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Challenge Studies (challenge + studies)
Selected AbstractsCHALLENGE STUDIES WITH PROTEOLYTIC CLOSTRIDIUM BOTULINUM IN YEAST AND CHEMICALLY LEAVENED CRUMPETS PACKAGED UNDER MODIFIED ATMOSPHERESJOURNAL OF FOOD SAFETY, Issue 2 2003DAPHNE PHILLIPS DAIFAS ABSTRACT Challenge studies were done with proteolytic Clostridium botulinum (103 spores/g) in yeast-and chemical-leavened crumpets (50-g) packaged in air with an ethanol vapor (2-G Ethicap®) generator or in 100% CO2 and stored at ambient temperature (25C) for 30 days. Neurotoxin was detected in all gas- (CO2) packaged crumpets after 5 days regardless of the method of leavening. While neurotoxin was delayed for 10 days in chemical-leavened Ethicap®-packaged crumpets, it was not detected in any similarly packaged yeast-leavened crumpets throughout storage. This inhibition of growth and neurotoxin production by C. botulinum was attributed to the production of ethanol by Saccharomyces cerevisiae in the yeast leavened crumpets, in conjunction with the ethanol vapor generated by the Ethicap® sachets (2-G), to levels to inhibitory to the growth of C. botulinum (>2.8% v/v). Subsequent challenge studies in sterile crumpets inoculated with either C. botulinum (103 spores/g) or a co-inoculum of C. botulinum (103 spores/g) and S. cerevisiae (105 CFU/g) confirmed the significant role (p<0.001) of S. cerevisiae in enhancing the antibotulinal efficacy of ethanol vapor. These studies showed that the method of crumpet leavening could have a profound effect on the growth of and neurotoxin production by C. botulinum in crumpets packaged under modified atmospheres. [source] Role of Alicyclobacillus acidoterrestris in the development of a disinfectant taint in shelf-stable fruit juiceLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2003N. Jensen Abstract Aims: This study was undertaken to identify the bacterium and metabolic products contributing to a disinfectant taint in shelf-stable fruit juice and to determine some of the growth conditions for the organism. Methods and Results: Microbiological examination of tainted and untainted fruit juice drinks detected low numbers of acid-dependent, thermotolerant, spore-forming bacteria in the tainted juices only. The presence of ,-cyclohexyl fatty acids was confirmed in two of the isolates by cell membrane fatty acid analysis. The isolates were subsequently identified as Alicyclobacillus acidoterrestris by partial 16S rDNA sequencing. Studies on the isolates showed growth at pH 2·5,6·0 and 19·5,58 °C. Gas chromatography/mass spectrometry (GC/MS) was used to identify and quantify 2,6-dibromophenol (2,6-DBP) and 2,6-dichlorophenol (2,6-DCP) in the tainted juice. Challenge studies in a mixed fruit drink inoculated with the two isolates and the type strain of A. acidoterrestris, incubated at 44,46 °C for 4 d, showed the production of both metabolites, which were confirmed and quantified by GC/MS. Conclusions: The results show that A. acidoterrestris can produce 2,6-DBP and 2,6-DCP in shelf-stable juices. Significance and Impact of the Study: This is the first report detailing experimental methodology showing that A. acidoterrestris can produce 2,6-DCP in foods. Control of storage temperatures (to <,20 °C) immediately after processing may provide an effective control measure for the fruit juice industry to prevent spoilage by A. acidoterrestris. [source] A small outbreak of listeriosis potentially linked to the consumption of imitation crab meatLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2000J.M. Farber A small outbreak of listeriosis involving two previously healthy adults occurred in Ontario. Food samples obtained from the refrigerator of the patients included imitation crab meat, canned black olives, macaroni and vegetable salad, spaghetti sauce with meatballs, mayonnaise and water. All of the samples except the water contained Listeria monocytogenes. The three most heavily contaminated samples were the imitation crab meat, the olives and the salad which contained 2·1 × 109, 1·1 × 107 and 1·3 × 106 cfu g,1, respectively. L. monocytogenes serotype 1/2b was isolated from the patients, as well as from the opened and unopened imitation crab meat. Molecular typing of the isolates by both randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) typing demonstrated the imitation crab meat and clinical strains to be indistinguishable. Challenge studies performed with a pool of L. monocytogenes strains showed that imitation crab meat, but not olives, supported growth of the organism. In this study we have shown for the first time the potential involvement of imitation crab meat in a small outbreak of listeriosis. In terms of disease prevention, temperature control is critical to prevent or reduce the growth of this foodborne pathogen. In addition, with refrigerated products having a long (> 30 d) shelf life, additional safety factors must be used to prevent the growth of foodborne pathogens such as L. monocytogenes. [source] Patterns of care and referral in children with atopic dermatitis and concern for food allergyDERMATOLOGIC THERAPY, Issue 2 