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Biomedical subjects

L P Andersen

Publications and source records attributed to L P Andersen.

At least 55 records · Page 3Linked to original sources
PubMed1997

The histopathology of human gastric mucosa inhabited by Helicobacter heilmannii-like (Gastrospirillum hominis) organisms, including the first culturable case.

The aim was to determine the prevalence of Helicobacter heilmannii-like organisms in human gastric biopsies and the associated histology compared with that of Helicobacter pylori-bearing gastric biopsies. Furthermore, the feasibility of culturing H. heilmannii was examined. A consecutive series of 727 gastric biopsies from 650 patients were prospectively scrutinized for H. heilmannii. Their distribution pattern was recorded as well as the affiliated morphology of the gastric mucosa. Additional biopsies from some of the patients were examined microbiologically. Four cases (0.6%)(95% confidence intervals: 0.01-1.2%) of the examined material harboured H. heilmannii. The bacterial burden was graded as sparse in three cases, moderate in one case. The distribution pattern was patchy; thus, in no case did all biopsies from one endoscopy comprise H. heilmannii. Adhesion to epithelial cells was infrequent. A mild gastritis, active in three cases, characterized all biopsies. Lymphoid aggregates occurred in biopsies from three patients. Micropapillary tufting of the epithelial layer and intestinal metaplasia were not apparent. Culture studies proved successful in the one of the four cases assayed. In conclusion the morphology of H. heilmannii-bearing mucosa deviates from that of H. pylori-associated mucosa by the absence of epithelial damage in the former. This observation can in part be explained by the predominant location of H. heilmannii at a distance from the epithelium in contrast to the conspicuous H. pylori adhesion to epithelial cells, coupled with a usually low bacterial burden and patchy occurrence of H. heilmannii as opposed to the generally more heavy infestation with H. pylori.

Adult↗
PubMed1997

Antimicrobial susceptibility testing of 230 Helicobacter pylori strains: importance of medium, inoculum, and incubation time.

No standardized method of susceptibility testing for Helicobacter pylori is currently available, so before a large agar dilution study comprising 230 H. pylori strains belonging to more than 80 genetically different groups was initiated, we performed a relatively small preliminary study to determine the influences of medium, inoculum density, and incubation time. Seven media were investigated and were primarily evaluated on the basis of their abilities to support growth both semiquantitatively and qualitatively; Iso-Sensitest agar supplemented with 10% horse blood was found to be well suited for the purpose; this was closely followed by Mueller-Hinton agar with 10% horse blood, Mueller-Hinton with 10% sheep blood, and finally, 7% lysed horse blood agar. Investigations of two inoculum densities and two incubation times resulted in recommendations for the use of 10(9) CFU/ml (10[6] CFU/spot) as the inoculum and 72 h as the incubation time. A modest inoculum effect was noted for amoxicillin and metronidazole. By the methodology derived from our preliminary study, the susceptibilities of 230 H. pylori strains to six antibiotics were subsequently determined. The results were generally in accord with those of others, and apart from metronidazole, the MIC of which for approximately 25% of the strains tested was >8 microg/ml, resistance was low in Denmark. The situation might, however, quickly change when and if the number of indications for antibiotic therapy for H. pylori infections increase. Consequently, susceptibility testing of all H. pylori strains is recommended in order to survey the development of resistance, and in our hands the described methodology was relatively easy to perform and the results were easy to read.

Animals↗
PubMed1997

Relation between Helicobacter pylori infection and gastrointestinal symptoms and syndromes.

