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M Wiedmann

Publications and source records attributed to M Wiedmann.

At least 19 recordsLinked to original sources
PubMed2006

Multilocus sequence typing supports the hypothesis that cow- and human-associated Salmonella isolates represent distinct and overlapping populations.

A collection of 179 human and 156 bovine clinical Salmonella isolates obtained from across New York state over the course of 1 year was characterized using serotyping and a multilocus sequence typing (MLST) scheme based on the sequencing of three genes (fimA, manB, and mdh). The 335 isolates were differentiated into 52 serotypes and 72 sequence types (STs). Analyses of bovine isolates collected on different farms over time indicated that specific subtypes can persist over time on a given farm; in particular, a number of farms showed evidence for the persistence of a specific Salmonella enterica serotype Newport sequence type. Serotypes and STs were not randomly distributed among human and bovine isolates, and selected serotypes and STs were associated exclusively with either human or bovine sources. A number of common STs were geographically widespread. For example, ST6, which includes isolates representing serotype Typhimurium as well as the emerging serotype 4,5,12:i:-, was found among human and bovine isolates in a number of counties in New York state. Phylogenetic analyses supported the possibility that serotype 4,5,12:i:- is closely related to Salmonella serotype Typhimurium. Salmonella serotype Newport was found to represent two distinct evolutionary lineages that differ in their frequencies among human and bovine isolates. A number of Salmonella isolates carried two copies of manB (33 isolates) or showed small deletion events in fimA (nine isolates); these duplication and deletion events may provide mechanisms for the rapid diversification of Salmonella surface molecules. We conclude that the combined use of an economical three-gene MLST scheme and serotyping can provide considerable new insights into the evolution and transmission of Salmonella.

Animals↗
PubMed2006

[Transdermal buprenorphine during pregnancy].

Buprenorphine has been widely used and studied for over 20 years and has been shown to be an effective opioid analgesic. Some years ago a buprenorphine formulation for transdermal therapy of chronic cancer-related and non-cancer-related pain became available. We report the case of a woman who received a lower dosed transdermal buprenorphine patch (3/5 of a 35 microg/h patch corresponding to release of 21 microg/h buprenorphine) during pregnancy without any complication for herself or the child. The patient has now being using the transdermal system for more than 2 years and has reported continuous excellent pain relief. The buprenorphine patch was well tolerated and produced no effect on vigilance over the whole period of administration.

Administration, Cutaneous↗
PubMed2006

Sigma B contributes to Listeria monocytogenes gastrointestinal infection but not to systemic spread in the guinea pig infection model.

Contributions of the alternative sigma factor sigmaB to Listeria monocytogenes infection were investigated using strains bearing null mutations in sigB, prfA, or inlA or in selected inlA or prfA promoter regions. The DeltaP4inlA strain, which has a deletion in the sigmaB-dependent P4inlA promoter, and the DeltasigB strain had significantly reduced invasion efficiencies relative to that of the wild-type strain in the Caco-2 human colorectal epithelial cell line, while the invasion efficiency of a strain bearing a deletion in the partially sigmaB dependent P2prfA promoter region did not differ from that of the wild type. The virulence of the DeltasigB and DeltaP4inlA strains was attenuated in intragastrically inoculated guinea pigs, with the DeltasigB strain showing greater attenuation, while the virulence capacity of the DeltaP2prfA strain was similar to that of the wild-type strain, suggesting that attenuation of virulence due to the DeltasigB mutation does not result from loss of sigmaB-dependent prfA transcription. Our results show that sigmaB-dependent activation of inlA is important for cell invasion and gastrointestinal infection and suggest that sigmaB-regulated genes in addition to inlA appear to contribute to gastrointestinal infection. Interestingly, the virulence of the DeltasigB strain was not attenuated in intravenously infected guinea pigs. We conclude that (i) L. monocytogenes sigmaB plays a critical role in invasion of human host cells, (ii) sigmaB-mediated contributions to invasion are, in part, due to direct effects on inlA transcription but not on prfA transcription, and (iii) sigmaB plays a critical role during the gastrointestinal stage of listeriosis in the guinea pig but is not important for systemic spread of the organism.

