Biomedical subjects

Mette Boye

Publications and source records attributed to Mette Boye.

12 recordsLinked to original sources

PubMed2006

Identification of a novel, invasive, not-yet-cultivated Treponema sp. in the large intestine of pigs by PCR amplification of the 16S rRNA gene.

Laser capture microdissection in combination with fluorescent in situ hybridization was used to identify an unknown species of spirochetes from the pig colonic mucosa. The 16S rRNA gene was PCR amplified, and the closest related type strain was Treponema bryantiiT (90.1%). The spirochete, here named "Candidatus Treponema suis," was associated with colitis, including invasion of the surface epithelium as well as superficial parts of the mucosa.

Animals↗

PubMed2006

Fusobacterium necrophorum determined as abortifacient in sheep by laser capture microdissection and fluorescence in situ hybridization.

Fluorescent in situ hybridization (FISH) has been extensively used for identification of individual microbial cells within their natural environment. The present work describes the identification of Fusobacterium necrophorum in formalin-fixed tissue samples from three sets of ovine twins aborted at late pregnancy by a technique that combines laser capture microdissection (LCM) and fluorescent in situ hybridization (LCM-FISH). Cultural bacteriological examination had failed to identify an infectious agent but by histological examination, large colonies of bacteria associated with tissue inflammation were seen. In situ hybridization visualized the bacteria in the tissue samples and micro-colonies closely associated with lesions were isolated by LCM. PCR-amplification and sequencing of 16S rRNA gene from the microdissected bacteria identified the organisms as Fusobacterium necrophorum. A rRNA-targeting oligonucleotide probe specific for F. necrophorum was used in a FISH assay. In situ hybridization showed a high density of F. necrophorum in all examined tissue sections. Simultaneous probing with a general bacterial probe EUB338 and the specific probe for F. necrophorum showed that no other bacteria could be detected in the tissue sections. We therefore conclude that F. necrophorum was the likely cause of abortion in these sheep.

Abortion, Spontaneous↗

PubMed2006

Diet- and colonization-dependent intestinal dysfunction predisposes to necrotizing enterocolitis in preterm pigs.

BACKGROUND & AIMS: Preterm birth and formula feeding are key risk factors associated with necrotizing enterocolitis (NEC) in infants, but little is known about intestinal conditions that predispose to disease. Thus, structural, functional, and microbiologic indices were used to investigate the etiology of spontaneous NEC development in preterm pigs. METHODS: Piglets were delivered by cesarean section at 92% gestation, reared in infant incubators, and fed infant formula or colostrum every 3 hours (n = 120) until tissue collection at 1-2 days of age. RESULTS: Clinical and histopathologic signs of NEC were observed in 57% of pigs fed FORMULA (26/46) and in 5% of pigs fed COLOSTRUM (2/38) (P < .05). Relative to COLOSTRUM, both healthy and sick FORMULA pigs had reduced intestinal villous heights, enzyme activities, nutrient absorption, and antioxidant levels and higher inducible nitric oxide synthetase activity (P < .05). In healthy pigs, mucosal microbial diversity remained low and diet independent. NEC pigs showed bacterial overgrowth, and a high mucosal density of Clostridium perfringens was detected in some but not all pigs. Germ-free conditions and antiserum against Clostridium perfringens toxin prevented intestinal dysfunction and NEC in formula-fed pigs, whereas the gut trophic factors, epidermal growth factor, and glucagon-like peptide 2 had limited effects. CONCLUSIONS: A subclinical, formula-induced mucosal atrophy and dysfunction predispose to NEC and bacterial overgrowth. The adverse feeding effects are colonization dependent and may be reduced by factors in colostrum that include antibodies against aggressive toxins such as those of Clostridium perfringens.

Animals↗

PubMed2006

Veterinary and medical aspects of abortion in Danish sheep.

