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Julian I Rood - One of the best experts on this subject based on the ideXlab platform.
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concurrent host pathogen transcriptional responses in a clostridium perfringens murine Myonecrosis infection
Mbio, 2018Co-Authors: Paul F. Harrison, David R. Powell, Jocelyn M. Choo, Samuel C. Forster, Linden J. Gearing, Jackie K. Cheung, Paul Hertzog, Jodee A Gould, Ross L Chapman, Julian I RoodAbstract:: To obtain an insight into host-pathogen interactions in clostridial Myonecrosis, we carried out comparative transcriptome analysis of both the bacterium and the host in a murine Clostridium perfringens infection model, which is the first time that such an investigation has been conducted. Analysis of the host transcriptome from infected muscle tissues indicated that many genes were upregulated compared to the results seen with mock-infected mice. These genes were enriched for host defense pathways, including Toll-like receptor (TLR) and Nod-like receptor (NLR) signaling components. Real-time PCR confirmed that host TLR2 and NLRP3 inflammasome genes were induced in response to C. perfringens infection. Comparison of the transcriptome of C. perfringens cells from the infected tissues with that from broth cultures showed that host selective pressure induced a global change in C. perfringens gene expression. A total of 33% (923) of C. perfringens genes were differentially regulated, including 10 potential virulence genes that were upregulated relative to their expression in vitro These genes encoded putative proteins that may be involved in the synthesis of cell wall-associated macromolecules, in adhesion to host cells, or in protection from host cationic antimicrobial peptides. This report presents the first successful expression profiling of coregulated transcriptomes of bacterial and host genes during a clostridial Myonecrosis infection and provides new insights into disease pathogenesis and host-pathogen interactions.IMPORTANCEClostridium perfringens is the causative agent of traumatic clostridial Myonecrosis, or gas gangrene. In this study, we carried out transcriptional analysis of both the host and the bacterial pathogen in a mouse Myonecrosis infection. The results showed that in comparison to mock-infected control tissues, muscle tissues from C. perfringens-infected mice had a significantly altered gene expression profile. In particular, the expression of many genes involved in the innate immune system was upregulated. Comparison of the expression profiles of C. perfringens cells isolated from the infected tissues with those from equivalent broth cultures identified many potential virulence genes that were significantly upregulated in vivo These studies have provided a new understanding of the range of factors involved in host-pathogen interactions in a Myonecrosis infection.
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cross complementation of clostridium perfringens plc and clostridium septicum α toxin mutants reveals plc is sufficient to mediate gas gangrene
Microbes and Infection, 2009Co-Authors: Catherine L Kennedy, John J Emmins, Jackie K. Cheung, Dena Lyras, Thomas J Hiscox, Julian I RoodAbstract:Clostridium perfringens and Clostridium septicum are the most common causes of clostridial Myonecrosis or gas gangrene. Although they mediate a similar disease pathology, they elaborate functionally very different α-toxins. We used a reciprocal complementation approach to assess the contribution of the primary toxin of each species to disease and found that C. perfringens α-toxin (PLC) was able to mediate the gross pathology of Myonecrosis even in a C. septicum background, although it could not induce vascular leukostasis. Conversely, while C. septicum α-toxin restored some virulence to a C. perfringens plc mutant, it was less active than in its native background.
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Synergistic effects of alpha-toxin and perfringolysin O in Clostridium perfringens-mediated gas gangrene.
Infection and immunity, 2001Co-Authors: Milena M Awad, Darren M Ellemor, John J Emmins, Richard L. Boyd, Julian I RoodAbstract:To examine the synergistic effects of alpha-toxin and perfringolysin O in clostridial Myonecrosis, homologous recombination was used to construct an alpha-toxin deficient derivative of a perfringolysin O mutant of Clostridium perfringens. The subsequent strain was complemented with separate plasmids that carried the alpha-toxin structural gene (plc), the perfringolysin O gene (pfoA), or both toxin genes, and the resultant isogenic strains were examined in a mouse Myonecrosis model. Synergistic effects were clearly observed in these experiments. Infection with the control strain, which did not produce either toxin, resulted in very minimal gross pathological changes, whereas the isogenic strain that was reconstituted for both toxins produced a pathology that was clearly more severe than when alpha-toxin alone was reconstituted. These changes were most apparent in the rapid spread of the disease, the gross pathology of the footpad and in the rate at which the mice had to be euthanatized for ethical reasons. Elimination of both alpha-toxin and perfringolysin O production removed most of the histopathological features typical of clostridial Myonecrosis. These effects were restored when the mutant was complemented with the alpha-toxin structural gene, but reconstituting only perfringolysin O activity produced vastly different results, with regions of coagulative necrosis, apparently enhanced by vascular disruption, being observed. Reconstitution of both alpha-toxin and perfringolysin O activity produced histopathology most similar to that observed with the alpha-toxin reconstituted strain. The spreading of Myonecrosis was very rapid in these tissues, and coagulative necrosis appeared to be restricted to the lumen of the blood vessels. The results of these virulence experiments clearly support the hypothesis that alpha-toxin and perfringolysin O have a synergistic effect in the pathology of gas gangrene.
