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M Gottschalk

Publications and source records attributed to M Gottschalk.

At least 37 records · Page 2Linked to original sources
PubMed2001

Experimental airborne transmission of Streptococcus suis capsular type 2 in pigs.

Experimental airborne transmission of Streptococcus suis type 2 was studied in specific pathogen free piglets. Forty piglets were allotted to five groups of eight 7-week-old animals and housed in three separated units. Negative control pigs (group 1) were housed in unit A and infected batches were housed in units B (group 2) and C (groups 4). In units B and C, non-inoculated groups (groups 3 and 5, respectively), 40 cm distant from the respective inoculated group and without any physical contact between them, also took place. Six animals of groups 2 and 4 were inoculated intravenously with 2 x 10(8) colony forming units (cfu) of a mild and a high virulent S. suis strains, respectively. The remaining animals in these groups and pigs from groups 1, 3, 5 received broth medium in the same way. Differences among virulence of S. suis capsular type 2 were observed in inoculated pigs of groups 2 and 4. Pigs from group 2 became carriers, showing only mild symptoms. By contrast, animals from group 4 presented an acute form of the disease. All the indirect contact pigs in groups 3 and 5 had S. suis in palatine tonsils from day 6 after the infection and they presented clinical manifestations similar to those observed in experimentally infected pigs. Two direct contact animals were also contaminated in the upper respiratory tract but surprisingly they did not show any symptoms. Airborne transmission of S. suis in experimentally pigs was demonstrated in the present study. Indirect infections, as described in this study, are a more realistic way to infect pigs than other experimental procedures and may be used to further study the pathogenesis of the infection caused by this important pathogen.

Animals↗
PubMed2001

Microsecond exchange of internal water molecules in bacteriorhodopsin.

The proton-conducting pathway of bacteriorhodopsin (BR) contains at least nine internal water molecules that are thought to be key players in the proton translocation mechanism. Here, we report the results of a multinuclear (1H, 2H, 17O) magnetic relaxation dispersion (MRD) study with the primary goal of determining the rate of exchange of these internal water molecules with bulk water. This rate is of interest in current attempts to elucidate the molecular details of the proton translocation mechanism. The relevance of water exchange kinetics is underscored by recent crystallographic findings of substantial variations in the number and locations of internal water molecules during the photocycle. Moreover, internal water exchange is believed to be governed by conformational fluctuations in the protein and can therefore provide information about the thermal accessibility of functionally important conformational substates. The present 2H and 17O MRD data show that at least seven water molecules, or more if they are orientationally disordered, in BR have residence times (inverse exchange rate constant) in the range 0.1-10 micros at 277 K. At least five of these water molecules have residence times in the more restrictive range 0.1-0.5 micros. These results show that most or all of the deeply buried water molecules in BR exchange on a time-scale that is short compared to the rate-limiting step in the photocycle. The MRD measurements were performed on BR solubilized in micelles of octyl glucoside. From the MRD data, the rotational correlation time of detergent-solubilized BR was determined to 35 ns at 300 K, consistent with a monomeric protein in complex with about 150 detergent molecules. The solubilized protein was found to be stable in the dark for at least eight months at 277 K.

Bacteriorhodopsins↗
PubMed2001

Identification and detection of Actinobacillus pleuropneumoniae by PCR based on the gene apxIVA.

