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The phosphorylation on tyrosine of a protein in Escherichia coli both in vivo and in vitro was revealed by recognition by anti-phosphotyrosine antibodies, labelling with [gamma-32P]ATP, and phosphoamino acid analysis. This protein, which... more
The phosphorylation on tyrosine of a protein in Escherichia coli both in vivo and in vitro was revealed by recognition by anti-phosphotyrosine antibodies, labelling with [gamma-32P]ATP, and phosphoamino acid analysis. This protein, which we name TypA, is the product of the o591 reading frame as revealed by N-terminal sequencing and antibody cross-reactivity. Inactivation of typA altered the patterns of protein synthesis during both exponential growth and carbon starvation. These alterations included the disappearance of an acidic isoform of both the universal stress protein UspA and carbon starvation protein Csp15, and increased synthesis of the histone-like protein H-NS. The sequence of TypA from strain K-12 differs from that of an enteropathogenic strain in six amino acid residues and the protein is three residues shorter. We propose that TypA interacts with global regulatory networks and that its phosphorylation may be relevant to pathogenesis.
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Microorganisms possess the ability to recognize hormones within the host and utilize them to adapt to their surroundings. Noradrenaline and adrenaline, which are released during human stress responses, may act as environmental cues to... more
Microorganisms possess the ability to recognize hormones within the host and utilize them to adapt to their surroundings. Noradrenaline and adrenaline, which are released during human stress responses, may act as environmental cues to alter the growth of individual organisms within subgingival biofilms. The aims of this study were to modify, for anaerobic culture, existing methodology used in determining microorganism catecholamine responses and to investigate the growth responses to noradrenaline and adrenaline of 43 microorganisms found within subgingival microbial complexes. We established initial inocula for each strain using anaerobic culture, re-inoculated into a minimal serum-based medium and grown anaerobically at 35 degrees C. We assessed organism growth by optical density (OD(600nm)) readings, with test and control cultures performed in triplicate. Test cultures were supplemented with 50 microm noradrenaline or 100 microm adrenaline. We observed significant growth effects for supplementation with noradrenaline (20 species responding positively) and adrenaline (27 species responding positively), with differences in growth response observed within bacterial species and within and between microbial complexes. The most pronounced positive growth effects of noradrenaline were demonstrated in Actinomyces naeslundii (+ 49.4%), Actinomyces gerenscseriae (+ 57.2%), Eikenella corrodens (+ 143.3%) and Campylobacter gracilis (+ 79.9%). We also observed inhibitory effects of noradrenaline supplementation for Porphyromonas gingivalis (- 11.9%) and Bacteroides forsythus (- 22.2%). Responses to adrenaline tended to mirror the responses seen with noradrenaline. Individual organisms from different microbial complexes vary in their in vitro growth responses to noradrenaline and adrenaline. Such variation may influence the in vivo composition of the subgingival biofilm in response to stress-induced changes in local catecholamine levels and play a significant role in the aetiology and pathogenesis of the periodontal diseases.
Research Interests: Dentistry, Immunology, Biofilms, Medical Microbiology, Biology, and 15 moreMedicine, In Vitro, Humans, Epinephrine, Campylobacter, Bacteria, Gingiva, Anaerobic Exercise, Actinomyces, Bacterial growth, Eikenella corrodens, Biological activity, Culture Media, Aggregatibacter actinomycetemcomitans, and Fusobacterium
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Research Interests: Microbiology, Biology, Confocal Microscopy, Medicine, Streptococcus pneumoniae, and 15 moreTranscriptome, Humans, Mice, Female, Animals, Pneumonia, Coinfection, Human Respiratory Syncytial Viruses, Epithelial cells, Biological markers, Pneumolysin, Bacterial Adhesion, Respiratory Syncytial Virus Infections Industry, real time polymerase chain reaction, and Medical and Health Sciences
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Publisher Summary This chapter provides an overview of microbial endocrinology. Microbial Endocrinology is an interdisciplinary research field that represents the intersection of microbiology, endocrinology and neurophysiology. It is... more
Publisher Summary This chapter provides an overview of microbial endocrinology. Microbial Endocrinology is an interdisciplinary research field that represents the intersection of microbiology, endocrinology and neurophysiology. It is directed at providing a new paradigm to examine and understand the ability of microorganisms to interact with a host under various physical and behavioral conditions present in both health (that is. normal homeostasis) and disease. Microbial Endocrinology has been used to get a new understanding of how stress could increase the ability of small inocula of bacteria to cause disease. This chapter also provides examples of Microbial Endocrinology, its application to the clinical arena and to provide specific methodological advice as to its performance in the laboratory setting. Microbial endocrinology is constantly evolving, as the scientific and medical communities are increasingly becoming aware that neuroendocrine hormones produced by the body can influence bacterial growth and virulence, and that the more classic nutrient-centered view may need modification.