Animals↗
PubMed2006

Novel method to identify source-associated phylogenetic clustering shows that Listeria monocytogenes includes niche-adapted clonal groups with distinct ecological preferences.

While phylogenetic and cluster analyses are often used to define clonal groups within bacterial species, the identification of clonal groups that are associated with specific ecological niches or host species remains a challenge. We used Listeria monocytogenes, which causes invasive disease in humans and different animal species and which can be isolated from a number of environments including food, as a model organism to develop and implement a two-step statistical approach to the identification of phylogenetic clades that are significantly associated with different source populations, including humans, animals, and food. If the null hypothesis that the genetic distances for isolates within and between source populations are identical can be rejected (SourceCluster test), then particular clades in the phylogenetic tree with significant overrepresentation of sequences from a given source population are identified (TreeStats test). Analysis of sequence data for 120 L. monocytogenes isolates revealed evidence of clustering between isolates from the same source, based on the phylogenies inferred from actA and inlA (P = 0.02 and P = 0.07, respectively; SourceCluster test). Overall, the TreeStats test identified 10 clades with significant (P < 0.05) or marginally significant (P < 0.10) associations with defined sources, including human-, animal-, and food-associated clusters. Epidemiological and virulence phenotype data supported the fact that the source-associated clonal groups identified here are biologically valid. Overall, our data show that (i) the SourceCluster and TreeStats tests can identify biologically meaningful source-associated phylogenetic clusters and (ii) L. monocytogenes includes clonal groups that have adapted to infect specific host species or colonize nonhost environments.

Biological Evolution↗
PubMed2006

Detection and characterization of Listeria monocytogenes in Sao Jorge (Portugal) cheese production.

Listeria monocytogenes is a foodborne pathogen that can cause serious invasive disease in humans. Because human listeriosis cases have previously been linked to consumption of contaminated cheese, control of this pathogen throughout the cheese production chain is of particular concern. To understand the potential for L. monocytogenes transmission via São Jorge cheese, a Portuguese artisanal cheese variety that bears a Protected Denomination of Origin classification, 357 raw milk, curd, natural whey starter, and cheese samples representative of the production chain of this cheese were collected over one year and tested for the presence of L. monocytogenes and selected physicochemical parameters. Although neither L. monocytogenes nor other Listeria spp. were detected in whey, curd, or cheese samples, 2 of the 105 raw milk samples analyzed were positive for L. monocytogenes. These 2 raw milk isolates represented a ribotype that has previously been linked to multiple human listeriosis outbreaks and cases elsewhere, indicating the potential of these isolates to cause human listeriosis. On average, physicochemical parameters of São Jorge cheese ripened for 4 mo presented values that likely minimize the risk of L. monocytogenes outgrowth during ripening and storage (mean pH = 5.48; mean moisture = 37.79%; mean NaCl concentration = 4.73%). However, some cheese samples evaluated in this study were characterized by physicochemical parameters that may allow growth and survival of L. monocytogenes. Even though our results indicate that raw milk used for São Jorge cheese manufacture as well as finished products is rarely contaminated with L. monocytogenes, continued efforts to control the presence of this pathogen in the São Jorge cheese production chain are urged and are critical to ensure the safety of this product.

Animals↗
PubMed2005

Nationwide outbreak of listeriosis due to contaminated meat.

We used molecular subtyping to investigate an outbreak of listeriosis involving residents of 24 US states. We defined a case as infection with Listeria monocytogenes serotype 4b yielding one of several closely related patterns when subtyped by pulsed-field gel electrophoresis. Patients infected with strains yielding different patterns were used as controls. A total of 108 cases were identified with 14 associated deaths and four miscarriages or stillbirths. A case-control study implicated meat frankfurters as the likely source of infection (OR 17.3, 95% CI 2.4-160). The outbreak ended abruptly following a manufacturer-issued recall, and the outbreak strain was later detected in low levels in the recalled product. A second strain was recovered at higher levels but was not associated with human illness. Our findings suggest that L. monocytogenes strains vary widely in virulence and confirm that large outbreaks can occur even when only low levels of contamination are detected in sampled food. Standardized molecular subtyping and coordinated, multi-jurisdiction investigations can greatly facilitate detection and control of listeriosis outbreaks.