The apxIVA gene, a recently discovered RTX determinant of Actinobacillus pleuropneumoniae, was shown to be species-specific. DNA hybridization experiments using probes for various regions of apxIVA revealed that the 3'-terminus of this gene was present in all 14 serotypes of A. pleuropneumoniae but absent from phylogenetically related species. A primer pair spanning this region specifically amplified a 422bp fragment in PCR experiments with DNA from the reference strains of the 14 serotypes and 194 field strains isolated from various geographic locations worldwide. DNA sequence analysis of PCR products derived from all serotypes were identical except in serotypes 3, 8, and 10, which showed minor differences. The PCR did not amplify any product when DNA from 17 different bacterial species closely related to A. pleuropneumoniae was used as template. In addition, the PCR was negative with DNA of several Actinobacillus sp. which were initially characterized as A. pleuropneumoniae using routine phenotypic and serological analyses but which were subsequently shown by 16S rRNA sequence analysis to belong to yet undefined Actinobacillus species. The sensitivity of the PCR was determined to be 10pg of A. pleuropneumoniae DNA. A set of nested primers amplified a 377bp fragment specifically with A. pleuropneumoniae DNA. DNA titration experiments using the flanking and nested primer pairs showed an improved level of sensitivity to approximately 10fg of genomic DNA. The nested PCR was used to monitor the spread of A. pleuropneumoniae in pigs experimentally infected with a virulent serotype 1 strain and housed in a controlled environment facility. A. pleuropneumoniae DNA could be detected by nested PCR in nasal swab samples of infected pigs receiving either a high dose (5x10(5)) or a low dose (1x10(4)) challenge and in unchallenged cohorts that were contact-infected by the inoculated animals. Furthermore, PCR confirmed the presence of A. pleuropneumoniae in 16/17 homogenates from necrotic lung lesions, while the bacterium was successfully recovered from 13 of these lesions by culture.

Actinobacillus Infections↗
PubMed2001

[Familial myoclonus-renal failure syndrome].

In 1986 Andermann et al. described a syndrome presenting with renal failure, myoclonus, cerebellar symptoms, and epilepsy. They presumed a hereditary cause. We describe the first appearance of this syndrome in Europe, affecting three family members with comparable symptoms. Two of these patients were treated by us, and the third, already decreased, is described according to the available reports. The first clinical symptoms were manifested between the ages of 14 and 20. A female patient suffered from compensated kidney insufficiency and her two brothers aged 18 and 26 required dialysis. Biopsy of kidney tissue revealed nonspecific nephritis. All cases showed a cerebellar syndrome and action myoclonus. Two of them were diagnosed with epilepsy and grand mal seizures, and all suffered from demyelinizing or mixed polyneuropathy. Anamnesis of the family seems to indicate autosomal recessive inheritance.

Adolescent↗
PubMed2001

The design and implementation of a restorative care model for home care.

PURPOSE: The increasing demand for geriatric home-based care makes it timely to examine how the existing system can become most effective and efficient in promoting the functional outcomes of older patients. DESIGN AND METHODS: A multidisciplinary work group identified home care agency policies, misconceptions of older adults and their caregivers, and practice patterns of nurses, therapists, and home health aides that can impede patients' progress toward functional independence. This article describes the process that one home care agency used to remove these obstacles. RESULTS AND IMPLICATIONS: The work group developed and implemented a restorative model of care that integrates the medical treatments for acute disease processes and the personal care and rehabilitative interventions directed toward chronic disabilities, to improve the functional outcomes of older adults receiving home care.

Activities of Daily Living↗
PubMed2001

Prevalence of hepatitis E virus antibodies in Canadian swine herds and identification of a novel variant of swine hepatitis E virus.

Swine hepatitis E virus is a newly identified potentially zoonotic virus from pigs of particular concern for possible direct transmission to a human xenotransplant recipient by organ transplantation. In the present study, prevalence of serum antibodies to hepatitis E virus was examined in Canadian swine herds. A total of 998 serum samples collected from 6-month-old healthy slaughter hogs were examined by enzyme immunoassay and Western blot analysis for antibodies to the recombinant open reading frame 3 (ORF3) protein of hepatitis E virus expressed in Escherichia coli. These samples represented more than 80 different swine production units from five major swine-producing provinces across Canada. From this study, 594 samples (59.4%) were found to be positive for hepatitis E virus antibody. The seroprevalence was higher in Quebec (88.8%) and Ontario (80.1%) than in Alberta and Saskatchewan (38.3%). By PCR using a pair of oligonucleotide primers deduced from the ORF2 sequence of human hepatitis E virus, a specific hepatitis E virus sequence was recovered from feces of pigs. The nucleotide sequence identity between the U.S. swine hepatitis E virus and the Canadian isolate (SK3) was only 85.8%, suggesting that genotypic variations may exist in swine hepatitis E virus in North America. Among 165 serum samples collected from humans in Saskatchewan, 2.4% were found to be positive for antibodies to the hepatitis E virus ORF3 protein. Our data indicate that hepatitis E virus is highly prevalent in commercial swine populations in Canada and support the suggestion that the swine hepatitis E virus may be an important zoonotic agent for humans.