The Danish sheep population totals around 144,000 animals, but little is known of the causes and prevalance of diseases. This study focuses on the causes of abortion in Danish sheep. During one breeding season, aborted foetuses and stillbirths with signs of intrauterine death or malformation were submitted for laboratory examination from a population of 3,758 breeding ewes. Samples from 24 incidents of abortion and 21 ewes delivering malformed lambs or lambs with ante partum decomposition were submitted. A specific aetiology was established in 66.7% and 14.3% of the cases, respectively. Bacterial pathogens were the most prevalent cause of abortion. Several of the abortifacients were zoonotic microorganisms, for example Listeria monocytogenes, Campylobacter fetus subsp. fetus, Yersinia pseudotuberculosis and Toxoplasma gondii. The identified microorganisms probably represent the most common causes of abortion in Danish sheep but occurrence in Denmark of other pathogens such as Coxiella burnetii and Chlamydophila abortus cannot be excluded. Due to the high prevalence of zoonotic microorganisms, precautions must be taken in handling abortions or assisting lambing, especially for pregnant women.

Aborted Fetus↗

PubMed2006

Differential expression of proteins and genes in the lag phase of Lactococcus lactis subsp. lactis grown in synthetic medium and reconstituted skim milk.

We investigated protein and gene expression in the lag phase of Lactococcus lactis subsp. lactis CNRZ 157 and compared it to the exponential and stationary phases. By means of two-dimensional polyacrylamide gel electrophoresis, 28 highly expressed lag-phase proteins, implicated in nucleotide metabolism, glycolysis, stress response, translation, transcription, cell division, amino acid metabolism, and coenzyme synthesis, were identified. Among the identified proteins, >2-fold induction and down-regulation in the lag phase were determined for 12 proteins in respect to the exponential phase and for 18 proteins in respect to the stationary phase. Transcriptional changes of the lag-phase proteins in L. lactis were studied by oligonucleotide microarrays. Good correlation between protein and gene expression studies was demonstrated for several differentially expressed proteins, including nucleotide biosynthetic enzymes, adenylosuccinate synthase (PurA), IMP dehydrogenase (GuaB), and aspartate carbamoyl transferase (PyrB); heat-shock protein DnaK; serine hydroxymethyl transferase (GlyA); carbon catabolite control protein (CcpA); elongation factor G (FusA); and cell division protein (FtsZ).

Animals↗

PubMed2006

Freezing at -800 degrees C distorts the DNA composition of bacterial communities in intestinal samples.

Terminal-restriction fragment length polymorphism (T-RFLP) was used to evaluate how to store intestinal specimens for bacterial community analysis. Bacterial communities are increasingly often described by means of DNA-based methods and it is common practice to store intestinal or faecal specimens either at -20 degrees C or -80 degrees C. In this study, samples of intestines from five different pigs were stored at -80 degrees C and -20 degrees C, respectively and a thawing and freezing procedure was carried out three times for each intestinal per pig per temperature. The cumulative sum of the T-RFLP peak heights (T-RF intensities) decreased as the temperature decreased. The composition of the bacterial community changed when stored at -80 degrees C compared to the samples stored at -20 degrees C. Thus it is recommended from this study that samples of intestinal content are stored at -20 degrees C before use for bacterial community analysis, instead of the current practice at -80 degrees C.

Animals↗

PubMed2005

Pulmonary infections in swine induce altered porcine surfactant protein D expression and localization to dendritic cells in bronchial-associated lymphoid tissue.