BACKGROUND: Helicobacter pylori is a human pathogen that colonises the gastric mucosa and causes permanent gastric inflammation. AIMS: To assess the symptoms of H pylori infection in an adult unselected population. SUBJECTS: A random sample of 3589 adult Danes who were examined in 1982 and 1987 (n = 2987). METHODS: Abdominal symptoms within the preceding year were recorded at both attendances. Circulating IgG antibodies against H pylori in serum samples drawn in 1982 were measured by using in-house indirect enzyme linked immunosorbent assays (ELISA). RESULTS: People with increased levels of IgG antibodies to H pylori were more likely than uninfected individuals to report heartburn (odds ratio (OR) = 1.26, 95% confidence interval (CI) 1.03-1.54) and abdominal pain characterised by daily length (OR = 1.33, 95% CI 0.92-1.91), nocturnal occurrence (OR = 1.62, 95% CI 1.19-2.19), spring aggravation (OR = 1.68, 95% CI 0.70-4.05), and no relation to meals (OR = 0.62, 95% CI 0.43-0.91) or stress (OR = 0.69, 95% CI 0.50-0.95). The inclusion of people with increased levels of IgG antibodies to H pylori, but without upper dyspepsia, at study entry significantly increased the likelihood of reporting upper dyspepsia at follow up (OR = 1.71, 95% CI 1.24-2.36). People with epigastric pain and increased levels of IgM antibodies to H pylori only indicative of acute H pylori infection were more likely to report nocturnal pain, heartburn, nausea, and vomiting. CONCLUSION: H pylori infection may precede the development of dyspepsia and is associated with a variety of gastrointestinal symptoms in people with no history of peptic ulcer disease.

Abdominal Pain↗
PubMed1996

Seroprevalence of immunoglobulin G, M, and A antibodies to Helicobacter pylori in an unselected Danish population.

The seroprevalences of increased levels of immunoglobulin G (lgG), M (lgM), and A (lgA) antibodies to Helicobacter pylori were assessed by enzyme-linked immunosorbent assay techniques in 3,589 Danes who participated in a population study in Copenhagen County in 1982. A total of 33.9% of the study population had one or more classes of increased antibodies to H. pylori. Increased levels of lgG, lgM, and lgA antibodies to H. pylori were seen in 25.9% (95% confidence interval (Cl) 24.5-27.3), 4.5% (95% Cl 2.2-7.0), and 12.0% (95% Cl 10.9-13.1) of the participants, respectively. Women were significantly more likely than men to be seropositive for lgM antibodies (Mantel-Haenszel summary odds ratio = 1.85, 95% Cl 1.34-2.57). Seropositivity for lgM antibodies to H. pylori was found less often with increasing age. An lgG antibody response was not seen in 23.7% of cases with overall increased antibodies to H. pylori. Increased levels of lgG or lgA antibodies were more frequent in people with a history of peptic ulcer disease. Seroprevalences of increased H. pylori antibodies are high in unselected populations. Primary H. pylori infections are contracted at all ages, but infection rates decline with age. Inclusion of measurements of lgA and lgM antibody levels in future screening for H. pylori may improve the diagnostic sensitivity of serologic analyses.

Adult↗
PubMed1996

Specific neutrophil hyporesponsiveness in chronic Helicobacter pylori infection.

The release from mucosal neutrophils of reactive oxygen species (ROS) is believed to be an important part of the pathogenesis of Helicobacter pylori-associated gastritis and duodenal ulcer. In this study, bacterial sonicates prepared from 1 reference and 29 patient strains were used to stimulate ROS release from peripheral blood neutrophils. In 29 H. pylori-positive patients, the neutrophil response toward the homologous strain was absent. In contrast, a significant response was observed toward the reference strain. In addition, on stimulation of neutrophils from 29 patients without H. pylori infection, ROS release was significant. The stimulatory effect on neutrophils by FMLP was comparable in the 2 groups. It is concluded that a specific neutrophil hyporesponsiveness in ROS release toward the homologous R. pylori strain exists. This feature has, to our knowledge, not been described previously for neutrophil responses to any human pathogen.

Adult↗
PubMed1996

Socioeconomic factors in Helicobacter pylori infection among Danish adults.

