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Asa Ljungh

Publications and source records attributed to Asa Ljungh.

At least 19 recordsLinked to original sources
PubMed2006

Lactic acid bacteria as probiotics.

A number of Lactobacillus species, Bifidobacterium sp, Saccharomyces boulardii, and some other microbes have been proposed as and are used as probiotic strains, i.e. live microorganisms as food supplement in order to benefit health. The health claims range from rather vague as regulation of bowel activity and increasing of well-being to more specific, such as exerting antagonistic effect on the gastroenteric pathogens Clostridium difficile, Campylobacter jejuni, Helicobacter pylori and rotavirus, neutralising food mutagens produced in colon, shifting the immune response towards a Th2 response, and thereby alleviating allergic reactions, and lowering serum cholesterol (Tannock, 2002). Unfortunately, most publications are case reports, uncontrolled studies in humans, or reports of animal or in vitro studies. Whether or not the probiotic strains employed shall be of human origin is a matter of debate but this is not a matter of concern, as long as the strains can be shown to survive the transport in the human gastrointestinal (GI) tract and to colonise the human large intestine. This includes survival in the stressful environment of the stomach - acidic pH and bile - with induction of new genes encoding a number of stress proteins. Since the availability of antioxidants decreases rostrally in the GI tract production of antioxidants by colonic bacteria provides a beneficial effect in scavenging free radicals. LAB strains commonly produce antimicrobial substance(s) with activity against the homologous strain, but LAB strains also often produce microbicidal substances with effect against gastric and intestinal pathogens and other microbes, or compete for cell surface and mucin binding sites. This could be the mechanism behind reports that some probiotic strains inhibit or decrease translocation of bacteria from the gut to the liver. A protective effect against cancer development can be ascribed to binding of mutagens by intestinal bacteria, reduction of the enzymes beta-glucuronidase and beta-glucosidase, and deconjugation of bile acids, or merely by enhancing the immune system of the host. The latter has attracted considerable interest, and LAB have been tested in several clinical trials in allergic diseases. Characteristics ascribed to a probiotic strain are in general strain specific, and individual strains have to be tested for each property. Survival of strains during production, packing and storage of a viable cell mass has to be tested and declared.

Antibiosis↗
PubMed2005

Extremely low electrical current generated by porcine small intestine smooth muscle alters bacterial autolysin production.

The effect of extremely low electrical currents, identical to those generated by the gut smooth muscle, on bacterial autolysin production in vitro was tested in the present study. When stimulated with these electrical currents, the bacteria Pediococcus pentosaceus 16:1 produced groups of peptidoglycan hydrolases that differed from those produced by the unstimulated (control) bacteria. The autolysins synthesized by the P. pentosaceus 16:1 under extremely low electrical currents were effective against peptidoglycans from the cell walls of various lactic acid bacteria strains, whereas the autolysins from the control bacteria acted exclusively against P. pentosaceus 16:1 cell walls. Thus, it can be predicted that in vivo the electrical currents generated by the intestinal smooth muscles, which can be recorded as the myoelectrical migrating complexes, could regulate lactic acid bacteria strain growth in the gut.

Animals↗
PubMed2005

Helicobacter pylori and other Helicobacter species in gallbladder and liver of patients with chronic cholecystitis detected by immunological and molecular methods.

OBJECTIVE: Despite several recent reports on the detection of Helicobacter DNA in human bile, there are still uncertainties concerning the correlation of these findings with biliary tract and liver diseases. MATERIAL AND METHODS: Using molecular methods and immunohistochemistry (IHC), we investigated gallbladder and liver biopsy specimens from 22 adult Ukrainian patients with chronic cholecystitis for the presence of Helicobacter species. Patient sera were collected and tested for antibody reactivity to antigens of three Helicobacter spp. Detection of Helicobacter DNA was performed using a Helicobacter genus-specific 16S rDNA PCR. Amplified DNA was identified by PCR-denaturating gradient gel electrophoresis (DGGE) and DNA sequencing. Tissue sections of gallbladder and liver were examined by IHC with antibodies specific to H. pylori, the CagA and VacA cytotoxins of H. pylori, H. hepaticus and to Campylobacter jejuni. Patient sera were analysed by immunoblot for IgG antibodies to soluble surface proteins of H. pylori, H. hepaticus and H. bilis. RESULTS: Helicobacter DNA was found in 16/22 (73%) of the gallbladder samples and in 11/22 (50%) of the liver samples. IHC showed the presence of the H. pylori specific cytotoxins CagA and VacA inside the gallbladder epithelial cells without co-localization of H. pylori at the epithelial lining. Immunoblot analysis of the patient sera did not show any correlation between the presence of Helicobacter DNA and IgG antibody responses. CONCLUSIONS: The high prevalence of Helicobacter DNA and the positive findings by IHC in gallbladder and liver raise questions concerning an infectious role of Helicobacter in patients with chronic cholecystitis.