Adolescent↗
PubMed2005

PI3K/Akt-dependent regulation of the transcription factor myocyte enhancer factor-2 in insulin-like growth factor-1- and membrane depolarization-mediated survival of cerebellar granule neurons.

Survival signals such as insulin-like growth factor-1 (IGF-1) or membrane depolarization convey their neuronal protective effects through the activation of signaling networks and nuclear factors. In cerebellar granule neurons, IGF-1 mediates survival primarily through the PI3K/Akt pathway. The function of the transcription factor myocyte enhancer factor-2 (MEF2) is required for mediating membrane depolarization-dependent neuronal survival. However, whether PI3K/Akt regulates MEF2 and the role of MEF2 in IGF-1-mediated survival of neurons are unknown. In addition, the contribution of the PI3K/Akt pathway in membrane depolarization-induced neuronal survival remains undefined. We show here that the PI3K/Akt pathway promotes the survival of cerebellar granule neurons derived from Long-Evans rats following IGF-1 stimulation or membrane depolarization through regulation of MEF2 activity. IGF-1 stimulated the gene transactivation activity of MEF2 and its DNA binding potential. Moreover, regulation of MEF2 function by IGF-1 was dependent on the activity of the PI3K/Akt signaling pathway. Blocking MEF2 function reduced IGF-1-induced survival of cerebellar granule neurons. Membrane depolarization stimulated phosphorylation of Akt in cerebellar granule neurons. Blocking of the PI3K/Akt pathway with either a pharmacological inhibitor of PI3K, LY294002, or dominant negative mutants of PI3K and Akt inhibited the membrane depolarization-induced increase in MEF2 transactivation as well as its DNA binding activity and reduced neuronal survival. Together, these findings provide clear evidence to support an important role of the PI3K/Akt pathway in the regulation of nuclear survival factor MEF2 upon either IGF-1 stimulation or membrane depolarization, thus placing MEF2 as a novel downstream effector of the PI3K/Akt pathway in neurons.

Action Potentials↗
PubMed2005

Malignant oesophago-pleuro-pericardial fistula in a patient with oesophageal carcinoma.

Pericardial and cardiac fistulae secondary to oesophageal or gastric tumours are a rare complication. We report about a 50-year-old male patient with a 10-month history of distal oesophageal carcinoma with lung and liver metastases who was referred to our hospital after 6 cycles of palliative chemotherapy at the beginning of March 2004. The patient presented with dysphagia, dyspnea, tachycardia, and hypotension. Purulent pericardial and bilateral pleural effusion was diagnosed, and the patient was treated with antibiotics, repeated pleurocentesis and pericardial drainage with daily polihexanide lavage. Oesophagogastroduodenoscopy, Peritrast swallow and computed tomographic scans of chest revealed a malignant oesophago-pleuro-pericardial fistula. A total of three coated, expandable metal stents were inserted into the oesophagus, which sealed successfully the fistula. Unfortunately, the patient succumbed to his carcinoma three months later.

Esophageal Fistula↗
PubMed2005

[Current diagnostics and therapy for carcinomas of the biliary tree and gallbladder].

Carcinoma of the biliary tree are rare tumours of the gastrointestinal tract with a rising incidence during the last years. Biliary neoplasms are classified into intra- and extrahepatic cholangiocarcinoma (Klatskin tumour, middle and distal extrahepatic tumours), gallbladder cancer, and ampullary carcinoma. Transformation of normal into malignant bile duct tissue requires a chain of consecutive gene mutations, similar to the adenoma-dysplasia-carcinoma-sequence in colon cancer. Abdominal ultrasound, combined non-invasive magnetic resonance cholangiography/tomography (MRC/MRT), and facultatively endoscopic retrograde cholangiography (ERC) for unclear diagnosis, represent the gold standard for primary diagnosis. For ampullary carcinoma, endosonography and endoscopic biopsy are the diagnostic tools of choice. Cure is attainable only by formal curative radical surgical resection. Increasing surgical radicality within the last years enabled clearly improved 5-year survival rates. In contrast, there has been no clinical benefit for adjuvant and neoadjuvant therapies. For palliation, bile duct stenting and photodynamic therapy are established methods. Radio- and chemotherapy should be reserved for clinical studies. New therapeutic approaches include brachytherapy, the use of modern chemotherapeutics, COX-2- and tyrosine kinase-receptor-inhibitors.