OBJECTIVES: This study examined the relationship between housing conditions, educational level, occupational factors, and serologically diagnosed acute and chronic Helicobacter pylori infection. METHODS: Immunoglobulin G and immunoglobulin M serum antibodies against H. pylori were measured in 3589 Danish adults who participated in a population study. RESULTS: Low socioeconomic status (odds ratio [OR] = 2.2, 95% confidence interval [CI] = 1.7, 3.0), short duration of schooling (OR = 2.0, 95% CI = 1.3, 2.5), lack of training/education (OR = 1.4, 95% CI = 1.2, 1.7]), unskilled work (OR = 1.7, 95% CI = 1.2, 2.5), and high work-related energy expenditure (OR = 1.4, 95% CI = 1.1, 1.9) increased the likelihood of chronic H. pylori infection. Infection was frequent in people who had lived abroad. Increased levels solely of immunoglobulin M antibodies were found more often in people who were divorced (OR = 2.3, 95% CI = 1.2, 4.4) or unmarried (OR = 2.0, 95% CI = 1.1, 3.8) or who worked long hours (OR = 2.0, 95% CI = 1.1, 4.0). CONCLUSIONS: Educational and occupational factors relate to the likelihood of chronic H. pylori infection in adults. The rate of acute infection is high in single individuals.

Acute Disease↗
PubMed1995

Investigation of Helicobacter pylori ascorbic acid oxidating activity.

Helicobacter pylori sonicate was shown to oxidize ascorbic acid. Ascorbic acid oxidation was determined by chromatography combined with electrochemical detection. Water soluble ascorbic acid oxidase activity was rather independent of pH with a pH optimum around 2. By gel filtration the oxidizing activity co-eluted with an absorbency peak at 408 nm. The relative molecular mass (Mr) was approximately 14,000. It is suggested that this oxidating activity was caused by a cytochrome c-like molecule. Ascorbic acid oxidating activity could also be extracted from bacterial membranes by detergents. Gel filtration showed several forms, the major one with a Mr = 19,000. pH optimum was 6-7. Other oxidase-positive bacterial strains like Campylobacter coli, Enterobacter cloacae and Pseudomonas aeruginosa could degrade ascorbic acid. Since ascorbic acid oxidation by Helicobacter pylori whole bacterial lysates has a pH optimum in the acidic range corresponding to pH in gastric fluid, the activity of the cytochrome c-like water soluble oxidant of Helicobacter pylori seems to be primarily important for the destruction of ascorbic acid in the gastric juice of infected patients.

Ascorbic Acid↗
PubMed1995

Development of a PCR-based technique for detection of Helicobacter pylori.

A primer-set was designed for specific detection of genes that encode for 16S rRNA of Helicobacter pylori, using direct polymerase chain reaction (PCR). The primers were selected in the hypervariable regions, derived from a complete small subunit 16S rRNA sequence of the reference strain H. pylori CCUG 17874. The primer-set amplified a 537 base pair (bp) sequence specifically from chromosomal H. pylori DNA. Amplification of purified chromosomal H. pylori DNA was achieved at concentrations as low as 1 femto gram (fg), equivalent to 5 bacteria. Furthermore, as few as 1 lysed H. pylori cell was detected by this PCR technique. The specificity of the primers was 100%, since purified chromosomal DNA was detected from all 32 various H. pylori isolates, whereas no other bacteria species were detected, whether related to Helicobacter or not. The 16S rDNA primers successfully detected H. pylori in antral biopsy specimens collected from infected patients.

Adult↗
PubMed1995

Cross-reactive antigens shared by Pseudomonas aeruginosa, Helicobacter pylori, Campylobacter jejuni, and Haemophilus influenzae may cause false-positive titers of antibody to H. pylori.