Adult↗
PubMed2004

Mersacidin eradicates methicillin-resistant Staphylococcus aureus (MRSA) in a mouse rhinitis model.

OBJECTIVES: Methicillin-resistant Staphylococcus aureus (MRSA) often colonize the anterior nares, and nasal carriage remains the main source of bacterial dissemination. The aim of this study was to assess the in vivo activity of the lantibiotic mersacidin against MRSA colonizing nasal epithelia. METHODS: The efficiency of mersacidin in the eradication of MRSA was tested employing mice pre-treated with hydrocortisone and inoculated intranasally either three or six times with a bacterial suspension. RESULTS: In mersacidin-treated animals, pre-colonized with MRSA, bacteria could not be detected in blood, lungs, liver, kidney, spleen or nasal scrapings and there were no lesions manifested after intraperitoneal drug application. Blood samples from infected mice obtained 2 h after mersacidin therapy revealed anti-MRSA activity in a serum bactericidal test. Moreover, elevated interleukin-1beta and tumour necrosis factor-alpha titres were noticed in the pre-infected but not in cured animals. In contrast, mersacidin did not induce differences in the cytokine profiles of treated uninfected control mice. CONCLUSIONS: In the mouse rhinitis model, mersacidin was able to eradicate MRSA colonization. The site of action (epithelium versus blood) of mersacidin needs to be further explored.

Animals↗
PubMed2004

A von Willebrand factor-binding protein from Staphylococcus lugdunensis.

In the present study, a phage display library covering the genome of Staphylococcus lugdunensis, was affinity-selected against von Willebrand factor (vWf). This led to the identification of a gene, vwbl, encoding a putative cell surface protein of 2060 amino acids, denoted vWbl. The deduced protein has an overall organisation typical of staphylococcal cell surface proteins, with an N-terminal signal peptide, and a C-terminal cell wall sorting signal. The vWf-binding part is located in repetitive domains and antibodies against vWbl or vWf can inhibit the binding. Southern blot analysis showed that vwbl was present in the 12 S. lugdunensis strains tested.

Amino Acid Sequence↗
PubMed2004

Effect of the antibacterial activity of pig pancreatic juice on human multiresistant bacteria.

INTRODUCTION: The role of the exocrine pancreas in regulating gut microflora colonization is unclear. The main objective in the current study was to assess the effect of pancreatic fluid on the growth of pathogenic bacteria and fungi. METHODS: The antibacterial activity of pure pig pancreatic juice collected from catheterized, healthy, conscious, and anesthetized pigs was investigated with multiresistant microbial isolates and nonpathogenic strains. Studies were performed on pathogenic bacterial and fungi as well as lactic acid bacteria and reference strains. RESULTS: Pancreatic juice was effective (P < 0.01) against multidrug resistant bacterial pathogens, whereas lactic acid bacteria were insensitive. The antibacterial action was independent of pancreatic juice proteolytic activity. The in vitro antibacterial properties of pancreatic juice last for several hours. Data suggest that broth composition may modulate the intensity of pancreatic juice antibacterial activity. CONCLUSIONS: Pancreatic juice antibacterial activity may be an important factor in limiting the colonization of pathogenic bacteria in the gastrointestinal tract. We postulate that observed antibacterial activity of the pancreatic juice could play an important role as one of the factors of innate immunity.

Animals↗
PubMed2004

Comparative chemical and biological characterization of the lipopolysaccharides of gastric and enterohepatic helicobacters.