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use of genetically manipulated strains of clostridium perfringens reveals that both alpha toxin and theta toxin are required for vascular leukostasis to occur in experimental gas gangrene
Infection and Immunity, 1999Co-Authors: Darren M Ellemor, Rebecca N Baird, Milena M Awad, Richard L. Boyd, Julian I Rood, John J EmminsAbstract:A hallmark of gas gangrene (clostridial Myonecrosis) pathology is a paucity of leukocytes infiltrating the necrotic tissue. The cause of this paucity most likely relates to the observation of leukocyte aggregates at the border of the area of tissue necrosis, often within the microvasculature itself. Infecting mice with genetically manipulated strains of Clostridium perfringens type A (deficient in either alpha-toxin or theta-toxin production) resulted in significantly reduced leukocyte aggregation when alpha-toxin was absent and complete abrogation of leukocyte aggregation when theta-toxin was absent. Thus, both alpha-toxin and theta-toxin are necessary for the characteristic vascular leukostasis observed in clostridial Myonecrosis.
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virulence studies on chromosomal alpha toxin and theta toxin mutants constructed by allelic exchange provide genetic evidence for the essential role of alpha toxin in clostridium perfringens mediated gas gangrene
Molecular Microbiology, 1995Co-Authors: Miilena M Awad, Dennis L Stevens, Amy E Bryant, Julian I RoodAbstract:The pathogenesis of clostridial Myonecrosis, or gas gangrene, involves the growth of the anaerobic bacterium Clostridium perfringens in the infected tissues and the elaboration of numerous extracellular toxins and enzymes. The precise role of each of these toxins in tissue invasion and necrosis has not been determined. To enable genetic approaches to be used to study C. perfringens pathogenesis we developed an allelic exchange method which involved the transformation of C. perfringens cells with a suicide plasmid carrying a gene insertionally inactivated with an erythromycin-resistance determinant. The frequency with which double reciprocal crossover events were observed was increased to a workable level by increasing the amount of homologous DNA located on either side of the inactivated gene. Allelic exchange was used to isolate mutations in the chromosomal pfoA gene, which encodes an oxygen-labile haemolysin known as theta-toxin or perfringolysin O, and in the chromosomal plc gene, which encodes the alpha-toxin or phospholipase C. The resultant mutants failed to produce detectable theta-toxin or alpha-toxin activity, respectively, and could be complemented by recombinant plasmids that carried the respective wild-type genes. The resultant strains were virulence tested in a mouse Myonecrosis model. The results showed that the plc mutants had demonstrably reduced virulence and therefore provided definitive genetic evidence for the essential role of alpha-toxin in gas gangrene or clostridial Myonecrosis.
John J Emmins - One of the best experts on this subject based on the ideXlab platform.
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cross complementation of clostridium perfringens plc and clostridium septicum α toxin mutants reveals plc is sufficient to mediate gas gangrene
Microbes and Infection, 2009Co-Authors: Catherine L Kennedy, John J Emmins, Jackie K. Cheung, Dena Lyras, Thomas J Hiscox, Julian I RoodAbstract:Clostridium perfringens and Clostridium septicum are the most common causes of clostridial Myonecrosis or gas gangrene. Although they mediate a similar disease pathology, they elaborate functionally very different α-toxins. We used a reciprocal complementation approach to assess the contribution of the primary toxin of each species to disease and found that C. perfringens α-toxin (PLC) was able to mediate the gross pathology of Myonecrosis even in a C. septicum background, although it could not induce vascular leukostasis. Conversely, while C. septicum α-toxin restored some virulence to a C. perfringens plc mutant, it was less active than in its native background.
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Synergistic effects of alpha-toxin and perfringolysin O in Clostridium perfringens-mediated gas gangrene.