Animals↗
PubMed2001

A disease-associated cellular immune response in type 1 diabetics to an immunodominant epitope of insulin.

The 9-23 amino acid region of the insulin B chain (B9-23) is a dominant epitope recognized by pathogenic T lymphocytes in nonobese diabetic mice, the animal model for type 1 diabetes. We describe herein similar (B9-23)-specific T-cell responses in peripheral lymphocytes obtained from patients with recent-onset type 1 diabetes and from prediabetic subjects at high risk for disease. Short-term T-cell lines generated from patient peripheral lymphocytes showed significant proliferative responses to (B9-23), whereas lymphocytes isolated from HLA and/or age-matched nondiabetic normal controls were unresponsive. Antibody-mediated blockade demonstrated that the response was HLA class II restricted. Use of the highly sensitive cytokine-detection ELISPOT assay revealed that these (B9-23)-specific cells were present in freshly isolated lymphocytes from only the type 1 diabetics and prediabetics and produced the proinflammatory cytokine IFN-gamma. This study is, to our knowledge, the first demonstration of a cellular response to the (B9-23) insulin epitope in human type 1 diabetes and suggests that the mouse and human diseases have strikingly similar autoantigenic targets, a feature that should facilitate development of antigen-based therapeutics.

Adolescent↗
PubMed2001

Specific detection by PCR of Streptococcus agalactiae in milk.

The aim of this study was to develop a simple and specific method for direct detection of Streptococcus agalactiae from cow's milk. The method was based on polymerase chain reaction (PCR) using species-specific and universal primers derived from the 16S rRNA gene. The amplification product was verified by restriction endonuclease digest and sequencing. Specific identification was proven on a collection of 147 S. agalactiae isolates of bovine and human origin. In addition, 17 strains belonging to different bacterial species that potentially can be found in milk samples also tested negative. The PCR developed was used for direct detection of S. agalactiae in milk, using for the first time with gram-positive bacteria the nucleic acid-binding properties of diatomaceous earth. The test, which has high specificity, high sensitivity (100 cfu/mL), and can be carried out in less than 24 h, represents an innovative diagnostic tool for the detection of S. agalactiae in milk.

Animals↗
PubMed2001

Decrease of the adhesion of Streptococcus suis serotype 2 mutants to embryonic bovine tracheal cells and porcine tracheal rings.

Streptococcus suis is an important swine pathogen that may be present in the tonsils of pigs that show no signs of illness. Because adhesion to host cells may be important in the carrier state, this study was undertaken to investigate adhesion to host cells by S. suis mutant strains defective in expression of a 39-kDa protein. Mutant strains of S. suis were generated by transposon Tn916 mutagenesis and were tested for adhesion to embryonic bovine tracheal cells and porcine tracheal rings. Compared with the parent strain, there was a significant reduction in adherence of 3 mutant strains to both bovine tracheal cells and porcine tracheal rings.

Animals↗
PubMed2001

Experimental infection of specific pathogen free piglets with French strains of Streptococcus suis capsular type 2.

A standardized model of Streptococcus suis type 2 infection in specific-pathogen-free piglets, housed in high-security barns, was used to compare the virulence of 3 French field strains of S. suis serotype 2 isolated from tonsils of a healthy pig (strain 65) or from diseased pigs (meningitis, strain 166', or septicemia, strain 24). In one of the 2 trials, 7-week-old pigs, in 3 groups of 8, were inoculated intravenously with 2 x 10(8) colony-forming units of S. suis type 2. In each group, 1 uninfected animal was a sentinel. Eight animals were also used as negative control group. The experiment was repeated under similar conditions with strains 65 and 166'. Virulence differed markedly among these S. suis strains when clinical signs, zootechnical performances, lesions, and bacteriological data were analyzed. Strain 65 did not induce clinical signs in inoculated pigs. In contrast, pigs infected with the other 2 strains exhibited clinical signs and typical lesions of S. suis type 2 infections. Differences in virulence were also observed between the 2 virulent strains. Sentinel animals exhibited the same manifestations as those recorded in inoculated piglets. Results were similar in the second trial, indicating that under the present experimental conditions, results were reproducible. The standardized conditions described in this study could be a useful tool to further study about the S. suis infection.