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Background: Beta-2-agonists, like salbutamol are commonly used in patients with lung disease such as cystic fibrosis where chronic infection is common. Recently salbutamol was shown to have an effect on host defence in a murine model,... more
Background: Beta-2-agonists, like salbutamol are commonly used in patients with lung disease such as cystic fibrosis where chronic infection is common. Recently salbutamol was shown to have an effect on host defence in a murine model, impairing clearance of Haemophilus influenzae from the respiratory tract [1]. To determine if salbutamol affected bacterial virulence, we investigated the effect salbutamol had on the growth and virulence of Pseudomonas aeruginosa (PA). Aim: To determine if salbutamol affects the growth, virulence and biofilm production of PA. Methods: Clinical isolates of PA were used for experiments with and without addition of salbutamol at a range of concentrations between 0.375-100 microgram/millilitre [2]. Viable colony counts and growth curve were performed to determine bacterial growth. Biofilm formation was studied using attachment crystal violet assay, light and advanced microscopy and electron microscopy using 1 cm2 endotracheal tube pieces. Results: There was no difference in the growth of PA in the presence of salbutamol. However, even at low concentrations of salbutamol (1 mcg/ml) there was a significant increase in bacterial clumping on light microscopy and increased biofilm formation on endotracheal tube sections on electron microscopy. Conclusions: Salbutamol appears to increase biofilm formation of Pseudomonas aeruginosa . This data does not imply that the use of beta-2-agonist be discouraged, but suggests that a potential role in the virulence of PA must be investigated. References: * 1. Maris et al. Respiratory Research 2006, 7:57 * 2. Atabai et al. Intensive Care Medicine 2002, 28:705–11
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BackgroundInfectious peritonitis is a clinically important condition contributing to the significant mortality and morbidity rates observed in peritoneal dialysis (PD) patients. Although some of the socioeconomic risk factors for... more
BackgroundInfectious peritonitis is a clinically important condition contributing to the significant mortality and morbidity rates observed in peritoneal dialysis (PD) patients. Although some of the socioeconomic risk factors for PD-associated peritonitis have been identified, it is still unclear why certain patients are more susceptible than others to infection.MethodsWe examined the molecular components of human peritoneal dialysate (HPD) in an attempt to identify factors that might increase patient susceptibility to infection. Characterization studies were performed on initial and follow-up dialysate samples collected from 9 renal failure patients on PD.ResultsOur in vitro data showed that peritonitis-causing bacteria grew differently in the patient dialysates. Proteomic analysis identified an association between transferrin presence and infection risk, as peritoneal transferrin was discovered to be iron-saturated, which was in marked contrast to transferrin in blood. Further, use of radioactive iron-labeled transferrin showed peritoneal transferrin could act as a direct iron source for the growth of peritonitis-causing bacteria. We also found catecholamine stress hormones noradrenaline and adrenaline were present in the dialysates and were apparently involved in enhancing the growth of the bacteria via transferrin iron provision. This suggests the iron biology status of the PD patient may be a risk factor for development of infectious peritonitisConclusionsCollectively, our study suggests transferrin and catecholamines within peritoneal dialysate may be indicators of the potential for bacterial growth in HPD and, as infection risk factors, represent possible future targets for therapeutic manipulation.