Algorithms↗
PubMed2005

[Is 18F-FDG-PET suitable for therapy monitoring after palliative photodynamic therapy of non-resectable hilar cholangiocarcinoma?].

BACKGROUND: If existing biliary drainage is insufficient, photodynamic therapy (PDT, laser treatment after application of a photosensitizer) is an already established adjunct to palliative therapy for progressing hilar cholangiocarcinoma (Klatskin tumours), since it prolongs survival and improves quality of life. Experimental studies of other tumour entities showed that (18)F-FDG-PET ( (18)F-fluorodeosxyglucose-positron emission tomography) may play a role in monitoring tumour response to PDT. Furthermore, previous studies have revealed a high accuracy of this method for the detection of hilar cholangiocarcinoma. Therefore, the aim of the present study was to investigate the feasibility of (18)F-FDG-PET as a follow-up screening method in patients with hilar cholangiocarcinoma who underwent PDT. PATIENTS AND METHODS: 10 patients were examined by (18)F-FDG-PET before and 4 - 6 weeks after PDT. The following parameters were evaluated: maximum and mean SUV in the tumour, the ratio of maximum SUV in the tumour and mean SUV in the liver, the vital tumour volume, as well as bilirubin and CA 19 - 9 levels. RESULTS: All tumours were detected by (18)F-FDG-PET. Within a period of 4 - 6 weeks after PDT the cholestasis parameter bilirubin decreased significantly. However, SUV-associated parameters did not show a significant change after treatment while the estimated vital tumour volume even increased. DISCUSSION: PDT does not effect a relevant reduction of tumour mass in non-resectable hilar cholangiocarcinoma. However, PDT leads to a significant reduction of cholestasis. If (18)F-FDG-PET is suitable for monitoring the effect of new palliative therapeutic approaches, like brachytherapy, the use of modern chemotherapeuticals, COX-2 and receptor-tyrosine kinase inhibitors, perhaps also in combination with PDT, has to be further investigated.

Bile Duct Neoplasms↗
PubMed2005

Ceftiofur-resistant Salmonella strains isolated from dairy farms represent multiple widely distributed subtypes that evolved by independent horizontal gene transfer.

Salmonella is the leading cause of known food-borne bacterial infections in the United States, with an incidence rate of approximately 15 cases per 100,000 people. The rise of antimicrobial-resistant Salmonella subtypes, including the appearance of subtypes resistant to ceftriaxone, represents a particular concern. Ceftriaxone is used to treat invasive cases of Salmonella in children and is closely related to ceftiofur, an antibiotic commonly used to treat diseases of cattle. In order to develop a better understanding of the evolution and transmission of ceftiofur resistance in Salmonella, we characterized ceftiofur-resistant and -sensitive Salmonella isolates from seven New York dairy farms. A total of 39 isolates from these seven farms were analyzed for evolutionary relatedness (by DNA sequencing of the Salmonella genes fimA, manB, and mdh), antibiotic resistance profiles, and the presence of bla(CMY-2), a beta-lactamase gene associated with resistance to cephalosporins. Our data indicate that (i) resistance to ceftriaxone and ceftiofur was highly correlated with the presence of bla(CMY-2); (ii) ceftiofur-resistant Salmonella strains were geographically widespread, as shown by their isolation from farms located throughout New York State; (iii) ceftiofur-resistant Salmonella strains isolated from farms represent multiple distinct subtypes and evolutionary lineages, as determined by serotyping, DNA sequence typing, and antimicrobial-resistance profiles; and (iv) ceftiofur-resistant Salmonella strains evolved by multiple independent acquisitions of an identical bla(CMY-2) allele and by clonal spread of ceftiofur-resistant subtypes.

Alleles↗
PubMed2005

Select Listeria monocytogenes subtypes commonly found in foods carry distinct nonsense mutations in inlA, leading to expression of truncated and secreted internalin A, and are associated with a reduced invasion phenotype for human intestinal epithelial cells.