Surfactant protein D (SP-D) is a pattern-recognition molecule of the innate immune system that recognizes various microbial surface-specific carbohydrate and lipid patterns. In vitro data has suggested that this binding may lead to increased microbial association with macrophages and dendritic cells. The aim of the present in vivo study was to study the expression of porcine SP-D (pSP-D) in the lung during different pulmonary bacterial infections, and the effect of the routes of infection on this expression was elucidated. Furthermore, the aim was to study the in vivo spatial relationship among pSP-D, pathogens, phagocytic cells and dendritic cells. Lung tissue was collected from experimental and natural bronchopneumonias caused by Actinobacillus pleuropneumoniae or Staphylococcus aureus, and from embolic and diffuse interstitial pneumonia, caused by Staph. aureus or Arcanobacterium pyogenes and Streptococcus suis serotype 2, respectively. By comparing normal and diseased lung tissue from the same lungs, increased diffuse pSP-D immunoreactivity was seen in the surfactant in both acute and chronic bronchopneumonias, while such increased expression of pSP-D was generally not present in the interstitial pneumonias. Co-localization of pSP-D, alveolar macrophages and bacteria was demonstrated, and pSP-D showed a patchy distribution on the membranes of alveolar macrophages. SP-D immunoreactivity was intracellular in dendritic cells. The dendritic cells were identified by their morphology, the absence of macrophage marker immunoreactivity and the presence of dendritic cell marker immunoreactivity. Increased expression of pSP-D in the surfactant coincided with presence of pSP-D-positive dendritic cells in bronchus-associated lymphoid tissue (BALT), indicating a possible transport of pSP-D through the specialized M cells overlying (BALT). In conclusion, we have shown that pSP-D expression in the lung surfactant is induced by bacterial infection by an aerogenous route rather than by a haematogenous route, and that the protein interacts specifically with alveolar macrophages and with dendritic cells in microbial-induced BALT. The function of the interaction between pSP-D and dendritic cells in BALT remain unclear, but pSP-D could represent a link between the innate and adaptive immune system, facilitating the bacterial antigen presentation by dendritic cells in BALT.

Actinobacillus Infections↗

PubMed2005

Laser capture microdissection of bacterial cells targeted by fluorescence in situ hybridization.

Direct cultivation-independent sequence retrieval of unidentified bacteria from histological tissue sections has been limited by the difficulty of selectively isolating specific bacteria from a complex environment. Here, a new DNA isolation approach is presented for prokaryotic cells. By this method, a potentially pathogenic strain of the genus Brachyspira from formalin-fixed human colonic biopsies were visualized by fluorescence in situ hybridization (FISH) with a 16S rRNA-targeting oligonucleotide probe, followed by laser capture microdissection (LCM) of the targeted cells. Direct 16S rRNA gene PCR was performed from the dissected microcolonies, and the subsequent DNA sequence analysis identified the dissected bacterial cells as belonging to the Brachyspira aalborgi cluster 1. The advantage of this technique is the ability to combine the histological recognition of the specific bacteria within the tissue with molecular analysis of 16S rRNA gene or other genes of interest. This method is widely applicable for the identification of noncultivable bacteria and their gene pool from formalin-fixed paraffin-embedded tissue samples.

Brachyspira↗

PubMed2004

Development, characterization and diagnostic application of a monoclonal antibody specific for a proteinase K resistant Lawsonia intracellularis antigen.

Proliferative enteropathy (PE) is one of the most important infections in pigs caused by Lawsonia intracellularis, an obligate intracellular bacterium. The purpose of the present investigation was to develop monoclonal antibodies with specificity to L. intracellularis useful both for diagnostic purposes (by immunohistochemistry) and for bacterial characterization. Several antibody producing hybridomas were established by fusion of mouse myeloma with spleen cells from BALB/c mice immunized with mucosa scrapings of the intestinal mucosa from a L. intracellularis infected pig. A monoclonal antibody (mAb), Law1-DK, isotyped as IgG2b was selected by indirect immunofluorescence antibody test (IFAT). Histological sections of the intestines from pigs affected by proliferative enteropathy and in vitro grown bacteria in cell culture were tested positive for the presence of L. intracellularis with the mAb. A molecule at 21 kDa was recognized by the mAb in a Western blotting analysis when a whole-cell preparation of L. intracellularis was run on a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This antigen was released from L. intracellularis by mild heat treatment and was resistant to proteinase K digestion, suggesting it to be non-protein, e.g., lipopolysaccharide (LPS). This suggestion was supported by its presence in the aqueous phase of a phenol-water extract. The inhibitory effect of periodate oxidation on the antigen-antibody binding confirmed the participation of a carbohydrate epitope. The new mAb was tested highly specific for L. intracellularis by applying in situ hybridization with a L. intracellularis specific probe targeting 16S ribosomal RNA simultaneously with the IFAT.