Cystic fibrosis (CF) patients suffer from many of the gastrointestinal conditions which occur in non-CF individuals, e.g., dyspepsia and peptic ulceration. These symptoms may be caused by Helicobacter pylori but could also be due to either pancreatic insufficiency or the intensive antibiotic treatment used in CF patients. Since CF patients chronically infected with Pseudomonas aeruginosa produce antibodies against a wide range of antigens, including antigens common to many other bacteria, e.g., GroEL and lipopolysaccharide, we studied, by the Western blot (immunoblot) technique, the specificity of immunoglobulin G antibodies to H. pylori in Danish CF patients chronically infected with P. aeruginosa, CF patients without P. aeruginosa infection but with Haemophilus influenzae infection, patients with dyspeptic ulcers associated with H. pylori, and patients recovering from acute Campylobacter jejuni or Campylobacter coli infection. Sera from CF patients with chronic P. aeruginosa or H. influenzae infection and patients recovering from acute C. jejuni infection cross-reacted with H. pylori antigens. A strong cross-reacting protein antigen at approximately 14 kDa and minor cross-reactive antigens at approximately 27, 30, and 60 kDa (the heat shock protein GroEL is equivalent to the common antigen of P. aeruginosa) could be demonstrated. The results of this study show that high immunoglobulin G antibody titers against H. pylori in CF patients cannot be regarded as indicating present or past H. pylori infection unless their specificity is proven by absorption studies.

Antibodies, Bacterial↗
PubMed1995

Isolation and preliminary evaluation of a low-molecular-mass antigen preparation for improved detection of Helicobacter pylori immunoglobulin G antibodies.

Previously, immunoglobulin G (IgG) antibodies to five antigens with a relative molecular mass of between 15 and 30 kDa from Helicobacter pylori were found to be significantly more frequent in H. pylori-infected patients than in noninfected patients. In this study, these specific low-molecular-mass (LMW) antigens were separated by ultrafiltration of whole-cell sonicates. The LMW antigen preparation was evaluated by enzyme-linked immunosorbent assay with serum samples from 76 children with abdominal symptoms and 151 adults with dyspeptic symptoms. H. pylori was cultured or seen in 40 (53%) children and 83 (55%) adults. Increased antibody levels to H. pylori were found in serum from 35 (46%) children and 88 (58%) adults. Values for sensitivity, specificity, and predictive value of positive and negative results of the test were higher with LMW antigens than with the heat-stable antigen previously described. The low specificity and predictive value of a positive result were due to seropositive results for 21 persons with a negative culture for H. pylori and negative microscopy results for Helicobacter-like organisms in biopsies from gastric mucosa. Histologically, chronic gastritis was demonstrated in 43% of these persons, and 19% had peptic ulcer, indicating that they have or have had H. pylori infection. Specific antibodies to H. pylori were confirmed in all 21 patients by the Western immunoblot technique. Use of the LMW antigen improved the IgG antibody detection in patients with H. pylori infection, even though the results reflect the difficulties in establishing a true gold standard for diagnosis of H. pylori infection.

Adolescent↗
PubMed1995

Neutrophil degranulation by Helicobacter pylori proteins.

Mucosal biopsy specimens from patients with Helicobacter pylori infection in gastric antrum contain an increased amount of myeloperoxidase. This study was performed to elucidate the interaction of H pylori sonicate protein(s) and neutrophils concerning myeloperoxidase release. Neutrophil degranulation with myeloperoxidase release was examined in a direct stimulating assay. Priming activity of H pylori was examined after preincubating neutrophils in sonicate, either crude or modified by heat treatment, pronase inactivation and dialysis, and stimulating with N-formyl-methionyl-leucyl-phenylalanine (fMLP) or serum opzonised zymosan (OZ). It was found that H pylori sonicate protein(s) stimulates neutrophil degranulation with myeloperoxidase release in a concentration dependent way. The activity was distinct from fMLP and capable of priming the subsequent fMLP and OZ response. Experiments with the modified bacterial sonicate suggest the activity is caused by a protein, but the findings show that non-protein molecules, for example, lipopolysaccarides were also part of the H pylori sonicate priming activity. The increased mucosal myeloperoxidase in H pylori associated disease can be a direct consequence of bacteria derived stimulation of inflammatory neutrophils.