Animals↗
PubMed2000

The pathogenesis of the meningitis caused by Streptococcus suis: the unresolved questions.

Streptococcus suis is one of the most important swine pathogens world-wide. Among the serotypes described, type 2 is the serotype most frequently associated with disease. Despite increasing research in recent years, knowledge of virulence factors and the pathogenesis of the infection remain limited. This review discusses the currently available information on S. suis serotype 2 virulence factors and the pathogenesis of the meningitis caused by this important bacterial species. In addition, some hypotheses on the critical steps of the infection, such as bacterial invasion from mucosal surfaces to the bloodstream, survival of bacteria in blood, and invasion from blood into the central nervous system, are presented. Finally, the role that the stimulation of the immune system of animals (inflammatory reaction) could play during infection is also discussed. A complete understanding of the cell-interacting pathways that S. suis may follow inside the host could give important insights into the progression of disease. Further studies to delineate the mechanisms through which S. suis induces meningitis will contribute to the development of potential therapies for S. suis infections.

Animals↗
PubMed2000

Isolation and characterization of a capsule-deficient mutant of Actinobacillus pleuropneumoniae serotype 1.

The capsular polysaccharides (CPS) play a major role in pathogenicity of Actinobacillus pleuroIpneumoniae, the causative agent of porcine pleuropneumonia. The purpose of the present study was to isolate a mutant in CPS biosynthesis by using a mini-Tn 10 transposon mutagenesis system and evaluate its adherence to host cells. One mutant apparently did not possess CPS as it did not react with a monoclonal antibody against A. pleuropneumoniae serotype 1 capsular antigen. Absence of capsule was confirmed by flow cytometry and also by transmission electron microscopy after polycationic ferritin labelling. The site of insertion of the mini-Tn 10 was determined and found to be in the cpxC gene. Its gene product, CpxC, is a protein involved in polysaccharide transport across the cytoplasmic membrane during CPS biosynthesis. Use of piglet tracheal frozen sections indicated that the CPS mutant adhered significantly (P=0.0001) more than the parent strain. The non-capsular mutant was less virulent in pigs compared to the parent strain and showed no mortality in experimentally infected pigs. The CPS mutant was however resistant to pig serum. This CPS mutant is the first A. pleuropneumoniae mutant in a CPS transport gene. It is also the first time that adherence of a CPS mutant of A. pleuropneumoniae is evaluated. Our observations indicate that capsular polysaccharides of A. pleuropneumoniae serotype 1 are not involved in adherence to piglet tracheal frozen sections but rather mask, at least in part, the adhesive functions.

Actinobacillus Infections↗
PubMed2000

Actinobacillus pleuropneumoniae surface polysaccharides: their role in diagnosis and immunogenicity.

Actinobacillus pleuropneumoniae is an important pig pathogen that is responsible for swine pleuropneumonia, a highly contagious respiratory infection. Knowledge of the importance, composition and structural determination of the major antigens involved in virulence provides crucial information that could lead to the development of a rationale for the production of specific serodiagnostic tools as well as vaccine development. Thus, efforts have been devoted to study mainly A. pleuropneumoniae virulence determinants with special emphasis on the Apx toxins (for A. pleuropneumoniae RTX toxins). In comparison, little attention has been given to the surface polysaccharides, which include capsular polysaccharides (CPS) and cell-wall lipopolysaccharides (LPS). Here, we review current knowledge on CPS and LPS of A. pleuropneumoniae used as diagnostic tools to monitor the infection and as immunogens for inclusion in vaccine preparations for animal protection.

Actinobacillus Infections↗
PubMed2000

Characterization of Ricinus communis phloem profilin, RcPRO1.