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Peritoneal dialysis (PD) may lead to infection, which could cause dialysis failure. Estimates of infectious peritonitis rate, identification of causative microbes, and infection outcomes are scarcely reported in Saudi Arabia. We conducted... more
Peritoneal dialysis (PD) may lead to infection, which could cause dialysis failure. Estimates of infectious peritonitis rate, identification of causative microbes, and infection outcomes are scarcely reported in Saudi Arabia. We conducted this study to provide epidemiological data as a geographical reference for PD-associated peritonitis. Epidemiological, microbiological, and clinical data were retrospectively collected from pediatric patients’ medical records who were on PD between 2009 and 2018. A total of 54 pediatric patients on PD were involved in the study. The median age of the patients was 3.6 years [interquartile range (IQR) 1.7–8.0]; 56% were female children. The median time spent on PD was 39.5 months (IQR 19.75–64.25), with an overall peritonitis rate of 0.52 episodes per patient-year. In terms of infection, 116 PD-associated peritonitis episodes were identified in 37 patients. There were 38 infection episodes (32.3%) due to skin microbiota, 22 (18.8%) of gut microbiota, 12 (10.2%) of environmental microbiota, three (2.6%) of polymicrobial, and 27 (23.2%) of culture negative peritonitis. There were 45 (39%) episodes of noncomplicated peritonitis and 71 (61%) complicated peritonitis episodes. The latter included 14 (19%) relapses, 45 (63%) repeated infections, and 12 (17%) catheter removals. Using multivariate analysis, the history of peritonitis [OD 7.59, 95% confidence interval (CI) 2.87–20.00] and the presence of cardiovascular disease (OD 3.24,95% CI 1.18–8.85) were independent predictors of a complicated peritonitis episode. History of infectious peritonitis and the presence of cardiovascular disease are potential predictors of complicated PD-associated peritonitis and may provide an identifier of high-risk patients.
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M icrobial endocrinology is the discipline where microbiology, endocrinology, and neurophysiology intersect. Its objective is to examine and better understand how microorganisms interact with their hosts under circumstances of both health... more
M icrobial endocrinology is the discipline where microbiology, endocrinology, and neurophysiology intersect. Its objective is to examine and better understand how microorganisms interact with their hosts under circumstances of both health and disease. A fundamental tenet is that microorganisms carry the means for sensing host hormones, which provide environmental cues that trigger growth and may lead to pathogenic processes. Indeed, bacteria respond to mammalian hormones signals as environmental cues—an evolutionary development that should not come as a surprise. For one thing, neuroendocrine hormones are not confined to vertebrates but are widely distributed in nature. For example, the neuroendocrine hormones norepinephrine and dopamine also are found among diverse other species, including bananas, potatoes, tomatoes, insects, and protozoa. Similarly, corticotropin can be isolated from Tetrahymena pyriformis, while Pseudomonas fluorescens produces a high-affinity receptor for -amino butyric acid (GABA), an inhibitory neurotransmitter from the mammalian central nervous system. This wide distribution of neuroendocrine hormones across nature means that microorganisms have had ample opportunity to encounter, recognize, and respond to these molecules as environmental signals, including by changing growth patterns and producing virulence factors.
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Research Interests: Microbiology, Chemistry, Medicine, Biological Sciences, Dopamine, and 15 moreHumans, INTENSIVE CARE, Iron, Intensive Care Unit, Bacterial growth, Catecholamine, Coagulase, Intensive Care Units, Growth Factor, Culture Media, Catecholamines, Coagulase Negative Staphylococci, opportunistic infection, Medical and Health Sciences, and Isoprenaline
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... Page 12. 64 PE Freestone and S. Sandrini (Freestone et al. ... This makes the suggestion that epinephrine is the cate-cholamine stress hormone cross-communicating with E. coli via the recently recog-nised AI-3 quorum sensing system... more
... Page 12. 64 PE Freestone and S. Sandrini (Freestone et al. ... This makes the suggestion that epinephrine is the cate-cholamine stress hormone cross-communicating with E. coli via the recently recog-nised AI-3 quorum sensing system (Sperandio et al. 2003; Clarke et al. ...
