| 1. |
- Thomas, HS, et al.
(författare)
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- 2019
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swepub:Mat__t
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| 2. |
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| 3. |
- Drake, TM, et al.
(författare)
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Surgical site infection after gastrointestinal surgery in children: an international, multicentre, prospective cohort study
- 2020
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Ingår i: BMJ global health. - : BMJ. - 2059-7908. ; 5:12
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Tidskriftsartikel (refereegranskat)abstract
- Surgical site infection (SSI) is one of the most common healthcare-associated infections (HAIs). However, there is a lack of data available about SSI in children worldwide, especially from low-income and middle-income countries. This study aimed to estimate the incidence of SSI in children and associations between SSI and morbidity across human development settings.MethodsA multicentre, international, prospective, validated cohort study of children aged under 16 years undergoing clean-contaminated, contaminated or dirty gastrointestinal surgery. Any hospital in the world providing paediatric surgery was eligible to contribute data between January and July 2016. The primary outcome was the incidence of SSI by 30 days. Relationships between explanatory variables and SSI were examined using multilevel logistic regression. Countries were stratified into high development, middle development and low development groups using the United Nations Human Development Index (HDI).ResultsOf 1159 children across 181 hospitals in 51 countries, 523 (45·1%) children were from high HDI, 397 (34·2%) from middle HDI and 239 (20·6%) from low HDI countries. The 30-day SSI rate was 6.3% (33/523) in high HDI, 12·8% (51/397) in middle HDI and 24·7% (59/239) in low HDI countries. SSI was associated with higher incidence of 30-day mortality, intervention, organ-space infection and other HAIs, with the highest rates seen in low HDI countries. Median length of stay in patients who had an SSI was longer (7.0 days), compared with 3.0 days in patients who did not have an SSI. Use of laparoscopy was associated with significantly lower SSI rates, even after accounting for HDI.ConclusionThe odds of SSI in children is nearly four times greater in low HDI compared with high HDI countries. Policies to reduce SSI should be prioritised as part of the wider global agenda.
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| 4. |
- Amer, Ayad, 1980-, et al.
(författare)
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Genetically engineered frameshifted YopN-TyeA chimeras influence type III secretion system function in Yersinia pseudotuberculosis
- 2013
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Ingår i: PLOS ONE. - San Francisco : Public Library of Science. - 1932-6203. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- Type III secretion is a tightly controlled virulence mechanism utilized by many gram negative bacteria to colonize their eukaryotic hosts. To infect their host, human pathogenic Yersinia spp. translocate protein toxins into the host cell cytosol through a preassembled Ysc-Yop type III secretion device. Several of the Ysc-Yop components are known for their roles in controlling substrate secretion and translocation. Particularly important in this role is the YopN and TyeA heterodimer. In this study, we confirm that Y. pseudotuberculosis naturally produce a 42 kDa YopN-TyeA hybrid protein as a result of a +1 frame shift near the 3 prime of yopN mRNA, as has been previously reported for the closely related Y. pestis. To assess the biological role of this YopN-TyeA hybrid in T3SS by Y. pseudotuberculosis, we used in cis site-directed mutagenesis to engineer bacteria to either produce predominately the YopN-TyeA hybrid by introducing +1 frame shifts to yopN after codon 278 or 287, or to produce only singular YopN and TyeA polypeptides by introducing yopN sequence from Y. enterocolitica, which is known not to produce the hybrid. Significantly, the engineered 42 kDa YopN-TyeA fusions were abundantly produced, stable, and were efficiently secreted by bacteria in vitro. Moreover, these bacteria could all maintain functionally competent needle structures and controlled Yops secretion in vitro. In the presence of host cells however, bacteria producing the most genetically altered hybrids (+1 frameshift after 278 codon) had diminished control of polarized Yop translocation. This corresponded to significant attenuation in competitive survival assays in orally infected mice, although not at all to the same extent as Yersinia lacking both YopN and TyeA proteins. Based on these studies with engineered polypeptides, most likely a naturally occurring YopN-TyeA hybrid protein has the potential to influence T3S control and activity when produced during Yersinia-host cell contact.
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| 5. |
- Costa, Tiago, et al.
(författare)
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Measurement of Yersinia translocon pore formation in erythrocytes
- 2019
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Ingår i: Pathogenic Yersinia. - New York, NY, U.S.A. : Humana Press. - 9781493995400 ; , s. 211-229
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Bokkapitel (refereegranskat)abstract
- Many Gram-negative pathogens produce a type III secretion system capable of intoxicating eukaryotic cells with immune-modulating effector proteins. Fundamental to this injection process is the prior secretion of two translocator proteins destined for injectisome translocon pore assembly within the host cell plasma membrane. It is through this pore that effectors are believed to travel to gain access to the host cell interior. Yersinia species especially pathogenic to humans and animals assemble this translocon pore utilizing two hydrophobic translocator proteins-YopB and YopD. Although a full molecular understanding of the biogenesis, function and regulation of this translocon pore and subsequent effector delivery into host cells remains elusive, some of what we know about these processes can be attributed to studies of bacterial infections of erythrocytes. Herein we describe the methodology of erythrocyte infections by Yersinia, and how analysis of the resultant contact-dependent hemolysis can serve as a relative measurement of YopB- and YopD-dependent translocon pore formation.
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| 6. |
- Costa, Tiago R. D., et al.