BACKGROUND: The lipopolysaccharide of Helicobacter pylori plays an important role in colonization and pathogenicity. The present study sought to compare structural and biological features of lipopolysaccharides from gastric and enterohepatic Helicobacter spp. not previously characterized. MATERIALS AND METHODS: Purified lipopolysaccharides from four gastric Helicobacter spp. (H. pylori, Helicobacter felis, Helicobacter bizzozeronii and Helicobacter mustelae) and four enterohepatic Helicobacter spp. (Helicobacter hepaticus, Helicobacter bilis, 'Helicobacter sp. flexispira' and Helicobacter pullorum) were structurally characterized using electrophoretic, serological and chemical methods. RESULTS: Structural insights into all three moieties of the lipopolysaccharides, i.e. lipid A, core and O-polysaccharide chains, were gained. All species expressed lipopolysaccharides bearing an O-polysaccharide chain, but H. mustelae and H. hepaticus produced truncated semirough lipopolysaccharides. However, in contrast to lipopolysaccharides of H. pylori and H. mustelae, no blood group mimicry was detected in the other Helicobacter spp. examined. Intra-species, but not interspecies, fatty acid profiles of lipopolysaccharides were identical within the genus. Although shared lipopolysaccharide-core epitopes with H. pylori occurred, differing structural characteristics were noted in this lipopolysaccharide region of some Helicobacter spp. The lipopolysaccharides of the gastric helicobacters, H. bizzozeronii and H. mustelae, had relative Limulus amoebocyte lysate activities which clustered around that of H. pylori lipopolysaccharide, whereas H. bilis, 'Helicobacter sp. flexispira' and H. hepaticus formed a cluster with approximately 1000-10,000-fold lower activities. H. pullorum lipopolysaccharide had the highest relative Limulus amoebocyte lysate activity of all the helicobacter lipopolysaccharides (10-fold higher than that of H. pylori lipopolysaccharide), and all the lipopolysaccharides of enterohepatic Helicobacter spp. were capable of inducing nuclear factor-Kappa B(NF-kappaB) activation. CONCLUSIONS: The collective results demonstrate the structural heterogeneity and pathogenic potential of lipopolysaccharides of the Helicobacter genus as a group and these differences in lipopolysaccharides may be indicative of adaptation of the bacteria to different ecological niches.

Antibodies, Bacterial↗
PubMed2004

High prevalence of Helicobacter Species detected in laboratory mouse strains by multiplex PCR-denaturing gradient gel electrophoresis and pyrosequencing.

Rodent models have been developed to study the pathogenesis of diseases caused by Helicobacter pylori, as well as by other gastric and intestinal Helicobacter spp., but some murine enteric Helicobacter spp. cause hepatobiliary and intestinal tract diseases in specific inbred strains of laboratory mice. To identify these murine Helicobacter spp., we developed an assay based on PCR-denaturing gradient gel electrophoresis and pyrosequencing. Nine strains of mice, maintained in four conventional laboratory animal houses, were assessed for Helicobacter sp. carriage. Tissue samples from the liver, stomach, and small intestine, as well as feces and blood, were collected; and all specimens (n = 210) were screened by a Helicobacter genus-specific PCR. Positive samples were identified to the species level by multiplex denaturing gradient gel electrophoresis, pyrosequencing, and a H. ganmani-specific PCR assay. Histologic examination of 30 tissue samples from 18 animals was performed. All mice of eight of the nine strains tested were Helicobacter genus positive; H. bilis, H. hepaticus, H. typhlonius, H. ganmani, H. rodentium, and a Helicobacter sp. flexispira-like organism were identified. Helicobacter DNA was common in fecal (86%) and gastric tissue (55%) specimens, whereas samples of liver tissue (21%), small intestine tissue (17%), and blood (14%) were less commonly positive. Several mouse strains were colonized with more than one Helicobacter spp. Most tissue specimens analyzed showed no signs of inflammation; however, in one strain of mice, hepatitis was diagnosed in livers positive for H. hepaticus, and in another strain, gastric colonization by H. typhlonius was associated with gastritis. The diagnostic setup developed was efficient at identifying most murine Helicobacter spp.