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Proteolytic cleavage of the bacterial protein toxin pneumolysin with protease K creates two fragments of 37 and 15 kDa. This paper describes the purification of these two fragments and their subsequent physical and biological... more
Proteolytic cleavage of the bacterial protein toxin pneumolysin with protease K creates two fragments of 37 and 15 kDa. This paper describes the purification of these two fragments and their subsequent physical and biological characterisation. The larger fragment is directly involved in the cytolytic mechanism of this pore‐forming protein, via membrane binding and self‐association. The smaller fragment lacks ordered structure or discernible activity.
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Regulation of the eukaryotic cell cycle involves calcium- and lipid-stimulated kinases acting on cytoskeletal structures; there are two principal reasons for supposing that the regulation of the prokaryotic cell cycle may be fundamentally... more
Regulation of the eukaryotic cell cycle involves calcium- and lipid-stimulated kinases acting on cytoskeletal structures; there are two principal reasons for supposing that the regulation of the prokaryotic cell cycle may be fundamentally the same. First, evidence for their fundamental difference is still missing and, second, evidence for prokaryotic homologues of eukaryotic cell cycle proteins is accumulating. Such proteins include those involved in calcium regulation, such as calmodulin and calcium-dependent kinases, and those involved in lipid regulation, such as protein kinase C. Proteins identified as candidates for cytoskeletal elements now include MukB, a putative contractile protein responsible for chromosome segregation, and FtsZ, the key constituent of the "cytokinetic" ring. These similarities allow the application of powerful prokaryotic model systems to one of biology's most profound, complex and urgent problems: the nature of the regulation of the eukaryotic cell cycle.
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Catecholamine stress hormones (norepinephrine, epinephrine, and dopamine) are signals that have been shown to be used as environmental cues, which affect the growth and virulence of normal microbiota as well as pathogenic bacteria. It has... more
Catecholamine stress hormones (norepinephrine, epinephrine, and dopamine) are signals that have been shown to be used as environmental cues, which affect the growth and virulence of normal microbiota as well as pathogenic bacteria. It has been reported that Escherichia coli and Salmonella use the two-component system proteins QseC and QseE to recognise catecholamines and so act as bacterial adrenergic receptors. In this study, we mutated the E. coli O157:H7 and Salmonella enterica serovar Typhimurium genes encoding QseC and QseE and found that this did not block stress hormone responsiveness in either species. Motility, biofilm formation, and analysis of virulence of the mutants using two infection models were similar to the wild-type strains. The main differences in phenotypes of the qseC and qseE mutants were responses to changes in temperature and growth in different media particularly with respect to salt, carbon, and nitrogen salt sources. In this physiological respect, it was ...
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... in my life. I love you all. Abdullah, Fahad, Kalied, Mansour, Sultan, Mohammad, Musad (my close brother), Saad (my partner in UK), Sarah, Hind, Albandari, Aljohara,Nouf, thanks for being so supportive. Finally, I would like ...
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The role of catecholamine stress hormones and inotropes in the promotion of bacterial growth, virulence and biofilm formation Fathima Farveen Casim Sahib Mohammed Sharaff Bacteria in most environments exist and grow in association with... more
The role of catecholamine stress hormones and inotropes in the promotion of bacterial growth, virulence and biofilm formation Fathima Farveen Casim Sahib Mohammed Sharaff Bacteria in most environments exist and grow in association with surfaces, leading to formation of biofilms. In the medical context, biofilms are particularly significant for human health because of their high resistance to antimicrobial and immune system attack. In the health care setting biofilms associated with indwelling devices such as intravenous catheters and endotracheal tubes is a major clinical problem. It has been shown in previous reports that catecholamine stress hormones such as epinephrine, norepinephrine and structurally similar inotrope drugs used to treat heart and kidney problems in seriously-ill patients, are able to promote growth and virulence of certain bacteria. In this thesis, the role of catecholamine inotropes and stress hormones as an environmental factor for the induction of biofilm for...
