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Biomedical subjects

L Engstrand

Publications and source records attributed to L Engstrand.

At least 91 records · Page 5Linked to original sources
PubMed1995

Retrograde transmission of Proteus mirabilis during platelet transfusion and the use of arbitrarily primed polymerase chain reaction for bacteria typing in suspected cases of transfusion transmission of infection.

BACKGROUND: When bacteria are found, after a platelet transfusion, in the recipient's blood as well as in the platelet concentrate (PC), a causal relationship is normally suspected, with the PC as the causative agent. The other alternative, that the patient has bacteremia and contaminated the PC, is less well documented in the literature. CASE REPORT: Arbitrarily primed polymerase chain reaction (AP-PCR) was used for testing strains of Proteus mirabilis isolated from a patient's blood before and after a platelet transfusion and from the PC. Because of a febrile reaction after a platelet transfusion, bacterial culture was performed on the PC used, showing growth of P. mirabilis. The same species was found in the patient's blood after the transfusion. Posttransfusion sepsis caused by a contaminated PC was suspected, and anti-sepsis treatment was given to the recipient. Later, it became apparent that the patient had had bacteremia before the transfusion and that P. mirabilis was one of the species in the isolate. With AP-PCR, the identity of the three P. mirabilis isolates could be distinguished. CONCLUSION: AP-PCR is a useful technique for distinguishing the identity of bacterial isolates from patients and blood components. A patient with bacteremia can contaminate a PC in conjunction with a platelet transfusion. With AP-PCR, the PC could be ruled out as the cause of the posttransfusion sepsis.

Base Sequence↗
PubMed1995

Potential animal models of Helicobacter pylori infection in immunological and vaccine research.

Presence of Helicobacter pylori in the human gastric mucosa is associated with chronic gastritis and promotes the formation of peptic ulceration. Furthermore, long-term gastritis caused by the bacteria represents an increased risk of developing gastric cancer. Much controversy remains about the pathogenic mechanisms by which H. pylori can induce disease because of the limitations of animal models and the relevance of in vitro observations to the in vivo disease process. Studies of putative pathogenic factors such as induction of inflammatory mediators and immune evasion are required to understand how to design a vaccine against the infection. Vaccine adjuvants, delivery systems and therapeutic vaccination are likely to be the areas of major progress in the future. Data related to immunological aspects and vaccine development in potential animal models are reviewed.

Animals↗
PubMed1995

Nucleotide sequence analysis and seroreactivities of the 65K heat shock protein from Mycobacterium paratuberculosis.

Mycobacterium paratuberculosis is the causative agent of Johne's disease, a chronic enteritis in ruminants. It has also been implicated as a possible cause of Crohn's disease, an inflammatory bowel disease of unknown etiology. The mycobacterial 65K heat shock proteins (hsp-65K) are among the most extensively studied mycobacterial proteins, and their immunogenic characteristics have been suggested to be the basis for autoimmunization in chronic inflammatory diseases. In this context, we isolated and sequenced the hsp-65K-encoding gene from our M. paratuberculosis PTB65K genomic library. A high degree of identity was found between the open reading frame (ORF) of the PTB65K gene and those of Mycobacterium tuberculosis (89.6%), Mycobacterium leprae (86.6%), and Mycobacterium avium 18 (98.8%). The amino acid sequence alignment of the PTB65K protein with the hsp-65K homologs revealed that the M. tuberculosis and M. leprae proteins each differed by 36 amino acid residues and that the M. avium 18 protein differed by 8 residues. We also investigated the humoral immune responses of animals with Johne's disease and patients with Crohn's disease against the recombinant PTB65K antigen. Immunoblot analysis showed that sera from only 3 of 10 clinically ill and 5 of 25 subclinically ill cows reacted with PTB65K. In addition, sera from two of two sheep and one of two goats with clinical symptoms of Johne's disease also reacted with PTB65K; 0 samples from 10 normal cows reacted. In humans, sera from 7 of 13 patients with Crohn's disease, 3 of 4 with tuberculosis, 5 of 6 with leprosy, 5 of 12 with non-inflammatory bowel disease, and 0 of 4 with ulcerative colitis reacted with the recombinant PTB65K antigen. These results indicate that this PTB65K heat shock protein is uninformative when used for serodiagnosis of Johne's disease in animals. However, in humans, the high intensity of antibody reactions of some sera from Crohn's disease patients compared with that from noninflammatory bowel disease patients showed a positive correlation with mycobacterial diseases.