Infection and immunity, 2001Co-Authors: Milena M Awad, Darren M Ellemor, John J Emmins, Richard L. Boyd, Julian I RoodAbstract:To examine the synergistic effects of alpha-toxin and perfringolysin O in clostridial Myonecrosis, homologous recombination was used to construct an alpha-toxin deficient derivative of a perfringolysin O mutant of Clostridium perfringens. The subsequent strain was complemented with separate plasmids that carried the alpha-toxin structural gene (plc), the perfringolysin O gene (pfoA), or both toxin genes, and the resultant isogenic strains were examined in a mouse Myonecrosis model. Synergistic effects were clearly observed in these experiments. Infection with the control strain, which did not produce either toxin, resulted in very minimal gross pathological changes, whereas the isogenic strain that was reconstituted for both toxins produced a pathology that was clearly more severe than when alpha-toxin alone was reconstituted. These changes were most apparent in the rapid spread of the disease, the gross pathology of the footpad and in the rate at which the mice had to be euthanatized for ethical reasons. Elimination of both alpha-toxin and perfringolysin O production removed most of the histopathological features typical of clostridial Myonecrosis. These effects were restored when the mutant was complemented with the alpha-toxin structural gene, but reconstituting only perfringolysin O activity produced vastly different results, with regions of coagulative necrosis, apparently enhanced by vascular disruption, being observed. Reconstitution of both alpha-toxin and perfringolysin O activity produced histopathology most similar to that observed with the alpha-toxin reconstituted strain. The spreading of Myonecrosis was very rapid in these tissues, and coagulative necrosis appeared to be restricted to the lumen of the blood vessels. The results of these virulence experiments clearly support the hypothesis that alpha-toxin and perfringolysin O have a synergistic effect in the pathology of gas gangrene.
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use of genetically manipulated strains of clostridium perfringens reveals that both alpha toxin and theta toxin are required for vascular leukostasis to occur in experimental gas gangrene
Infection and Immunity, 1999Co-Authors: Darren M Ellemor, Rebecca N Baird, Milena M Awad, Richard L. Boyd, Julian I Rood, John J EmminsAbstract:A hallmark of gas gangrene (clostridial Myonecrosis) pathology is a paucity of leukocytes infiltrating the necrotic tissue. The cause of this paucity most likely relates to the observation of leukocyte aggregates at the border of the area of tissue necrosis, often within the microvasculature itself. Infecting mice with genetically manipulated strains of Clostridium perfringens type A (deficient in either alpha-toxin or theta-toxin production) resulted in significantly reduced leukocyte aggregation when alpha-toxin was absent and complete abrogation of leukocyte aggregation when theta-toxin was absent. Thus, both alpha-toxin and theta-toxin are necessary for the characteristic vascular leukostasis observed in clostridial Myonecrosis.
Dennis L Stevens - One of the best experts on this subject based on the ideXlab platform.
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group a streptococcal Myonecrosis increased vimentin expression after skeletal muscle injury mediates the binding of streptococcus pyogenes
The Journal of Infectious Diseases, 2006Co-Authors: Amy E Bryant, Clifford R Bayer, Jeremy D Huntington, Dennis L StevensAbstract:Necrotizing fasciitis and Myonecrosis caused by invasive infection with group A streptococci (GAS) are life-threatening conditions that have reemerged worldwide. Half of all GAS Myonecrosis cases have no known portal of entry; yet, for unknown reasons, infection becomes established precisely at the site of a prior, nonpenetrating minor injury, such as a muscle strain. We hypothesized that GAS establishes infection by binding to surface molecules that are up-regulated on injured skeletal-muscle cells. Here, we isolated and identified vimentin as the major skeletal-muscle GAS-binding protein. Furthermore, we found that vimentin expression was up-regulated on injured skeletal-muscle cells in vitro and was expressed in muscle tissues from a patient with GAS Myonecrosis who died of streptococcal toxic shock syndrome. These findings provide a molecular mechanism to explain the development of severe GAS soft-tissue infections at the sites of prior minor muscle trauma. This understanding may provide a basis for novel preventive strategies or therapies for patients with this devastating infection.