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The human body is home to trillions of micro-organisms, which are increasingly being shown to have significant effects on a variety of disease states. Evidence exists that a bidirectional communication is taking place between us and our... more
The human body is home to trillions of micro-organisms, which are increasingly being shown to have significant effects on a variety of disease states. Evidence exists that a bidirectional communication is taking place between us and our microbiome co-habitants, and that this dialogue is capable of influencing our health in a variety of ways. This review considers how host hormonal signals shape the microbiome, and what in return the microbiome residents may be signalling to their hosts.
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... Page 12. 64 PE Freestone and S. Sandrini (Freestone et al. ... This makes the suggestion that epinephrine is the cate-cholamine stress hormone cross-communicating with E. coli via the recently recog-nised AI-3 quorum sensing system... more
... Page 12. 64 PE Freestone and S. Sandrini (Freestone et al. ... This makes the suggestion that epinephrine is the cate-cholamine stress hormone cross-communicating with E. coli via the recently recog-nised AI-3 quorum sensing system (Sperandio et al. 2003; Clarke et al. ...
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Microbial Endocrinology is a new microbiology research discipline that represents the intersection of microbiology and endocrinology with neurophysiology. It has as its main tenet that through their long co-existence with animals and... more
Microbial Endocrinology is a new microbiology research discipline that represents the intersection of microbiology and endocrinology with neurophysiology. It has as its main tenet that through their long co-existence with animals and plants, micro-organisms have evolved sensory systems for detecting host-associated hormones. These sensing systems allow the microbe to determine that they are within proximity of a suitable host, and that is time to initiate expression of genes involved in host colonisation. Microbial Endocrinology therefore provides a new paradigm with which to examine and understand the interactions of micro-organisms with their host under conditions present in both health and disease. This article will focus on microbial interactions with the fight and flight family of catecholamine stress hormones.
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Psychological stress is known to increase the circulating levels of the catecholamine hormones noradrenaline and adrenaline, which have been shown to influence the growth of a large number of bacterial species by acting in a... more
Psychological stress is known to increase the circulating levels of the catecholamine hormones noradrenaline and adrenaline, which have been shown to influence the growth of a large number of bacterial species by acting in a siderophore-like manner or by inducing the production of novel autoinducers of growth. As we have previously demonstrated that periodontal organisms display differing growth responses to noradrenaline and adrenaline, the aim of this study was to determine whether these growth effects were based upon either siderophore-like or autoinducer mechanisms. Initial inocula of 43 microbial organisms normally found within the subgingival biofilm were established under anaerobic conditions (35 degrees C). Each strain was re-inoculated into a serum-based minimal medium and growth was assessed by optical density (OD(600 nm)) with test and control cultures performed in triplicate. Test cultures were supplemented with either 50 mum ferric nitrate or a previously described Escherichia coli autoinducer of growth. Significant growth effects for supplementation with ferric nitrate (13 species responding positively) and E. coli autoinducer (24 species responding positively) were observed, with differences in growth response within bacterial species and within microbial complexes. When data for all organisms were compared with published responses to catecholamines there were only weak correlations with Fe (r = 0.28) and E. coli autoinducer (r = 0.34) responses. However, large positive responses (> 25% increase) to free Fe and/or E. coli autoinducer were significantly more prevalent in the group of organisms (n = 12) known to exhibit similar responses to catecholamine hormones (P < 0.01; chi2 = 4.56). The results support the view that catecholamines may exert their effects on subgingival organisms by initiating autoinducer production, or simply by acting in a siderophore-like manner, scavenging bound iron from the local environment. It is possible that autoinducer mechanisms may play an important role in the response of oral microorganisms to stress hormones, thereby contributing to the clinical course of stress-associated periodontal diseases.