Animals↗
PubMed1995

Immunomagnetic separation and PCR for detection of Helicobacter pylori in water and stool specimens.

The detection of Helicobacter pylori in clinical and environmental samples by PCR sometimes requires removal of polymerase inhibitors. We have used a magnetic immunoseparation technique as pre-PCR treatment to facilitate direct detection of H. pylori in stool and water specimens. Rabbit hyperimmune antiserum was produced and magnetic beads were coated with purified immunoglobulin G, which reacted with and bound to both coccoid and rod-shaped forms of H. pylori. When PCR was applied for the detection of H. pylori from cultured samples, the number of organisms that was required for positive scores varied significantly. For a 3-day culture of H. pylori, samples containing 10(2) bacteria per ml are needed for a positive score; for a 6-day culture, samples containing 10(4) bacteria per ml are needed; and for a 10-day culture, samples containing 10(6) bacteria per ml are needed. These results indicate that the coccoid forms of H. pylori may have a different antigenicity and DNA content and are therefore more difficult to detect by immunomagnetic separation and PCR than the rod-shaped forms. Spiked samples with the addition of feces, spiked water samples, and a patient stool specimen were all scored positive with this technique.

Animals↗
PubMed1995

Intracellular penetration and survival of Streptococcus pyogenes in respiratory epithelial cells in vitro.

Recurrence of pharyngotonsillitis caused by S. pyogenes after seemingly adequate antibiotic treatment has puzzled scientists for many years. We investigated the ability of S. pyogenes to invade HEp-2 cells and survive intracellularly. Five strains were tested, of which two were isolated from patients with recurrent pharyngotonsillitis, two without recurrent infection, while one was a reference strain. All five strains were found capable of penetrating the cells and surviving intracellularly for between 4 and 7 days. In this manner, an intracellular reservoir of bacteria was created, with the potential to cause recurrent infections.

Cells, Cultured↗
PubMed1995

Helicobacter pylori seropositivity among Swedish adults with and without abdominal symptoms. A population-based epidemiologic study.

BACKGROUND: The role of Helicobacter pylori in functional dyspepsia is unclear. The aim of this population-based study was to determine whether the prevalence of H. pylori infection is higher among people with dyspepsia or irritable bowel syndrome (IBS) than among symptomless persons after control for age, sex, and socioeconomic status. METHODS: In a postal questionnaire we asked a representative sample (20-79 years; n = 1260) from a Swedish municipality about abdominal symptoms in the preceding 3 months. A randomly selected subsample, 50 with dyspepsia, 50 with IBS, and 50 symptomless, matched with regard to age, sex, and education, were tested for the presence of IgG antibodies to H. pylori, using the HM-CAP immunoassay. RESULTS: Fifty-five persons (38%) were H. pylori-seropositive. The seroprevalence among dyspeptics (33%) did not exceed that in healthy people (48%) or in those reporting IBS (33%). The prevalence increased with age and with lower social class, but the latter association disappeared when age was taken into account. Neither sex nor symptom intensity predicted Helicobacter seropositivity. CONCLUSION: Our data are incompatible with an important aetiologic role for H. pylori in functional dyspepsia.

Age Distribution↗
PubMed1995

DNA fingerprinting of Streptococcus pyogenes from patients with recurrent pharyngotonsillitis by means of random amplified Polymorphic DNA analysis.

In recent years, several DNA fingerprinting methods have been tried for the epidemiological investigation of Streptococcus pyogenes isolates. We chose the Random Amplified Polymorphic DNA (RAPD) method for the typing of pre- and post-antibiotic treatment S. pyogenes isolates obtained from 14 patients with pharyngotonsillitis. Isolates from 4 patients had been collected 10 years earlier than from the others. Hence epidemiological connections between the strains were unlikely. Both pre- and post-antibiotic treatment isolates showed identical RAPD patterns, indicating that recurrences in these patients had been caused by homologous strains of S. pyogenes. It was possible by means of RAPD to differentiate between 12 different T-types and occasionally between clones of the same serotype of S. pyogenes. The RAPD method is an easier alternative to traditional DNA-typing techniques and provides quick results with minimal technical complexity.