Animals↗
PubMed2003

Carbohydrate recognition by enterohemorrhagic Escherichia coli: characterization of a novel glycosphingolipid from cat small intestine.

A key virulence trait of pathogenic bacteria is the ability to bind to receptors on mucosal cells. Here the potential glycosphingolipid receptors of enterohemorrhagic Escherichia coli were examined by binding of 35S-labeled bacteria to glycosphingolipids on thin-layer chromatograms. Thereby a selective interaction with two nonacid glycosphingolipids of cat small intestinal epithelium was found. The binding-active glycosphingolipids were isolated and, on the basis of mass spectrometry, proton NMR spectroscopy, and degradation studies, identified as Galalpha3Galbeta4Glcbeta1Cer (isoglobotriaosylceramide) and Galalpha3Galalpha3Galbeta4Glcbeta1Cer. The latter glycosphingolipid has not been described before. The interaction was not based on terminal Galalpha3 because the bacteria did not recognize the structurally related glycosphingolipids Galalpha3Galalpha4Galbeta4Glcbeta1Cer and Galalpha3Galbeta4GlcNAcbeta3Galbeta4Glcbeta1Cer (B5 glycosphingolipid). However, further binding assays using reference glycosphingolipids showed that the enterohemorrhagic E. coli also bound to lactosylceramide with phytosphingosine and/or hydroxy fatty acids, suggesting that the minimal structural element recognized is a correctly presented lactosyl unit. Further binding of neolactotetraosylceramide, lactotetraosylceramide, the Le(a)-5 glycosphingolipid, as well as a weak binding to gangliotriaosylceramide and gangliotetraosylceramide, was found in analogy with binding patterns that previously have been described for other bacteria classified as lactosylceramide-binding.

Animals↗
PubMed2003

PCR-denaturing gradient gel electrophoresis and two feces antigen tests for detection of Helicobacter pylori in mice.

PCR-denaturing Gradient Gel Electrophoresis (PCR-DGGE), a method suitable for the detection of microbial species in complex ecosystems, was evaluated for the detection and identification of Helicobacter spp. in feces and stomach tissue of mice. Two commercially available stool antigen tests for clinical diagnostics in humans were also evaluated in the C57Bl/6 mouse model of H. pylori infection. PCR-DGGE detected only Helicobacter ganmani in feces from H. pylori-infected as well as control animals, whereas in stomach specimens it demonstrated the presence of H. pylori in challenged and H. ganmani in control animals. Hence, the method detected DNA only of the predominant Helicobacter spp., which was also shown in cell dilution experiments. The Amplified IDEIA Hp StAR feces antigen test detected H. pylori in feces from all infected animals and generated no false-positive results, whereas the Premier Platinum HpSA-test also detected H. pylori in all infected animals but generated false-positive or equivocal results in 50% of the control animals. Premier Platinum HpSA, as opposed to Hp StAR, cross-reacted with non-pylori Helicobacter spp. in vitro.

Animals↗
PubMed2003

Two-year follow-up of Helicobacter pylori infection in C57BL/6 and Balb/cA mice.

UNLABELLED: Helicobacter pylori infection is associated with chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. We previously found high-grade lymphoma after 13 months' H. pylori infection in C57BL/6 mice. In this study we followed H. pylori infection by three different isolates in C57BL/6 and Balb/cA mice for 23 months. Six-week-old C57BL/6 and Balb/cA mice were infected with H. pylori strains 119p (CagA+, VacA+), SS1 (CagA+, VacA+) and G50 (CagA-, VacA-). Mice were followed at 2 weeks, 10 weeks and 23 months post-inoculation (p.i.) by culture, histopathology and serology. Strain G50 was only reisolated from mice 2 weeks p.i. There was no difference in colonization between strain 119p and SS1 at 10 weeks p.i., whereas SS1 gave 100% colonization versus 119p gave 50% 23 months p.i. Interestingly, the inflammation score was higher in mice infected with strain 119p than with SS1 10-week p.i., and there were lymphoepithelial lesions in mice infected with strain 119p and G50 but not with SS1 at 23 months post-infection. Eight mice infected with strains 119p and G50 developed gastric lymphoma (grade 5 and 4). One C57BL/6 mouse infected with strain 119p developed hepatocellular carcinoma after 23 months. Immunoblot showed specific bands of 26-33 kDa against H. pylori in infected mice, and two mice infected with strain SSI reacted with antibodies to the 120 kDa CagA toxin. CONCLUSION: A reproducible animal model for H. pylori-induced lymphoma and possibly hepatocellular carcinoma is described. Strain diversity may lead to different outcomes of H. pylori infection.