2006Michele M. Thompson ABSTRACT:, Although many providers believe that up to 30% of atopic dermatitis (AD) is food induced, food challenge studies show that food-induced eczematous reactions are rare. When food allergy is suggested to cause AD, it often leads to allergy testing with a high false-positivity rate, in turn further focusing parents on food allergy. Study subjects were children less than 11 years old with AD and food allergy suspicion. Prior diagnoses, provider, and testing patterns were assessed by questionnaire given to the parents. Thirty-eight patients with AD were enrolled. Most subject's parents suspected food allergy induced AD. Initial skin diagnoses were made by pediatricians (79%) and family practitioners (18%) as eczema. Allergy was suggested by providers as cause for AD in 63% of the present study's patients. Seventy-nine percent had allergy testing. Greater than 90% of parents claimed their children had food allergy and food-induced AD. Sixty-six percent had positive food allergy tests and 37% had definite history of immediate IgE reactions to food. The majority of this population had allergy suggested as causative for eczema by their primary care provider and were subsequently evaluated by allergist and allergy testing. Consensus about the role of food allergy between the different providers of AD in children would result in more effective, efficient, and less costly health care. [source] Influenza A viruses with truncated NS1 as modified live virus vaccines: Pilot studies of safety and efficacy in horsesEQUINE VETERINARY JOURNAL, Issue 1 2009T. M. Chambers Summary Reasons for performing study: Three previously described NS1 mutant equine influenza viruses encoding carboxyterminally truncated NS1 proteins are impaired in their ability to inhibit type I IFN production in vitro and are replication attenuated, and thus are candidates for use as a modified live influenza virus vaccine in the horse. Hypothesis: One or more of these mutant viruses is safe when administered to horses, and recipient horses when challenged with wild-type influenza have reduced physiological and virological correlates of disease. Methods: Vaccination and challenge studies were done in horses, with measurement of pyrexia, clinical signs, virus shedding and systemic proinflammatory cytokines. Results: Aerosol or intranasal inoculation of horses with the viruses produced no adverse effects. Seronegative horses inoculated with the NS1-73 and NS1-126 viruses, but not the NS1-99 virus, shed detectable virus and generated significant levels of antibodies. Following challenge with wild-type influenza, horses vaccinated with NS1-126 virus did not develop fever (>38.5°C), had significantly fewer clinical signs of illness and significantly reduced quantities of virus excreted for a shorter duration post challenge compared to unvaccinated controls. Mean levels of proinflammatory cytokines IL-1, and IL-6 were significantly higher in control animals, and were positively correlated with peak viral shedding and pyrexia on Day +2 post challenge. Conclusion and clinical relevance: These data suggest that the recombinant NS1 viruses are safe and effective as modified live virus vaccines against equine influenza. This type of reverse genetics-based vaccine can be easily updated by exchanging viral surface antigens to combat the problem of antigenic drift in influenza viruses. [source] Experimental challenge studies in Vietnamese catfish, Pangasianodon hypophthalmus (Sauvage), exposed to Edwardsiella ictaluri and Aeromonas hydrophilaJOURNAL OF FISH DISEASES, Issue 9 2010M Crumlish Abstract The two main diseases in the pangasius catfish industry are bacillary necrosis of Pangasianodon (BNP) and motile aeromonas septicaemia (MAS), where the aetiological agents have been identified as Edwardsiella ictaluri and Aeromonas hydrophila, respectively. In this study, apparently healthy Pangasianodon hypophthalmus were exposed to E. ictaluri, A. hydrophila or both bacterial species by intraperitoneal injection or immersion. There were 20 fish per treatment group, and the bacterial isolates used for the study were recovered from natural infections of BNP or MAS in farmed Vietnamese P. hypophthalmus. The results of the experimental infections mimicked the natural disease outbreaks reported from these pathogens in P. hypophthalmus. Furthermore, it was clearly demonstrated that E. ictaluri was only recovered from the fish exposed to the bacterium and not recovered from the animals receiving A. hydrophila. [source] CHALLENGE STUDIES WITH PROTEOLYTIC CLOSTRIDIUM BOTULINUM IN YEAST AND CHEMICALLY LEAVENED CRUMPETS PACKAGED UNDER MODIFIED ATMOSPHERESJOURNAL OF FOOD SAFETY, Issue 2 2003DAPHNE PHILLIPS DAIFAS ABSTRACT Challenge studies were done with proteolytic Clostridium botulinum (103 spores/g) in yeast-and chemical-leavened crumpets (50-g) packaged in air with an ethanol vapor (2-G Ethicap®) generator or in 100% CO2 and stored at ambient temperature (25C) for 30 days. Neurotoxin was detected in all gas- (CO2) packaged crumpets after 5 days regardless of the method of leavening. While neurotoxin was delayed for 10 days