metronidazole against Helicobacter pylori.

Linezolid was tested against 70 strains of Helicobacter pylori by the agar dilution method. The MIC range and MICs at which 50 and 90% of strains were inhibited were 8 to 64, 16, and 32 microgram/ml, respectively. With minimum and maximum fractional inhibitory concentration summation values of 0.31 and 2.50, respectively, the combination of linezolid with amoxicillin, clarithromycin, or metronidazole showed either partial synergy or indifference for the majority of strains.

Acetamides↗

PubMed2000

Two enzyme immunoassays and PCR for detection of Helicobacter pylori in stool specimens from pediatric patients before and after eradication therapy.

This study of pediatric patients was intended to determine the suitability of stool PCR and two antigen enzyme immunoassays (EIAs; Premier Platinum HpSA and the novel FemtoLab H. pylori), which detect Helicobacter pylori antigens in feces, as pretreatment diagnostic tools and especially as posttreatment control. Forty-nine H. pylori-infected children with dyspepsia received eradication therapy. Successful treatment was determined by a negative [(13)C]urea breath test 4 and 12 weeks after discontinuation of therapy. Fecal specimens were collected prior to eradication therapy as well as 4 weeks after the end of treatment. Successfully treated children delivered stool samples at 6, 8, and 12 weeks posttreatment also. Specimens were examined by seminested PCR and Premier Platinum HpSA and were reexamined by both EIAs as soon as FemtoLab H. pylori was available. In the first test series, the overall sensitivities of PCR and Premier Platinum HpSA were 93.0 and 91.1%, respectively. With specimens collected at 4 weeks after treatment, the respective specificities were 68.8 and 79.3%. After longer follow-up periods, however, they gradually increased to 100 and 96.9%, respectively. In the new test series, Premier Platinum HpSA delivered a considerably lower number of false-positive results (4 versus 18), indicating intertest variations. The overall test sensitivity was 94.6%, and the overall specificity was 97.5%. FemtoLab H. pylori showed an excellent performance with an overall sensitivity and specificity of 98.2 and 98.1%, respectively. Thus, in contrast to PCR, both EIAs were shown to be suitable for early posttreatment control.

Adolescent↗

PubMed1999

Diagnosis of Helicobacter pylori infection with a new non-invasive antigen-based assay. HpSA European study group.

BACKGROUND: Helicobacter pylori is a common human pathogen implicated in certain gastrointestinal diseases. In the search for new non-invasive techniques to diagnose H. pylori infection, we evaluated an EIA for H. pylori antigen in stool (HpSA). METHODS: In a prospective multicentre study, stool specimens from 501 patients (276 men, 225 women; age range 17-88 years, mean 52) undergoing gastroscopy in 11 centres throughout Europe were tested with HpSA and the carbon-13-urea breath test. At endoscopy, four biopsy samples were taken for histology (haematoxylin and eosin) and H. pylori detection (giemsa in both antrum and corpus, culture and rapid urease test). Patients were defined as positive for H. pylori if histology (antrum, corpus, or both) and urease test were positive, or if culture was positive. Patients classified as having H. pylori infection received an eradication regimen; 107 were reassessed 4 weeks after therapy. FINDINGS: Of 272 patients with H. pylori infection by the predefined criteria, 256 were positive by HpSA (sensitivity 94.1% [95% CI 90.6-96.6]). Of 219 patients without infection, 201 were negative by HpSA (specificity 91.8% [87.3-95.1]). INTERPRETATION: The stool assay was a reliable and easy-to-use tool for diagnosis of H. pylori infection. The test was accurate even shortly after treatment.

Adolescent↗

PubMed1999

Detection of Chlamydia pneumoniae DNA in atheromatous tissues by polymerase chain reaction.

Chlamydia pneumoniae is an important human respiratory pathogen. Recently, seroepidemiological data and the demonstration of chlamydial DNA or antigen within parts of atherosclerotic lesions have suggested a causal association between chlamydial infections and atherosclerosis. As the results obtained by different groups show considerable variations, we provide further data based on a highly specific and sensitive nested PCR method. Positivity was confirmed by nonradioactive hybridization with a specific probe, and sensitivity was determined by titration experiments. C. pneumoniae DNA was detected in 8/29 (28%) of carotid artery samples and 3/14 (21%) of aortic aneurysms.

Aged↗

PubMed1999

Enteroaggregative and enterotoxigenic Escherichia coli among isolates from patients with diarrhea in Austria.