Animals↗
PubMed2003

Enteral crude red kidney bean (Phaseolus vulgaris) lectin--phytohemagglutinin--induces maturational changes in the enterocyte membrane proteins of suckling rats.

This study aimed to investigate the effect of enterally administered crude red kidney bean (Phaseolus vulgaris) lectin, PHA, on the expression of brush-border membrane vesicle (BBMV) proteins, in particular Na(+)/H(+) exchangers (NHEs), in the small intestine of suckling rats. Gavage of PHA to 14-day-old rats for 3 days resulted in altered protein/glycoprotein patterns as analyzed by SDS-PAGE. Immunoblots demonstrated the appearance of two 71- and 27-kD protein bands indicative for NHE3--one of the NHE isoforms--and PHA, respectively. PHA treatment also resulted in an augmented uptake of (22)Na(+) by the BBMV indicating an increase in NHE activity. Overall, the data suggests that enteral PHA exposure may induce maturational changes in enterocyte membrane proteins in young rats. In view of these findings, an investigation into the addition of PHA to infant formulas and weaning diets is warranted.

Animals↗
PubMed2002

Lactotetraosylceramide, a novel glycosphingolipid receptor for Helicobacter pylori, present in human gastric epithelium.

The binding of Helicobacter pylori to glycosphingolipids was examined by binding of (35)S-labeled bacteria to glycosphingolipids on thin-layer chromatograms. In addition to previously reported binding specificities, a selective binding to a non-acid tetraglycosylceramide of human meconium was found. This H. pylori binding glycosphingolipid was isolated and, on the basis of mass spectrometry, proton NMR spectroscopy, and degradation studies, were identified as Galbeta3GlcNAcbeta3Galbeta4Glcbeta1Cer (lactotetraosylceramide). When using non-acid glycosphingolipid preparations from human gastric epithelial cells, an identical binding of H. pylori to the tetraglycosylceramide interval was obtained in one of seven samples. Evidence for the presence of lactotetraosylceramide in the binding-active interval was obtained by proton NMR spectroscopy of intact glycosphingolipids and by gas chromatography-electron ionization mass spectrometry of permethylated tetrasaccharides obtained by ceramide glycanase hydrolysis. The lactotetraosylceramide binding property was detected in 65 of 74 H. pylori isolates (88%). Binding of H. pylori to lactotetraosylceramide on thin-layer chromatograms was inhibited by preincubation with lactotetraose but not with lactose. Removal of the terminal galactose of lactotetraosylceramide by galactosidase hydrolysis abolished the binding as did hydrazinolysis of the acetamido group of the N-acetylglucosamine. Therefore, Galbeta3GlcNAc is an essential part of the binding epitope.

Chromatography, Gas↗
PubMed2002

Immunogenic proteins of Helicobacter pullorum, Helicobacter bilis and Helicobacter hepaticus identified by two-dimensional gel electrophoresis and immunoblotting.

The ecological niches occupied by various species of Helicobacter are not yet known and the full spectrum of diseases associated with Helicobacter infections are not yet defined. Since these fastidious microaerofilic bacteria require special growth conditions new and improved molecular and serologic diagnostic methods have been developed to increase our understanding of their pathogenesis and virulence characteristics. Immunogenic cell surface proteins of Helicobacter pullorum, Helicobacter bilis, and Helicobacter hepaticus were characterised by proteomic techniques using two-dimensional electrophoresis and immunoblotting with antisera from immunised rabbits. Cross-reactivity between the three Helicobacter species were analysed after a four-step cross-absorption experiment. For H. pullorum, H. bilis and H. hepaticus 21, 13 and 27 specific immunogenic proteins, respectively, were identified. These proteins could be of important sero-diagnostic value for analyses of sera from humans, laboratory animals and for the veterinarian field.