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Acquisition of iron from key innate immune defence proteins such as transferrin (Tf) and lactoferrin is an important mechanism by which pathogenic bacteria obtain essential iron for growth within their host. Bacterial species that do not... more
Acquisition of iron from key innate immune defence proteins such as transferrin (Tf) and lactoferrin is an important mechanism by which pathogenic bacteria obtain essential iron for growth within their host. Bacterial species that do not produce siderophores often use specific Tf-binding proteins, the best characterized being the Neisseriaceae-type Tf-binding proteins TbpA and TbpB. Previous work from our laboratory has shown that siderophore-producing enteric species such as Escherichia coli also readily bind Tf, although no genomic evidence exists for Tbp-like Tf-binding proteins. Application of proteomic analyses and molecular mutagenesis strategies to an enteropathogenic E. coli identified the OmpA and OmpC porins as Tf-binding proteins. Mutagenesis of the ompA or ompC genes affected E. coli Tf binding and, furthermore, compromised the ability of the ompA mutant to respond to growth promotion by certain catecholamine stress hormones. Evidence was also found to implicate the OmpA porin as an entry point for catecholamine stress hormones. Further proteomic analyses in other bacterial pathogens revealed wide-scale involvement of porins in Tf binding: Salmonella typhimurium (OmpC), and Shigella sonnei, Shigella flexneri and Shigella boydii (OmpC and/or OmpA). This study shows that in addition to their existing housekeeping functions, the Gram-negative porin family of proteins can also act as Tf-capture proteins for those bacteria that lack the classical Neisseriaceae-type Tf-binding proteins.
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In the bacterium Escherichia coli, H-NS-(H1, H1a) is a heat-stable protein with a molecular mass of 15.5 kDa involved in nucleoid organisation and gene regulation linked to certain signal transduction pathways. We have shown that,... more
In the bacterium Escherichia coli, H-NS-(H1, H1a) is a heat-stable protein with a molecular mass of 15.5 kDa involved in nucleoid organisation and gene regulation linked to certain signal transduction pathways. We have shown that, following addition of preparations of everted inner membrane vesicles, heat-stable cleavage products of approximately 10 kDa of H-NS are formed in vitro from newly synthesised, radio-labelled H-NS and from purified H-NS. The 15.5 kDa protein and its cleavage products were also recovered from a minicell system. These results raised the possibility that cleavage of H-NS is physiologically significant. However, the cleavage of H-NS observed appears to occur during cell breakage and to depend on the method of protein extraction and the presence of the outer membrane protease, OmpT. Nevertheless, the results indicate that H-NS may contain at least two separate domains with cleavage occurring between these domains at a preferred OmpT site. Failure to take account of H-NS cleavage in sample preparation and analysis can lead to serious underestimation of H-NS levels.