in chemical-leavened Ethicap®-packaged crumpets, it was not detected in any similarly packaged yeast-leavened crumpets throughout storage. This inhibition of growth and neurotoxin production by C. botulinum was attributed to the production of ethanol by Saccharomyces cerevisiae in the yeast leavened crumpets, in conjunction with the ethanol vapor generated by the Ethicap® sachets (2-G), to levels to inhibitory to the growth of C. botulinum (>2.8% v/v). Subsequent challenge studies in sterile crumpets inoculated with either C. botulinum (103 spores/g) or a co-inoculum of C. botulinum (103 spores/g) and S. cerevisiae (105 CFU/g) confirmed the significant role (p<0.001) of S. cerevisiae in enhancing the antibotulinal efficacy of ethanol vapor. These studies showed that the method of crumpet leavening could have a profound effect on the growth of and neurotoxin production by C. botulinum in crumpets packaged under modified atmospheres. [source] Preclinical AIDS vaccine research: survey of SIV, SHIV, and HIV challenge studies in vaccinated nonhuman primatesJOURNAL OF MEDICAL PRIMATOLOGY, Issue 4-5 2002Jon WarrenArticle first published online: 21 AUG 200 Abstract: This current supplementary and systematic survey of 237 preclinical AIDS vaccine challenge/protection studies in nonhuman primates enumerates and broadly describes the recent status of different vaccine strategies in macaque and chimpanzee experimental models. Published studies since the previous survey were compiled and categorized by their vaccine types, challenge parameters, and challenge results. These models have supportively verified that some prophylactic vaccine approaches, though rarely preventing infection (which is observed in these models with some passively administered antibody-based vaccines), can control to some degree primate lentivirus replication and disease development, and this is encouraging because it places more potentially effective immunogens on the precipice for early clinical studies. Many of these promising approaches may benefit from more testing in mucosal challenge models, and resources will be needed to follow more of these partially protected vaccinees for longer periods. [source] Evidence for quorum sensing in Clostridium botulinum 56ALETTERS IN APPLIED MICROBIOLOGY, Issue 1 2006L. Zhao Abstract Aims:, Experiments were designed to detect quorum-sensing signals produced by Clostridium botulinum. Methods and Results:,Clostridium botulinum 56A cell-free supernatants obtained at the end of lag phase, the mid-exponential phase and early stationary phase of growth were assayed for bioluminescence in the Vibrio harveyi quorum-sensing assay system. Twelve and 16-h culture supernatants induced bioluminescence in the auto-inducer 2 (AI-2) but not the auto-inducer 1 (AI-1) assay. Intra-species quorum sensing was also assayed as the ability of the supernatants to promote spore germination and outgrowth in a microtitre plate system. Spore populations exposed to C. botulinum supernatant from the end of lag phase became positive for growth sooner than controls. Conclusions:, The influence of cell-free supernatant on ungerminated spores and detection of bioluminescence in the AI-2 assay are evidence for a signalling molecule(s) and provide a first step in characterizing C. botulinum quorum sensing. Significance and Impact of the Study:, This study suggests that spores do not behave independently of each other and may explain the inocula size effects observed in challenge studies. Whether AI-2 production in C. botulinum serves as an inter-species signal or as a detoxification mechanism remains to be determined. [source] Residual tumor cells are unique cellular targets in glioblastoma,ANNALS OF NEUROLOGY, Issue 2 2010Martin Glas MD Residual tumor cells remain beyond the margins of every glioblastoma (GBM) resection. Their resistance to postsurgical therapy is considered a major driving force of mortality, but their biology remains largely uncharacterized. In this study, residual tumor cells were derived via experimental biopsy of the resection margin after standard neurosurgery for direct comparison with samples from the routinely resected tumor tissue. In vitro analysis of proliferation, invasion, stem cell qualities, GBM-typical antigens, genotypes, and in vitro drug and irradiation challenge studies revealed these cells as unique entities. Our findings suggest a need for characterization of residual tumor cells to optimize diagnosis and treatment of GBM. ANN NEUROL 2010;68:264,269 [source] Serotonergic dysregulation in bipolar disorders: a literature review of serotonergic challenge studiesBIPOLAR DISORDERS, Issue 6 2002S Sobczak Objectives:, Serotonin (5-hydroxytryptamine; 5-HT) and endocrine abnormalities have been repeatedly reported in bipolar disorders (BD). Useful methods to investigate 5-HT responsivity, and the interaction with neuroendocrine functioning, are provided by acute 5-HT challenge and depletion paradigms. In this review 5-HT challenges are limited to paradigms that stimulate 5-HT activity in BD. Methods:, Literature was searched for in electronic libraries: MEDLINE and PSYCHLIT, period 