Antigens, Bacterial↗
PubMed2002

The role of microorganisms in biliary tract disease.

The biliary tract is normally sterile, but bile-tolerant bacteria are frequently isolated from patients with cholecystitis. Since the identification of about 25 Helicobacter species, some of which may grow in bile, studies have addressed the role of these organisms in primary biliary cirrhosis, primary sclerosing cholangitis, and cholelithiasis. Most of these bacteria show the presence of Helicobacter DNA or antigens in the bile tract and in liver samples. Altogether, data from studies on biliary and hepatic diseases, as well as pancreatic disorders, suggest that bile-tolerant Helicobacter species may induce a chronic infection with possible malignant transformation.

Animals↗
PubMed2002

Venous shear stress enhances platelet mediated staphylococcal adhesion to artificial and damaged biological surfaces.

We investigated the role of blood components in the adhesion of staphylococci to biological and artificial surfaces under well-defined flow conditions by using the Cone and Plate(let) Analyzer. An enzyme-linked immunosorbent assay-like binding assay with biotinylated bacteria determined the extent of bacterial adhesion to subendothelial extracellular matrix (ECM), polystyrene (PS) and adult bovine aortic endothelial (ABAE) cell monolayer. The presence of adsorbed plasma proteins on PS and ECM did not increase and in some cases reduced staphylococcal adhesion under flow conditions (200s(-1)). However, their presence on ABAE cells increased bacterial adhesion but to a level still lower than the adhesion to PS and ECM. In contrast, adhered platelets significantly increased staphylococcal adhesion to both PS and ECM, but did not affect the adhesion to ABAE cells. Furthermore, bacterial adhesion to the platelets coated ECM and PS under flow conditions (200s(-1)) was increased by 1.4 to 2.6-fold compare to static conditions. The platelet-enhanced bacterial adhesion was markedly inhibited by blockade of the platelet GPIb receptor. In conclusion, staphylococcal extensive adhesion to ECM and PS surfaces is increased by venous flow and mediated by surface adhered activated platelets via a GPIb dependent mechanism. On the other hand, ABAE cells demonstrated limited bacterial adhesion that is mediated by adsorbed plasma proteins. Our results suggest that under physiological venous flow conditions the intact vessel wall is less prone for bacterial adhesion than damaged vessel wall.

Animals↗
PubMed2002

Lectin-like binding and antibiotic sensitivity of enterococci from wild herbivores.

Fifty eight enterococcal isolates from wild herbivores were tested for their antibiotic sensitivity pattern and lectin-like binding of extracellular matrix (ECM) and serum proteins. Kanamycin resistance was very frequent; many multiresistant strains were also isolated. All isolates were sensitive to rifampicin. Resistance to gentamicin, novobiocin, and tetracycline was widely distributed in the microflora of wild herbivores breeded in zoological garden in Kosice. No autoaggregating strains were detected among these 58 enterococcal isolates. Various degrees of binding of mucins, fetuin, heparin, fibrinogen, and fibronectin were observed in individual strains. However, bovine lactoferrin binding by enterococci from deers and chamoises was either negative (0) or strongly positive (3). With regard to influence of growth media, TH agar was found to be better for the expression of lectin-like binding than blood agar, TH broth and Nutrient broth. A significant effect (P < 0.001 or P < 0.05) of proteolytic treatment was observed in six selected strains. However, there is a difference between the effect of trypsin and pronase P. Pronase treatment more effectively decreased binding of some strains (1H, 6A, EF 1111, EC 1292), while trypsin treatment decreased more binding of other enterococcal strains (EF 953 and 1E). Significant (P < 0.001) influence of metaperiodate, which cleaves the C-C bond between vicinal groups of sugars, on collagen I binding by three selected strains (1E, 1H, 6A) and bovine lactoferrin binding (by EF 1111, EC 1292, EF 953) was also observed. However, its influence was very different. In two strains (1H and EC 1292), ECM binding was decreased, while in four other strains (1E, 6A, EF 1111, EF 953) it was increased.

Animals↗