The surface protein internalin A (InlA) contributes to the invasion of human intestinal epithelial cells by Listeria monocytogenes. Screening of L. monocytogenes strains isolated from human clinical cases (n=46), foods (n=118), and healthy animals (n=58) in the United States revealed mutations in inlA leading to premature stop codons (PMSCs) in L. monocytogenes ribotypes DUP-1052A and DUP-16635A (PMSC mutation type 1), DUP-1025A and DUP-1031A (PMSC mutation type 2), and DUP-1046B and DUP-1062A (PMSC mutation type 3). While all DUP-1046B, DUP-1062A, DUP-16635A, and DUP-1031A isolates (n=76) contained inlA PMSCs, ribotypes DUP-1052A and DUP-1025A (n=72) contained isolates with and without inlA PMSCs. Western immunoblotting showed that all three inlA PMSCs result in the production of truncated and secreted InlA. Searches of the Pathogen Tracker database, which contains subtype and source information for more than 5,000 L. monocytogenes isolates, revealed that the six ribotypes shown to contain isolates with inlA PMSCs were overall more commonly isolated from foods than from human listeriosis cases. L. monocytogenes strains carrying inlA PMSCs also showed significantly (P=0.0004) reduced invasion of Caco-2 cells compared to isolates with homologous 3' inlA sequences without PMSCs. Invasion assays with an isogenic PMSC mutant further supported the observation that inlA PMSCs lead to reduced invasion of Caco-2 cells. Our data show that specific L. monocytogenes subtypes which are common among U.S. food isolates but rare among human listeriosis isolates carry inlA mutations that are associated with, and possibly at least partially responsible for, an attenuated invasion phenotype.

Bacterial Proteins↗
PubMed2005

Evolution and molecular phylogeny of Listeria monocytogenes isolated from human and animal listeriosis cases and foods.

To probe the evolution and phylogeny of Listeria monocytogenes from defined host species and environments, L. monocytogenes isolates from human (n = 60) and animal (n = 30) listeriosis cases and food samples (n = 30) were randomly selected from a larger collection of isolates (n = 354) obtained in New York State between 1999 and 2001. Partial sequencing of four housekeeping genes (gap, prs, purM, and ribC), one stress response gene (sigB), and two virulence genes (actA and inlA) revealed between 11 (gap) and 33 (inlA) allelic types as well as 52 sequence types (unique combination of allelic types). actA, ribC, and purM demonstrated the highest levels of nucleotide diversity (pi > 0.05). actA and inlA as well as prs and the hypervariable housekeeping genes ribC and purM showed evidence of horizontal gene transfer and recombination. actA and inlA also showed evidence of positive selection at specific amino acid sites. Maximum likelihood phylogenies for all seven genes confirmed that L. monocytogenes contains two deeply separated evolutionary lineages. Lineage I was found to be highly clonal, while lineage II showed greater diversity and evidence of horizontal gene transfer. Allelic types were exclusive to lineages, except for a single gap allele, and nucleotide distance within lineages was much lower than that between lineages, suggesting that genetic exchange between lineages is rare. Our data show that (i) L. monocytogenes is a highly diverse species with at least two distinct phylogenetic lineages differing in their evolutionary history and population structure and (ii) horizontal gene transfer as well as positive selection contributed to the evolution of L. monocytogenes.

Animal Feed↗
PubMed2004

[Conservative and interventional endoscopic therapy of biliary tract carcinoma].

Endoscopic therapy is central to the palliative treatment of bile duct carcinoma. In obstructive jaundice, biliary drainage has few complications and relieves symptoms reliably. It can prevent further complications and is indispensable to the treatment of cholangitis. The principal drawback of biliary stents is stent occlusion and cholangitis. Prophylactic antibiotics were not proven to be effective. Technical details concerning material, number and location of stents await further clarification. Photodynamic therapy is an emerging adjunct to palliative therapy of biliary cancer. Preoperative biliary drainage in obstructive jaundice is not warranted as a routine intervention. It may be indicated, though, as preoperative bridging or to allow liver function to recover before major hepatic surgery. Finally, stenting of postoperative bile duct stenosis is gaining increasing acceptance.

Biliary Tract Neoplasms↗
PubMed2004

A severe case of systemic lupus erythematosus with cerebral involvement.