In a 3-month prospective study among 203 Austrian outpatients with diarrhea, the role of pathogenic Escherichia coli and the use of the polymerase chain reaction in screening Escherichia coli isolates from clinical stool specimens were evaluated. Enteroaggregative Escherichia coli and enterotoxigenic Escherichia coli combined were identified as the second most frequent cause of diarrhea. Of a total of 85 bacterial pathogens isolated from 80 patients, 15 were pathogenic Escherichia coli, 13 enteroaggregative Escherichia coli and two enterotoxigenic Escherichia coli. Enteropathogenic, enteroinvasive, and enterohemorrhagic Escherichia coli isolates were not detected.

Adolescent↗

PubMed1999

Helicobacter pylori type I strains among Austrian and Portuguese patients with gastritis, peptic ulcer or gastric cancer.

The frequency of occurrence of Helicobacter pylori type I strains in isolates from Austria and Portugal and different polymerase chain reaction-based approaches to detect the cag pathogenicity island were assessed. Of the 41 Austrian strains, eight of 14 (57.2%) isolated from patients with gastritis, 14 of 19 (73.7%) from patients with peptic ulcer and eight of eight (100%) from patients with gastric cancer were type I strains. Among the Portuguese strains, eight of 14 (57.2%) isolated from patients with gastritis, ten of 12 (83.3%) from patients with peptic ulcer and five of 13 (38.5%) from patients with gastric cancer were classified as type I. Thus, Helicobacter pylori type I strains occur frequently in both populations but show no significant correlation with peptic ulcer disease. The prevalence of the type Igenotype in Austrian cancer patients, however, was significantly higher (P=0.007). The cagE-specific polymerase chain reaction was found to be a reliable and efficient method for detection of the cag pathogenicity island.

Adolescent↗

PubMed1999

Famotidine versus omeprazole in combination with clarithromycin and metronidazole for eradication of Helicobacter pylori--a randomized, controlled trial.

BACKGROUND: One-week low-dose triple therapy is currently considered the gold standard regimen for treatment of Helicobacter pylori infection. However, the mechanisms involved in the synergy between antibiotics and proton pump inhibitors are controversial. AIMS: To test the hypothesis that acid suppression represents the crucial mechanism by which the antibacterial activity of antibiotics can be enhanced, and to assess the impact of primary resistance on treatment outcome. METHODS: One hundred and twenty patients with H. pylori infection and duodenal ulcer, gastric ulcer or non-ulcer dyspepsia were randomly assigned to a 1 week course of either famotidine 80 mg b.d., clarithromycin 250 mg b.d. and metronidazole 500 mg b.d. (FCM group; n = 60) or omeprazole 20 mg o.d., clarithromycin 250 mg b.d. and metronidazole 500 mg b.d. (OCM group; n = 60). Gastroscopy was performed at baseline and 5 weeks after completion of treatment. H. pylori status was assessed by biopsy urease test, histology and culture. RESULTS: In the intention-to-treat analysis, eradication of H. pylori was achieved in 47 of 60 patients (78%; 95% CI: 66-88%) in the FCM group, compared to 44 of 60 patients (73%; 95% CI: 60-84%) in the OCM group (N.S.). Using per protocol analysis, eradication therapy was successful in 47 of 52 patients (90%; 95% CI: 79-97%) treated with FCM and 44 of 57 patients (77%; 95% CI: 64-87%) treated with OCM (N.S.). Primary metronidazole resistance was present in 27% and primary clarithromycin resistance in 8% of strains. Overall per protocol eradication rates in strains susceptible to both antibiotics and strains with isolated metronidazole resistance were 93% and 84%, respectively. No patient with clarithromycin resistance responded to treatment. CONCLUSIONS: High-dose famotidine and omeprazole, combined with clarithromycin and metronidazole, are equally effective for eradication of H. pylori. In 1-week low-dose triple therapy, metronidazole resistance has no major impact on eradication rates whereas clarithromycin resistance is associated with a poor treatment outcome.

Adult↗

PubMed1999

IgG subclass reactivity to human cardiac myosin in cardiomyopathy patients is indicative of a Th1-like autoimmune disease.

Studies performed in mice together with the demonstration of increased levels of heart-specific autoantibodies, cytokines and cytokine receptors in sera from cardiomyopathy (CMP) patients argued for a pathogenic role of autoimmune mechanisms in CMP. This study was designed to analyse the presence of IgG anti-heart antibodies in sera from patients suffering from hypertrophic and dilatative forms of CMP as well as from patients with ischaemic heart disease and healthy individuals. Patients' sera were analysed for IgG reactivity to Western-blotted extracts prepared from human epithelial and endothelial cells, heart and skeletal muscle specimens as well as from Streptococcus pyogenes. The IgG subclass (IgG1-4) reactivity to purified human cardiac myosin was analysed by ELISA. While sera from CMP patients and healthy individuals displayed comparable IgG reactivity to a variety of human proteins, cardiac myosin represented the prominent antigen detected strongly and preferentially by sera from CMP patients. Pronounced IgG anti-cardiac myosin reactivity was frequently found in sera from patients with dilatative CMP and reduced ventricular function. ELISA analyses revealed a prominent IgG2/IgG3 anti-cardiac myosin reactivity in CMP sera, indicating a preferential Th1-like immune response. Elevated anti-cytomegalovirus, anti-enterovirus IgG titres as well as IgG reactivity to nitrocellulose-blotted S. pyogenes proteins were also frequently observed in the group of CMP patients. If further work can support the hypothesis that autoreactivity to cardiac myosin represents a pathogenic factor in CMP, specific immunomodulation of this Th1- towards a Th2-like immune response may represent a promising therapeutic strategy for CMP.