The mature, functional sieve tube, which forms the conduit for assimilate distribution in higher plants, is dependent upon protein import from the companion cells for maintenance of the phloem long-distance translocation system. Using antibodies raised against proteins present in the sieve-tube exudate of Ricinus communis (castor bean) seedlings, a cDNA was cloned which encoded a putative profilin, termed RcPRO1. Expression and localization studies indicated that RcPRO1 mRNA encodes a phloem profilin, with some expression occurring in epidermal, cortex, pith and xylem tissue. Purified, recombinant RcPRO1 was functionally equivalent to recombinant maize profilin ZmPRO4 in a live cell nuclear displacement assay. The apparent equilibrium dissociation constant for RcPRO1 binding to plant monomeric (G-)actin was lower than the previously characterized maize profilins. Moreover, the affinity of RcPRO1 for poly-L-proline (PLP) was significantly higher than that for recombinant maize profilins. Within the sieve-tube exudate, profilin was present in 15-fold molar excess to actin. The data suggest that actin filament formation is prevented within the assimilate stream. These results are discussed in terms of the unique physiology of the phloem.

Actins↗
PubMed2000

Streptococcus suis serotype 2 interactions with human brain microvascular endothelial cells.

Streptococcus suis serotype 2 is a worldwide causative agent of many forms of swine infection and is also recognized as a zoonotic agent causing human disease, including meningitis. The pathogenesis of S. suis infections is poorly understood. Bacteria circulate in the bloodstream in the nonimmune host until they come in contact with brain microvascular endothelial cells (BMEC) forming the blood-brain barrier. The bacterial polysaccharide capsule confers antiphagocytic properties. It is known that group B streptococci (GBS) invade and damage BMEC, which may be a primary step in the pathogenesis of neonatal meningitis. Interactions between S. suis and human endothelial cells were studied to determine if they differ from those between GBS and endothelial cells. Invasion assays performed with BMEC and human umbilical vein endothelial cells demonstrated that unlike GBS, S. suis serotype 2 could not invade either type of cell. Adherence assays showed that S. suis adhered only to BMEC, whereas GBS adhered to both types of cell. These interactions were not affected by the presence of a capsule, since acapsular mutants from both bacterial species adhered similarly compared to the wild-type strains. Lactate dehydrogenase release measurements indicated that some S. suis strains were highly cytotoxic for BMEC, even more than GBS, whereas others were not toxic at all. Cell damage was related to suilysin (S. suis hemolysin) production, since only suilysin-producing strains were cytotoxic and cytotoxicity could be inhibited by cholesterol and antisuilysin antibodies. It is possible that hemolysin-positive S. suis strains use adherence and suilysin-induced BMEC injury, as opposed to direct cellular invasion, to proceed from the circulation to the central nervous system.

Bacterial Adhesion↗
PubMed2000

Characterization of Streptococcus agalactiae isolates of bovine and human origin by randomly amplified polymorphic DNA analysis.

Streptococcus agalactiae is considered one of the major causes of bovine intramammary infections. It is also found in the vaginas of women without any apparent clinical symptoms, but reports of neonatal infections, causing significant morbidity, are relatively frequent. The aim of this study was to evaluate the genetic diversity of S. agalactiae strains isolated from bovine milk and from asymptomatic women in Québec, Canada, by randomly amplified polymorphic DNA (RAPD) analysis. A total of 185 bovine isolates and 38 human isolates were first serotyped for capsular polysaccharide by double diffusion in agarose gel (bovine isolates) and coagglutination (human isolates). Strains were then studied by RAPD using 3 primers, designated OPS11, OPB17, and OPB18, which were selected from 12 primers. Thirty-eight percent of bovine isolates and 82% of human isolates could be serotyped. Prevalent serotypes were type III (28%) for bovine isolates and types V (26%) and III (24%) for human isolates. RAPD results showed that, taken together, all isolates (of bovine and human origin) shared 58% similarity. Ninety-four percent of these isolates were clustered in four groups (I, II, III, and IV) with 70% similarity among them. Three clusters, A (48 isolates), B (14 isolates), and C (32 isolates), with 79 to 80% similarity were identified within group IV, whereas the three other groups did not present any clusters. Despite some clustering of human isolates, relatively high diversity was seen among them. Relatively high heterogeneity was observed with the RAPD profiles, not only for field strains belonging to different serotypes but also for those within a given serotype.

Animals↗