1966,2001. Papers describing effects of an acute 5-HT challenge on neuroendocrine functioning in BD patients were selected. Results:, Review of the literature revealed 15 studies: five papers described the effects of 5-HT challenges in manic BD patients, four papers in euthymic BD and seven in depressed BD patients. The reviewed 5-HT challenge paradigms are acute administration of oral and intravenous (i.v.) dosage of d,l-fenfluramine, tryptophan, 5-hydroxytryptophan, ipsapirone and buspirone. There were no papers which investigated neuroendocrine effects of m-chlorophenylpiperazine, clomipramine and citalopram in BD patients and were therefore not reviewed. Conclusions:, The literature on 5-HT challenge procedures in BD shows evidence for a blunted prolactin (PRL) in mania and depression as well as a blunted cortisol in euthymic BD patients. This suggests that in both mania and depression similar changes in the 5-HT system are involved. It is speculated that blunting of cortisol responses in euthymic BD patients may be a result of chronically altered 5-HT functioning, whereas changes in PRL release following 5-HT challenges reflect more state-dependent changes in 5-HT activity. The 5-HT responsivity in BD patients has also been associated with pharmacological treatment, suicidal behaviour, weight loss and age. Recommendations for future research are given. [source] Enhancement of antitumor natural killer cell activation by orally administered Spirulina extract in miceCANCER SCIENCE, Issue 8 2009Yuusuke Akao Oral administration of hot-water extract of Spirulina, cyanobacterium Spirulina platensis, leads to augmentation of NK cytotoxicity in humans. Here, we applied to syngeneic tumor-implant mice (C57BL/6 versus B16 melanoma) Spirulina to elucidate the mechanism of raising antitumor NK activation. A B16D8 subcell line barely expressed MHC class I but about 50% expressed Rae-1, a ligand for NK activation receptor NKG2D. The Rae-1-positive population of implant B16 melanoma was effectively eliminated in the tumor mass progressed in mice. This antitumor activity was induced in parallel with IFN-, and abolished in mice by treatment with asialoGM-1 but not CD8, Ab, suggesting the effector is NK cell. NK cell activation occurred in the spleen of wild-type mice medicated with Spirulina. This Spirulina-mediated enhanced NK activation was abrogated in MyD88 ,/, mice but not in TICAM-1 ,/, mice. The NK activating properties of Spirulina depending on MyD88 were confirmed with in vitro bone marrow-derived dendritic cells expressing TLR2/4. In D16D8 tumor challenge studies, the antitumor effect of Spirulina was abolished in MyD88 ,/, mice. Hence, orally administered Spirulina enhances tumoricidal NK activation through the MyD88 pathway. Spirulina exerted a synergistic antitumor activity with BCG,cell wall skeleton, which is known to activate the MyD88 pathway via TLR2/4 with no NK enhancing activity. Spirulina and BCG,cell wall skeleton synergistically augmented IFN-, production and antitumor potential in the B16D8 versus C57BL/6 system. We infer from these results that NK activation by Spirulina has some advantage in combinational use with BCG,cell wall skeleton for developing adjuvant-based antitumor immunotherapy. (Cancer Sci 2009) [source] Serotonin, personality and borderline personality disorderACTA NEUROPSYCHIATRICA, Issue 2 2002M. Hansenne Serotonin is one of the neurotransmitters implicated in normal personality. Many psychobiological models of personality include some dimensions related to serotonin. For instance, the harm avoidance dimension of the biosocial model developed by Cloninger is related to serotonergic activity. Higher scores on the harm avoidance dimension should theoretically reflect increased serotonergic activity. However, correlation studies related serotonin activity to harm avoidance dimension have not yielded consistent findings. These controversial results are probably related to the complexity of the neurotransmitter systems, and the different assessment techniques used in these studies. Finally, recent genetic studies have examined the association between personality dimensions and serotonergic receptor polymorphisms with mixed results. Serotonin is not only related to some dimensions of normal personality. Several psychopathological disorders are associated with serotonergic dysfunction. More particularly, borderline personality disorder (BPD) can be defined by many of the symptoms associated with serotonergic dysregulation, including affective lability, suicidal behaviours, impulsivity and loss of impulse control. Indeed, several reports have demonstrated the efficacy of selective serotonin re-uptake drugs in treating the depressive and impulsive symptoms of patients with BPD. Moreover, some challenge studies have reported a lower serotonergic activity in BPD. Because these challenges are not specific, we have assessed the serotonergic activity in BPD with the flesinoxan challenge. Preliminary results showed that the prolactine responses to flesinoxan were significantly lower in BPD patients compared to those observed in controls. [source] | ||||||||||