Adolescent↗

PubMed1999

Influence of Helicobacter pylori infection on the phenotype of Crohn's disease.

OBJECTIVE: Very little is known about the impact of Helicobacter pylori (H. pylori) infection on Crohn's disease. In this study we investigated a possible influence of H. pylori on the phenotype of Crohn's disease. METHODS: Patients with Crohn's disease who had gastric biopsy between 1990 and 1994 and a clinical follow-up in our outpatient clinic for at least 2 yr were included in the study. The mean number of flare-ups per year of follow-up, the mean numbers of intestinal resections per year of disease duration, and primary disease location were compared in H. pylori-positive and -negative patients. Various regression models were calculated to test the influence of H. pylori status on these parameters, correcting for smoking habits and disease duration. RESULTS: Of 131 patients, 50 (38.2%) were H. pylori positive and 62 (47.3%) were smokers. Due to a significant interaction between smoking habits and H. pylori infection, regression models were calculated separately for smokers and nonsmokers. Nonsmokers without H. pylori infection had more flare-ups than nonsmokers with H. pylori infection (0.77 [0.57-0.97] vs 0.29 [0.16-0.42]; p < 0.01; mean [95% confidence interval]). In contrast, nonsmokers without H. pylori infection had less intestinal resections than nonsmokers infected with H. pylori (0.08 [0.04-0.12] vs 0.11 [0.07-0.15]; p < 0.05). These differences were not significant for smokers (p < 0.41 and p < 0.07). There was a predominance of small bowel disease in H. pylori-positive patients, which did not reach statistical significance. CONCLUSIONS: Our data indicate that H. pylori influences the phenotype of Crohn's disease, especially in nonsmokers.

Adult↗

PubMed1998

Cytokine and prostaglandin production by amnion cells in response to the addition of different bacteria.

OBJECTIVE: Our goal was to evaluate the effect of Escherichia coli, Bacteroides fragilis, Mycoplasma hominis, and Staphylococcus aureus on cytokine and prostaglandin production by amnion cells in vitro. STUDY DESIGN: Amnion cells were obtained from women undergoing elective cesarean section before the onset of labor and cultured in a primary cell culture. Confluent amnion cells were incubated with heat-inactivated bacteria in different concentrations (10(1) to 10(6) colony-forming units/ml) for 48 hours. Samples for quantification of interleukin-1 beta, interleukin-6, interleukin-8, tumor necrosis factor-alpha, and prostaglandin E2 were collected at 6, 12, 24, and 48 hours. RESULTS: Under basal conditions, minor amounts of interleukin-6 and interleukin-8 were detectable. Incubation of amnion cells with E. coli enhanced the secretion of interleukin-8 and also induced an transient increase of prostaglandin E2 in a dose-dependent manner. B. fragilis produced an increase in the secretion of interleukin-6 and interleukin-8. M. hominis and S. aureus did not cause an increase in either interleukin-6, interleukin-8, or prostaglandin E2. CONCLUSION: The gram-negative bacteria E. coli and B. fragilis stimulated interleukin-6 and interleukin-8 to a greater degree than the other bacteria investigated in this study. This finding may be of clinical interest in the onset of preterm birth.

Amnion↗

PubMed1998

Hyperemesis gravidarum associated with Helicobacter pylori seropositivity.

OBJECTIVE: To test the hypothesis that infection with Helicobacter pylori is associated with hyperemesis gravidarum. METHODS: From January 1995 to November 1996 we enrolled 105 patients with hyperemesis gravidarum in a prospective study. The Helicobacter serum Immunoglobulin (Ig) G concentrations in these patients were compared with those in asymptomatic gravidas matched for week of gestation. RESULTS: Positive serum IgG concentrations were found in 95 of the 105 hyperemesis patients (90.5%) compared with 60 of 129 controls (46.5%). A chi2 test showed statistical significance (P < .001). The mean (+/-standard deviation) index percentages of the IgG titers were 74.2+/-23.6% in the hyperemesis group and 24.3+/-4.4% in the control group (P < .01, Student t test). CONCLUSION: Infection with H pylori may cause hyperemesis gravidarum.

Adolescent↗