Bacterial Typing Techniques↗
PubMed1995

Mycobacterium paratuberculosis and Crohn's disease.

Mycobacterium paratuberculosis is the causative agent of Johne's disease, a chronic enteritis in ruminants. It has been suggested that Crohn's disease, a gastrointestinal disease in humans with similar clinical symptoms and histopathological findings, is caused by the same bacteria. Epidemiological data support Crohn's disease possibly being caused by an infectious agent. Recently, with improved culture techniques and the advent of polymerase chain reaction, M. paratuberculosis has been identified from tissues of increasing numbers of patients with Crohn's disease. However, conflicting data still occur and the case for M. paratuberculosis as the etiological agent of Crohn's disease can be neither proved nor disproved. The development of new diagnostic tests and comprehensive well-defined clinical studies will hopefully provide us with information about this association in the future.

Antibodies, Bacterial↗
PubMed1994

Helicobacter pylori infection: genetic and environmental influences. A study of twins.

OBJECTIVE: To investigate the importance of genetic effects for acquiring Helicobacter pylori infection. DESIGN: Cross-sectional study on monozygotic and dizygotic twins, reared apart and reared together. SETTING: Twins from a subregistry of the Swedish Twin Registry, which includes entries for about 25,000 twin pairs who were born in Sweden. MEASUREMENTS: Helicobacter pylori status was assessed as the presence of anti-H. pylori IgG in 269 pairs of twins, including 36 monozygotic twin pairs reared apart, 64 monozygotic twin pairs reared together, 88 dizygotic twin pairs reared apart, and 81 dizygotic twin pairs reared together. RESULTS: The probandwise concordance rate for H. pylori infection was higher in monozygotic twin pairs (81%) than in dizygotic twin pairs (63%) (P = 0.001). Probandwise concordance rates for H. pylori infection among 124 pairs of twins reared apart were 82% and 66% for monozygotic and dizygotic twins, respectively (P = 0.003). The correlation coefficient was 0.66 for monozygotic twins reared apart, and it provides the best single estimate of the relative importance of genetic effects (heritability) for variation in the acquisition of H. pylori infection. The heritability estimate from model-fitting analyses was 0.57, a similar result. The remaining variance was accounted for by shared rearing environmental (20%) and nonshared environmental factors (23%). The latter contribute to differences, not similarities, among family members. CONCLUSION: This twin study showed that genetic effects influence the acquisition of H. pylori infection because of greater similarities within the monozygotic twin pairs. Further, sharing the same rearing environment also contributes to the familial tendency for acquiring H. pylori infection.

Chi-Square Distribution↗
PubMed1994

Identification and characterization of Mycobacterium paratuberculosis recombinant proteins expressed in E. coli.

Mycobacterium paratuberculosis is the causative agent of Johne's disease, a chronic enteritis in ruminants, and it has also been isolated and identified from patients with Crohn's disease, an inflammatory bowel disease. The control of Johne's disease has been hampered by the lack of a reliable diagnostic test because of the large degree of antigenic cross-reactivity between mycobacterial and non-mycobacterial species. To help identify specific antigen(s) or epitope(s), an M. paratuberculosis expression library was screened with antibodies and DNA probes. In total, 54 clones were randomly picked, purified, and characterized by DNA probes and monoclonal antibodies with known specificity to individual mycobacterial antigens. Four clones carrying the heat shock protein 65K-, two representing the secreted protein 32K-, three representing the 21K-, and 20 clones representing the specific insertion element of M. paratuberculosis (IS900)-encoding genes and their gene products were identified and characterized. Well-defined recombinant antigens and/or epitopes representing M. paratuberculosis may facilitate the development of specific diagnostic tests and the investigation of their role in these chronic diseases.

Antibodies, Monoclonal↗
PubMed1993

Helicobacter pylori infection: independent risk indicator of gastric adenocarcinoma.