We describe an 18-year-old girl who presented with severe systemic lupus erythematosus with multiple organ involvement. The disease was further complicated by recurrent seizures and intracerebral left parieto-occipital bleeding that required neurosurgical treatment. Postoperative rebleeding occurred due to disseminated intravascular coagulation and platelet dysfunction. Catastrophic antiphospholipid syndrome was suspected, but could not be confirmed during follow-up. Additional treatment with plasmapheresis and intravenous pulse cyclophosphamide in combination with corticosteroids was started. Liquor drainage via a ventriculo-peritoneal (vp)-shunt was necessary because of a hydrocephalus malresorptivus. The patient's recovery was slow and incomplete (cachexia and amaurosis persisted). Follow-up was further complicated by an intraperitoneal vp-shunt cyst, which was initially treated conservatively, but finally had to be revised operatively.

Adolescent↗
PubMed2004

Natural atypical Listeria innocua strains with Listeria monocytogenes pathogenicity island 1 genes.

Identification of bona fide Listeria isolates into the six species of the genus normally requires only a few tests. Aberrant isolates do occur, but even then only one or two extra confirmatory tests are generally needed for identification to species level. We have discovered a hemolytic-positive, rhamnose and xylose fermentation-negative Listeria strain with surprising recalcitrance to identification to the species level due to contradictory results in standard confirmatory tests. The issue had to be resolved by using total DNA-DNA hybridization testing and then confirmed by further specific PCR-based tests including a Listeria microarray assay. The results show that this isolate is indeed a novel one. Its discovery provides the first fully documented instance of a hemolytic Listeria innocua strain. This species, by definition, is typically nonhemolytic. The L. innocua isolate contains all the members of the PrfA-regulated virulence gene cluster (Listeria pathogenicity island 1) of L. monocytogenes. It is avirulent in the mouse pathogenicity test. Avirulence is likely at least partly due to the absence of the L. monocytogenes-specific allele of iap, as well as the absence of inlA, inlB, inlC, and daaA. At least two of the virulence cluster genes, hly and plcA, which encode the L. monocytogenes hemolysin (listeriolysin O) and inositol-specific phospholipase C, respectively, are phenotypically expressed in this L. innocua strain. The detection by PCR assays of specific L. innocua genes (lin0198, lin0372, lin0419, lin0558, lin1068, lin1073, lin1074, lin2454, and lin2693) and noncoding intergenic regions (lin0454-lin0455 and nadA-lin2134) in the strain is consistent with its L. innocua DNA-DNA hybridization identity. Additional distinctly different hemolytic L. innocua strains were also studied.

Animals↗
PubMed2004

Ecology and transmission of Listeria monocytogenes infecting ruminants and in the farm environment.

A case-control study involving 24 case farms with at least one recent case of listeriosis and 28 matched control farms with no listeriosis cases was conducted to probe the transmission and ecology of Listeria monocytogenes on farms. A total of 528 fecal, 516 feed, and 1,012 environmental soil and water samples were cultured for L. monocytogenes. While the overall prevalence of L. monocytogenes in cattle case farms (24.4%) was similar to that in control farms (20.2%), small-ruminant (goat and sheep) farms showed a significantly (P < 0.0001) higher prevalence in case farms (32.9%) than in control farms (5.9%). EcoRI ribotyping of clinical (n = 17) and farm (n = 414) isolates differentiated 51 ribotypes. L. monocytogenes ribotypes isolated from clinical cases and fecal samples were more frequent in environmental than in feed samples, indicating that infected animals may contribute to L. monocytogenes dispersal into the farm environment. Ribotype DUP-1038B was significantly (P < 0.05) associated with fecal samples compared with farm environment and animal feedstuff samples. Ribotype DUP-1045A was significantly (P < 0.05) associated with soil compared to feces and with control farms compared to case farms. Our data indicate that (i) the epidemiology and transmission of L. monocytogenes differ between small-ruminant and cattle farms; (ii) cattle contribute to amplification and dispersal of L. monocytogenes into the farm environment, (iii) the bovine farm ecosystem maintains a high prevalence of L. monocytogenes, including subtypes linked to human listeriosis cases and outbreaks, and (iv) L. monocytogenes subtypes may differ in their abilities to infect animals and to survive in farm environments.

Agriculture↗