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the pathogenesis of clostridial Myonecrosis
International Journal of Medical Microbiology, 2000Co-Authors: Dennis L StevensAbstract:These pieces of evidence can be assimilated into a molecular and cellular model of pathogenesis which is initiated by direct toxin effects upon venous capillary endothelial cell function, leading to expression of pro-inflammatory mediators and adhesion molecules, and initiation of platelet aggregation. Toxin-induced hyperadhesion of leukocytes (see above section) with enhanced respiratory burst activity (due to toxins directly or to toxin-induced IL-8 or PAF synthesis by host cells) and toxin-induced chemotaxis deficits could result in neutrophil-mediated vascular injury. Direct toxin-induced cytopathic effects on EC may also contribute to vascular abnormalities associated with gas gangrene. Over prolonged incubation periods, PLC at sublytic concentrations causes EC to undergo profound shape changes similar to those described following prolonged TNF or interferon gamma exposure. In vivo, conversion of EC to this fibroblastoid morphology could contribute to the localized vascular leakage and massive swelling observed clinically with this infection. Similarly, the direct cytotoxicity of PFO could disrupt endothelial integrity and contribute to progressive edema both locally and systemically. Thus, via the mechanisms outlined above, both PLC and PFO may cause local, regional and systemic vascular dysfunction. For instance, local absorption of exotoxins within the capillary beds could affect the physiological function of the endothelium lining the postcapillary venules, resulting in impairment of phagocyte delivery at the site of infection. Toxin-induced endothelial dysfunction and microvascular injury could also cause loss of albumin, electrolytes, and water into the interstitial space resulting in marked localized edema. These events, combined with intravascular platelet aggregation and leukostasis, would increase venous pressures and favor further loss of fluid and protein in the distal capillary bed. Ultimately, a reduced arteriolar flow would impair oxygen delivery thereby attenuating phagocyte oxidative killing and facilitating anaerobic glycolysis of muscle tissue. The resultant drop in tissue pH, together with reduced oxygen tension, might further decrease the redox potential of viable tissues to a point suitable for growth of this anaerobic bacillus. As infection progresses and additional toxin is absorbed, larger venous channels would become affected, causing regional vascular compromise, increased compartment pressures and rapid anoxic necrosis of large muscle groups. When toxins reach arterial circulation, systemic shock and multiorgan failure rapidly ensue, and death is common.
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virulence studies on chromosomal alpha toxin and theta toxin mutants constructed by allelic exchange provide genetic evidence for the essential role of alpha toxin in clostridium perfringens mediated gas gangrene
Molecular Microbiology, 1995Co-Authors: Miilena M Awad, Dennis L Stevens, Amy E Bryant, Julian I RoodAbstract:The pathogenesis of clostridial Myonecrosis, or gas gangrene, involves the growth of the anaerobic bacterium Clostridium perfringens in the infected tissues and the elaboration of numerous extracellular toxins and enzymes. The precise role of each of these toxins in tissue invasion and necrosis has not been determined. To enable genetic approaches to be used to study C. perfringens pathogenesis we developed an allelic exchange method which involved the transformation of C. perfringens cells with a suicide plasmid carrying a gene insertionally inactivated with an erythromycin-resistance determinant. The frequency with which double reciprocal crossover events were observed was increased to a workable level by increasing the amount of homologous DNA located on either side of the inactivated gene. Allelic exchange was used to isolate mutations in the chromosomal pfoA gene, which encodes an oxygen-labile haemolysin known as theta-toxin or perfringolysin O, and in the chromosomal plc gene, which encodes the alpha-toxin or phospholipase C. The resultant mutants failed to produce detectable theta-toxin or alpha-toxin activity, respectively, and could be complemented by recombinant plasmids that carried the respective wild-type genes. The resultant strains were virulence tested in a mouse Myonecrosis model. The results showed that the plc mutants had demonstrably reduced virulence and therefore provided definitive genetic evidence for the essential role of alpha-toxin in gas gangrene or clostridial Myonecrosis.
Arvind Von Keudell - One of the best experts on this subject based on the ideXlab platform.
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Factors associated with Myonecrosis at time of fasciotomy in acute leg compartment syndrome.
European journal of orthopaedic surgery & traumatology : orthopedie traumatologie, 2020Co-Authors: Dafang Zhang, Stein J. Janssen, Matthew Tarabochia, Arvind Von KeudellAbstract:Introduction: The objective of this study is to determine factors associated with Myonecrosis at the time of fasciotomy in patients with acute leg compartment syndrome. Methods: A retrospective cohort study was conducted of 546 patients with acute leg compartment syndrome treated with fasciotomies from January 2000 to June 2015 at two tertiary trauma centers. The main outcome measurement was clinical Myonecrosis diagnosed by the treating surgeon at the time of fasciotomy. Results: Eighty-two patients (15.0%) with acute leg compartment syndrome had Myonecrosis at time of fasciotomy. Multivariable logistic regression analyses showed that younger age (p = 0.004) and diabetes mellitus (p < 0.001) were associated with Myonecrosis at time of fasciotomy in acute leg compartment syndrome. Serum creatine kinase at presentation greater than 2405 U/L was found to be associated with Myonecrosis at time of fasciotomy in post hoc analysis (p < 0.001). Conclusions: Myonecrosis is associated with patient-related factors. Younger age by 10 years is associated with a 1.3 times increase and diabetes mellitus with a 3-time increase in the odds of Myonecrosis. Serum creatine kinase at presentation greater than 2405 U/L denotes an almost 3 times increase in odds of Myonecrosis and may be useful for preoperative counseling.