BACKGROUND: Helicobacter pylori has been implicated as a possible etiologic factor in gastric cancer. This case control study was performed to determine the association between H. pylori and gastric cancer, taking into account the possibility of confounding by other background factors. METHODS: Sera were collected from 112 incident case patients with gastric cancer and 103 control patients with nongastroenterological diseases, who were frequency-matched with respect to age and sex. Immunoglobulin G antibodies to H. pylori were identified using the HM-CAP immunoassay (Enteric Products Inc., Wesbury, NY). RESULTS: The prevalence of H. pylori seropositivity was significantly higher (P = 0.002) among case patients than control patients. The odds ratio (OR) was 2.60 (95% confidence interval, 1.35-5.02). The increased OR associated with H. pylori infection was confined to tumors with a noncardia location (OR, 3.06) and men (OR, 4.27). OR increased with decreasing age at cancer diagnosis to reach 9.33 in patients < 60 years of age. Multivariate logistic regression analysis was used as control for potential confounding, but the elevated OR associated with H. pylori infection remained significantly increased. CONCLUSIONS: The results support the hypothesis of H. pylori infection as an independent risk indicator of gastric cancer.

Adenocarcinoma↗
PubMed1993

Detection of Helicobacter pylori in dental plaque by reverse transcription-polymerase chain reaction.

To investigate whether the oral cavity is a potential reservoir and possible sanctuary for Helicobacter pylori, supragingival and subgingival plaques were analyzed by a Helicobacter genus-specific reverse transcriptase-polymerase chain reaction based on the sequence data of H. pylori 16S rRNA. The amplified 500-bp DNA fragment was identified by ethidium bromide staining after agarose gel electrophoresis and by Southern hybridization. Twenty-five dyspeptic patients were studied. Histologic examination of gastric biopsy specimens revealed that 18 had H. pylori gastritis and 7 did not. For seven of the 18 (38.8%) patients with proven H. pylori gastritis, H. pylori was also identified in their dental plaque. None of the patients without H. pylori gastritis had H. pylori in their dental plaque. The detection of H. pylori in dental plaque suggests that this H. pylori colonization is not restricted to the gastric mucosa and that this ecological niche may serve as a possible sanctuary which may be responsible for reinoculation of the stomach after topical anti-H. pylori therapies such as bismuth.

Adult↗
PubMed1993

Local and systemic immune response in Helicobacter pylori-associated chronic gastritis before and after treatment.

Ten patients with Helicobacter pylori-associated chronic gastritis were given combination therapy for 6 weeks with a bismuth subnitrate-containing compound and bacampicillin. The eradication rate was 40% 6 weeks after the end of treatment. Two patients remained H. pylori-negative at long-term follow-up after 6 and 17 months; that is, H. pylori was only eradicated in 20% of the patients after long-term observation. By dot blot and immunoblotting both urease and an urease-associated heat shock protein (HSP62) were found to be specific and constant immunodominant H. pylori antigens. The immunohistologic pattern showed induced expression of HLA-DR and HSP62, but not of ICAM-1, in all but two biopsy specimens of gastric epithelial cells. This study suggests i) that long-term observation is important when evaluating the efficacy of anti-H. pylori therapy; ii) that the immune defense mechanisms in the gastric mucosa differ from those in inflammatory conditions affecting other organs, where ICAM-1 and HLA-DR seem to be governed by a common regulator; and iii) that the immunopathologic effects of H. pylori may be caused by autologous and/or bacterial HSPs, which act as triggering factors in the development and persistence of the chronic inflammation in the gastric mucosa.

Adult↗
PubMed1992

Topographic mapping of Helicobacter pylori colonization in long-term-infected pigs.

Four barrier-born pigs were inoculated with Helicobacter pylori during gastroscopy. Infection in all pigs was established after 3 weeks, and the animals were kept isolated from other pigs in ordinary experimental sites. The pigs were sacrificed and examined 3, 5, 6, and 6.5 months postinoculation. A detailed urease mapping of the pig stomachs showed a patchy distribution of H. pylori. The bacteria colonized in all pigs, with a concentration of H. pylori-positive areas in the antrum and fundus. Furthermore, the number of colonized areas tended to increase with time, and some of these areas showed a strong urease reaction, indicating a heavy colonization with H. pylori. Biopsies from these areas contained 10(2) to 10(5) CFU per 2-mm-wide biopsy. We conclude that persistence of H. pylori infection in barrier-born pigs can be demonstrated for at least 6.5 months. The patchy distribution and the variability of viable bacteria were similar to those described for humans.

Animals↗