Animals↗

PubMed2004

Demonstration of Brachyspira aalborgi lineages 2 and 3 in human colonic biopsies with intestinal spirochaetosis by specific fluorescent in situ hybridization.

Sequences of known 16S rRNA genes, derived from sequence analysis of cloned 16S rDNA, were used to design a specific oligonucleotide probe targeting spirochaetes of Brachyspira aalborgi lineages 2 and 3. The probe was used with fluorescent in situ hybridization to study the involvement of these organisms in human intestinal spirochaetosis. Seventeen human colonic biopsies from Norway and Denmark with intestinal spirochaetosis caused by Brachyspira-like organisms different from the type strain of B. aalborgi (lineage 1) were examined. Application of the probe gave a positive signal in two Norwegian biopsies, whereas the 15 other biopsies were hybridization-negative. The positive reaction visualized the spirochaetes as a fluorescent, 3-5 microm-high fringe on the surface epithelium, extending into the crypts. The study verified the presence of B. aalborgi lineages 2 and 3 and identified the bacteria as an aetiological agent of human intestinal spirochaetosis.

Adult↗

PubMed2004

Extensive intestinal spirochaetosis in pigs challenged with Brachyspira pilosicoli.

A field isolate of Brachyspira pilosicoli, the aetiological agent of porcine intestinal spirochaetosis, was inoculated by stomach tube into six 6-week-old pigs. All animals developed loose to watery faeces and were killed successively on days 8, 14 or 17 post-inoculation (day 17 being the end of the study). Mild mucosal reddening and flecks of pus characterized the gross lesions, while diffuse, catarrhal colitis was revealed microscopically in all animals. Intestinal spirochaetosis with moderate to densely packed end-attached B. pilosicoli organisms was revealed extensively on the mucosal surface of the large intestines by light microscopy and fluorescent in situ hybridization. This study is the first to report extensive intestinal spirochaetosis in pigs challenged with B. pilosicoli.

Animals↗

PubMed2002

Culture-independent analysis of gut bacteria: the pig gastrointestinal tract microbiota revisited.

The phylogenetic diversity of the intestinal bacterial community in pigs was studied by comparative 16S ribosomal DNA (rDNA) sequence analysis. Samples were collected from a total of 24 pigs representing a variety of diets, ages, and herd health status. A library comprising 4,270 cloned 16S rDNA sequences obtained directly by PCR from 52 samples of either the ileum, the cecum, or the colon was constructed. In total, 375 phylotypes were identified using a 97% similarity criterion. Three hundred nine of the phylotypes (83%) had a <97% sequence similarity to any sequences in the database and may represent yet-uncharacterized bacterial genera or species. The phylotypes were affiliated with 13 major phylogenetic lineages. Three hundred four phylotypes (81%) belonged to the low-G+C gram-positive division, and 42 phylotypes (11.2%) were affiliated with the Bacteroides and Prevotella group. Four clusters of phylotypes branching off deeply within the low-G+C gram-positive bacteria and one in the Mycoplasma without any cultured representatives were found. The coverage of all the samples was 97.2%. The relative abundance of the clones approximated a lognormal distribution; however, the phylotypes detected and their abundance varied between two libraries from the same sample. The results document that the intestinal microbial community is very complex and that the majority of the bacterial species colonizing the gastrointestinal tract in pigs have not been characterized.

Animals↗