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factors associated with Myonecrosis at time of fasciotomy in acute leg compartment syndrome
European Journal of Orthopaedic Surgery and Traumatology, 2020Co-Authors: Dafang Zhang, Stein J. Janssen, Matthew Tarabochia, Arvind Von KeudellAbstract:The objective of this study is to determine factors associated with Myonecrosis at the time of fasciotomy in patients with acute leg compartment syndrome. A retrospective cohort study was conducted of 546 patients with acute leg compartment syndrome treated with fasciotomies from January 2000 to June 2015 at two tertiary trauma centers. The main outcome measurement was clinical Myonecrosis diagnosed by the treating surgeon at the time of fasciotomy. Eighty-two patients (15.0%) with acute leg compartment syndrome had Myonecrosis at time of fasciotomy. Multivariable logistic regression analyses showed that younger age (p = 0.004) and diabetes mellitus (p < 0.001) were associated with Myonecrosis at time of fasciotomy in acute leg compartment syndrome. Serum creatine kinase at presentation greater than 2405 U/L was found to be associated with Myonecrosis at time of fasciotomy in post hoc analysis (p < 0.001). Myonecrosis is associated with patient-related factors. Younger age by 10 years is associated with a 1.3 times increase and diabetes mellitus with a 3-time increase in the odds of Myonecrosis. Serum creatine kinase at presentation greater than 2405 U/L denotes an almost 3 times increase in odds of Myonecrosis and may be useful for preoperative counseling.
Dafang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Factors associated with Myonecrosis at time of fasciotomy in acute leg compartment syndrome.
European journal of orthopaedic surgery & traumatology : orthopedie traumatologie, 2020Co-Authors: Dafang Zhang, Stein J. Janssen, Matthew Tarabochia, Arvind Von KeudellAbstract:Introduction: The objective of this study is to determine factors associated with Myonecrosis at the time of fasciotomy in patients with acute leg compartment syndrome. Methods: A retrospective cohort study was conducted of 546 patients with acute leg compartment syndrome treated with fasciotomies from January 2000 to June 2015 at two tertiary trauma centers. The main outcome measurement was clinical Myonecrosis diagnosed by the treating surgeon at the time of fasciotomy. Results: Eighty-two patients (15.0%) with acute leg compartment syndrome had Myonecrosis at time of fasciotomy. Multivariable logistic regression analyses showed that younger age (p = 0.004) and diabetes mellitus (p < 0.001) were associated with Myonecrosis at time of fasciotomy in acute leg compartment syndrome. Serum creatine kinase at presentation greater than 2405 U/L was found to be associated with Myonecrosis at time of fasciotomy in post hoc analysis (p < 0.001). Conclusions: Myonecrosis is associated with patient-related factors. Younger age by 10 years is associated with a 1.3 times increase and diabetes mellitus with a 3-time increase in the odds of Myonecrosis. Serum creatine kinase at presentation greater than 2405 U/L denotes an almost 3 times increase in odds of Myonecrosis and may be useful for preoperative counseling.
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factors associated with Myonecrosis at time of fasciotomy in acute leg compartment syndrome
European Journal of Orthopaedic Surgery and Traumatology, 2020Co-Authors: Dafang Zhang, Stein J. Janssen, Matthew Tarabochia, Arvind Von KeudellAbstract:The objective of this study is to determine factors associated with Myonecrosis at the time of fasciotomy in patients with acute leg compartment syndrome. A retrospective cohort study was conducted of 546 patients with acute leg compartment syndrome treated with fasciotomies from January 2000 to June 2015 at two tertiary trauma centers. The main outcome measurement was clinical Myonecrosis diagnosed by the treating surgeon at the time of fasciotomy. Eighty-two patients (15.0%) with acute leg compartment syndrome had Myonecrosis at time of fasciotomy. Multivariable logistic regression analyses showed that younger age (p = 0.004) and diabetes mellitus (p < 0.001) were associated with Myonecrosis at time of fasciotomy in acute leg compartment syndrome. Serum creatine kinase at presentation greater than 2405 U/L was found to be associated with Myonecrosis at time of fasciotomy in post hoc analysis (p < 0.001). Myonecrosis is associated with patient-related factors. Younger age by 10 years is associated with a 1.3 times increase and diabetes mellitus with a 3-time increase in the odds of Myonecrosis. Serum creatine kinase at presentation greater than 2405 U/L denotes an almost 3 times increase in odds of Myonecrosis and may be useful for preoperative counseling.