Bacterial Proteins↗
PubMed1995

Activation of phagocytes by Helicobacter pylori correlates with the clinical presentation of the gastric infection.

Only a minority of subjects with Helicobacter pylori infection develop clinical gastroduodenal disease. It is unclear whether host factors or bacterial virulence properties contribute to the pathogenic mechanisms. We have previously demonstrated a 25-35-kDa protein with phagocyte stimulatory activity in bacterial sonicates. Protein preparations were made from 15 H. neutrophil and monocyte chemotaxis and chemiluminescence was assessed with cells from healthy donors in comparison with N-f-methionyl-leucyl-phenylalanine and C5a anaphylatoxin. The potency of bacterial protein(s) for induction of monocyte chemiluminescence was significantly higher for strains from ulcer patients (1 +/- 1 microgram/ml induced > or = twofold increase of control response) and chronic active gastritis (1 +/- 1 microgram/ml) compared with superficial gastritis (> 1,000 microgram/ml, p<0.05). Neutrophil activation was also significantly more potent with strains from duodenal ulcer disease. The chemotactic activity of bacterial preparations was not significantly different between the groups. We conclude that bacterial strains with pronounced activation of phagocytes are associated with the presence of clinical ulcer disease, supporting the existence of ulcerogenic strains.

Adult↗
PubMed1995

Serodiagnosis of Helicobacter pylori infection in patients with human immunodeficiency virus infection.

In contrast to the established role of Helicobacter pylori gastritis in gastritis and duodenal ulcer in general, conflicting results have been reported in patients with human immunodeficiency virus (HIV) infection and the acquired immunodeficiency syndrome. The seroprevalence during early HIV infection is unknown. We retrospectively studied 102 patients with HIV infection early during the infection and in most cases in asymptomatic patients. Serological IgG antibody response to H. pylori was assessed by ELISA. Compared with an age-matched control group the seroprevalence of H. pylori positivity was not significantly different (19% vs 25%). We observed no association with CD4 counts, p24 antigen, antibiotic prophylaxis with sulfamethoxazole/trimethoprim or antiretroviral treatment. In 54 of 83 patients initially seronegative a second examination was performed after a median of 24 months (range 3-60 months) and 2 patients had H. pylori seroconverted, indicating an incidence of new infection of 2%/year. In conclusion, previous reports have underestimated the prevalence of H. pylori infection in HIV patients, which seems to be similar to that in an HIV-negative population.

Adult↗
PubMed1994

Changing patterns among the subgroups of strains of Staphylococcus aureus of phage group II in Danish hospitals from 1961-91.

During the period 1961-91 a total of 567,635 strains of Staphylococcus aureus from hospitalized patients in Denmark have been characterized according to their antibiotic resistance, site of isolation and phage type. Strains of phage group II (typed by the phages 3A, 3C, 55 and 71) have been analysed further. The occurrence of group II strains was relatively constant (approximately 16%) from 1961 until 1983. Since then the frequency of group II strains increased; in 1991 they accounted for 22.7% of all S. aureus strains isolated. Strains of group II can, on the basis of their phage types, be divided in four subgroups: 3A, 71, 71+ and the 'rest of group II'. Furthermore, within these groups strains may differ from one another in respect to their sensitivity to phages. The increased isolation of group II strains during recent years was because of an increase in strains of subgroups 71+ and the 'rest of group II strains'. In 1991 these two subgroups accounted for 89.7% of all group II strains. Furthermore, an increasing number of group II strains, 71.4% in 1991, was typable only at RTD x 100. The increase in the number of group II strains was even throughout Denmark. All four subgroups of group II have, during the observation period, become more frequently resistant to penicillin and/or tetracycline. Strains typed at 100 x RTD of subgroup 71+ and the 'rest of group II' are more frequently antibiotic resistant than the rest of the group II strains. Strains of the increasing subgroups occurred most often in abscesses.