Research Interests: Chemistry, Gene regulation, Medicine, Sample Preparation, Escherichia coli, and 10 moreSignal Transduction Pathway Models, Artifacts, Biochimie, Molecular Mass, Sodium Dodecyl Sulphate, Polyacrylamide Gel Electrophoresis, DNA binding proteins, Biochemistry and cell biology, Phosphate Buffer Saline, and binding sites
Microorganisms possess the ability to recognize hormones within the host and utilize them to adapt to their surroundings. Noradrenaline and adrenaline, which are released during human stress responses, may act as environmental cues to... more
Microorganisms possess the ability to recognize hormones within the host and utilize them to adapt to their surroundings. Noradrenaline and adrenaline, which are released during human stress responses, may act as environmental cues to alter the growth of individual organisms within subgingival biofilms. The aims of this study were to modify, for anaerobic culture, existing methodology used in determining microorganism catecholamine responses and to investigate the growth responses to noradrenaline and adrenaline of 43 microorganisms found within subgingival microbial complexes. We established initial inocula for each strain using anaerobic culture, re-inoculated into a minimal serum-based medium and grown anaerobically at 35 degrees C. We assessed organism growth by optical density (OD(600nm)) readings, with test and control cultures performed in triplicate. Test cultures were supplemented with 50 microm noradrenaline or 100 microm adrenaline. We observed significant growth effects for supplementation with noradrenaline (20 species responding positively) and adrenaline (27 species responding positively), with differences in growth response observed within bacterial species and within and between microbial complexes. The most pronounced positive growth effects of noradrenaline were demonstrated in Actinomyces naeslundii (+ 49.4%), Actinomyces gerenscseriae (+ 57.2%), Eikenella corrodens (+ 143.3%) and Campylobacter gracilis (+ 79.9%). We also observed inhibitory effects of noradrenaline supplementation for Porphyromonas gingivalis (- 11.9%) and Bacteroides forsythus (- 22.2%). Responses to adrenaline tended to mirror the responses seen with noradrenaline. Individual organisms from different microbial complexes vary in their in vitro growth responses to noradrenaline and adrenaline. Such variation may influence the in vivo composition of the subgingival biofilm in response to stress-induced changes in local catecholamine levels and play a significant role in the aetiology and pathogenesis of the periodontal diseases.
Research Interests: Dentistry, Immunology, Biofilms, Medical Microbiology, Biology, and 15 moreMedicine, In Vitro, Humans, Epinephrine, Campylobacter, Bacteria, Norepinephrine, Gingiva, Actinomyces, Optics and Photonics, Eikenella corrodens, Biological activity, Culture Media, Aggregatibacter actinomycetemcomitans, and Fusobacterium
Microbes acquire unique lifestyles under different environmental conditions. Although this is a widespread occurrence, our knowledge of the importance of various host signals and their impact on microbial behavior is not clear despite the... more
Microbes acquire unique lifestyles under different environmental conditions. Although this is a widespread occurrence, our knowledge of the importance of various host signals and their impact on microbial behavior is not clear despite the therapeutic value of this knowledge.
Research Interests: Microbiology and Mbio
Background Infectious peritonitis is a clinically important condition contributing to the significant mortality and morbidity rates observed in peritoneal dialysis (PD) patients. Although some of the socioeconomic risk factors for... more
Background Infectious peritonitis is a clinically important condition contributing to the significant mortality and morbidity rates observed in peritoneal dialysis (PD) patients. Although some of the socioeconomic risk factors for PD-associated peritonitis have been identified, it is still unclear why certain patients are more susceptible than others to infection. Methods We examined the molecular components of human peritoneal dialysate (HPD) in an attempt to identify factors that might increase patient susceptibility to infection. Characterization studies were performed on initial and follow-up dialysate samples collected from 9 renal failure patients on PD. Results Our in vitro data showed that peritonitis-causing bacteria grew differently in the patient dialysates. Proteomic analysis identified an association between transferrin presence and infection risk, as peritoneal transferrin was discovered to be iron-saturated, which was in marked contrast to transferrin in blood. Furthe...
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Research Interests:
Research Interests:
We show in this report that traces of juices released from salad leaves as they became damaged can significantly enhance Salmonella enterica salad leaf colonisation. Salad juices in water increased Salmonella growth by 110% over the... more
We show in this report that traces of juices released from salad leaves as they became damaged can significantly enhance Salmonella enterica salad leaf colonisation. Salad juices in water increased Salmonella growth by 110% over the un-supplemented control, and in host-like serum based media by more than 2400-fold over controls. In serum based media salad juices induced growth of Salmonella via provision of Fe from transferrin, and siderophore production was found to be integral to the growth induction process. Other aspects relevant to salad leaf colonisation and retention were enhanced, such as motility and biofilm formation, which increased over controls by >220% and 250% respectively; direct attachment to salad leaves increased by >350% when a salad leaf juice was present. In terms of growth and biofilm formation the endogenous salad leaf microbiota was largely unresponsive to leaf juice, suggesting that Salmonella gains a marked advantage from fluids released from salad l...