Abscess↗
PubMed1994

Neutrophil activation by Helicobacter pylori lipopolysaccharides.

Helicobacter pylori-induced release of toxic substances by neutrophils could be of potential importance in the pathogenesis of gastroduodenal inflammatory diseases. Lipopolysaccharide (LPS) has the ability to induce neutrophil activation at very low concentrations. Neutrophil oxidative metabolism and enzyme release were assessed after stimulation of neutrophils with various preparations of LPS from H. pylori and compared with that obtained with Salmonella typhimurium LPS. No direct activation of neutrophils by LPS was observed. Preincubation with LPS showed a significant priming for increased activity on subsequent stimulation, particularly with rough-form LPS. The potency of H. pylori LPS was 10-fold lower than that of S. typhimurium LPS, probably reflecting the unique biochemical structure of H. pylori LPS. Chronic low-grade stimulation by H. pylori LPS in the gastric mucosa may render neutrophils primed for the excessive release of detrimental substances into the tissue on stimulation by other mediators.

Adult↗
PubMed1994

Helicobacter pylori infection in children with recurrent abdominal pain.

Helicobacter pylori was cultured and Helicobacter-like organisms (HLO) were seen in 6 (16%) of 37 children with recurrent abdominal pain. Five children had concomitant histological inflammation, but none had endoscopic changes. All 6 children demonstrated positive serology. Compared with the total group, they were more often from developing countries, larger families and lower social groups. Treatment with phenoxymethyl penicillin and colloidal bismuth subcitrate did not result in side effects or elevated serum levels of serum bismuth. Three children demonstrated metronidazole-resistant strains and the treatment of these children remained an unsolved problem. Among the 31 H. pylori/HLO negative children 8 (26%) demonstrated histological changes, 5 (16%) endoscopic changes and 11 (35%) had positive serology. In conclusion, pathological findings at upper gastrointestinal endoscopy are common in children with recurrent abdominal pain. Because of disconcordance between endoscopy, histology and culture, we recommend that biopsies should always be taken to clarify the diagnosis.

Abdominal Pain↗
PubMed1994

The humoral immune response to Helicobacter pylori infection in children with recurrent abdominal pain.

The systemic humoral immune response to Helicobacter pylori antigens was investigated in 36 children with recurrent abdominal pain (RAP). H. pylori was cultured and Helicobacter-like organisms (HLO) were seen in six children, three of whom had active and two inactive chronic gastritis. None of these children had endoscopic abnormalities. All sex children had increased IgG antibodies to heat-stable H. pylori antigens which were of the IgG1 and IgG3 subclasses. Using six other IgG tests, four of which were commercially available, two to five H. pylori-positive children were found seropositive. Five of six H. pylori-negative children with inactive chronic gastritis and no endoscopic abnormalities had increased IgM antibody levels in addition to increased or borderline increased IgG antibody levels to H. pylori, indicating activity in a chronic H. pylori infection. Five children without H. pylori and with no morphological changes, but with gastritis or duodenitis by endoscopy, had significantly lower IgG and IgA antibody levels compared to other groups. Six of nineteen children without H. pylori, and with no morphological or endoscopic changes had increased IgG and IgM antibody levels to H. pylori. All H. pylori-negative children were seronegative by the four commercial kits. Overall, 12 (33%) of 36 children with RAP were either H. pylori positive by culture and microscopy or had increased IgG antibody levels to H. pylori, which is significantly different from the 10-14% seropositive rate of asymptomatic children. H. pylori may therefore be a cause of RAP in one quarter to one third of the children with RAP in whom other etiologies of RAP are excluded. Further studies on a large number of children are needed for an extended evaluation of the humoral immune response to H. pylori and for further examination of commercial kits which seem to give a high number of false-negative results.

Abdominal Pain↗