(författare)
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Active type III translocon assemblies that attenuate Yersinia virulence
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Type III secretion enables bacteria to intoxicate eukaryotic cells with anti-host effectors. A class of secreted cargo are the two hydrophobic translocators that form a translocon pore in the host cell plasma membrane through which the translocated effectors may gain cellular entry. In pathogenic Yersinia, YopB and YopD shape this translocon pore. Here, four in cis yopD mutations were constructed to disrupt a predicted a-helix motif at the C-terminus. Mutants YopDI262P and YopDK267P poorly localised Yop effectors into target eukaryotic cells and failed to resist uptake and killing by immune cells. These defects were due to deficiencies in host-membrane insertion of the YopD-YopB translocon. Mutants YopDA263P and YopDA270P had no measurable in vitro translocation defect, even though they formed smaller translocon pores in erythrocyte membranes. Despite this, all four mutants were attenuated in a mouse infection model. Hence, YopD variants have been generated that can spawn translocons capable of targeting effectors in vitro, yet were bereft of any lethal effect in vivo. It is therefore probable that an active translocon makes a range of contributions during bacteria-host cell contact that extends beyond effector delivery per se.
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| 7. |
- Costa, Tiago, et al.
(författare)
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Type III secretion translocon assemblies that attenuate Yersinia virulence
- 2013
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Ingår i: Cellular Microbiology. - : Wiley-Blackwell. - 1462-5814 .- 1462-5822. ; 15:7, s. 1088-1110
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Tidskriftsartikel (refereegranskat)abstract
- Type III secretion enables bacteria to intoxicate eukaryotic cells with anti-host effectors. A class of secreted cargo are the two hydrophobic translocators that form a translocon pore in the host cell plasma membrane through which the translocated effectors may gain cellular entry. In pathogenic Yersinia, YopB and YopD shape this translocon pore. Here, four in cis yopD mutations were constructed to disrupt a predicted α-helix motif at the C-terminus. Mutants YopD(I262P) and YopD(K267P) poorly localized Yop effectors into target eukaryotic cells and failed to resist uptake and killing by immune cells. These defects were due to deficiencies in host-membrane insertion of the YopD-YopB translocon. Mutants YopD(A263P) and YopD(A270P) had no measurable in vitro translocation defect, even though they formed smaller translocon pores in erythrocyte membranes. Despite this, all four mutants were attenuated in a mouse infection model. Hence, YopD variants have been generated that can spawn translocons capable of targeting effectors in vitro, yet were bereft of any lethal effect in vivo. Therefore, Yop translocators may possess other in vivo functions that extend beyond being a portal for effector delivery into host cells.
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| 8. |
- El-Seedi, Hesham, et al.
(författare)
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Analysis of the essential oil from the aerial parts of Psoralea pubescence (Miq.) Standl and its antibacterial activity
- 2010
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Ingår i: Medicinal Chemistry Research. - : Springer Science and Business Media LLC. - 1054-2523 .- 1554-8120. ; 19:9, s. 1036-1042
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Tidskriftsartikel (refereegranskat)abstract
- The essential oil from aerial parts of Psoralea pubescence (Miq.) Standl (Leguminoseae) was analyzed by gas chromatography (GC) and GC/mass spectroscopy systems. The major components identified were psoralen (24.8%), bakuchiol (21.3%), beta-caryophyllene (8.5%), germacrene D (6.8%), and alpha-humulene (4.6%). The major volatiles released by beta-glucosidase treatment of the aqueous plant residue were delta-pinene (28.3%), germacrene D (13.6%), and tricyclene (10.2%). The oil showed significant antibacterial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa, while the beta-glucosidase-liberated fraction was inactive.
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| 9. |
- Farag, Salah I., 1959-
(författare)
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Biogenesis, function and regulation of the type III secretion translocon of Yersinia pseudotuberculosis
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many Gram negative bacteria use type III secretion systems to cross-talk with eukaryotic cells. Type III secretion system assembly and function is tightly regulated. It initiates with assembly of a basal body-like structure, and is followed by a cytoplasmic-located substrate sorting and export platform that first engages with early substrates required for needle assembly. At the needle tip, a translocon is formed upon eukaryotic cell contact to allow the translocation of effector proteins to the host cell. The focus of this thesis is on understanding aspects of biogenesis, regulation and function of the translocon and its interaction with the host cell. Research questions are addressed in enteropathogenic Yersinia pseudotuberculosis model.Prioritising the secretion of translocon components before effector proteins is a task given partly to the InvE/MxiC/HrpJ family of proteins. In Yersinia, homology to this protein family is partitioned over two proteins; YopN and TyeA. Certain Yersinia strains naturally produce a single YopN/TyeA polypeptide hybrid. To understand the implications of hybrid formation towards type III secretion control, a series of mutants were engineered to produce only a single hybrid peptide. Using in vitro assays revealed no difference in substrate secretion profiles between parent and mutants. Moreover, no obvious prioritisation of secretion between translocator and effector substrates was observed. Although these in vitro studies indicate that the YopN-TyeA single polypeptide is fully functionally competent, these mutants were attenuated in the mouse infection model. Hence, natural production of YopN and TyeA as a single polypeptide alone is unlikely to confer a fitness advantage to the infecting bacteria and is unlikely to orchestrate hierarchal substrate secretion.The YopB and YopD translocon components form a pore in the host cell plasma membrane to deliver the effectors into the host cell. To better understand how YopD contributes to the biogenesis, function and regulation of the translocon pore, a series of mutants were constructed to disrupt two predicted α-helix motifs, one lying at the N-terminus and the other at the C-terminus. Based upon phenotypes associated with environmental control of Yop synthesis and secretion, effector translocation, evasion of phagocytosis, killing of immune cells and virulence in a mouse infection model, the mutants were grouped into three phenotypic classes. A particularly interesting mutant class maintained full T3SS function in vitro, but were attenuated for virulence in a murine oral-infection model. To better understand the molecular basis for these phenotypic differences, the effectiveness of RAW 264.7 cells to respond to infection by these mutants was scrutinised. Sixteen individual cytokines were profiled with mouse cytokine screen multiplex analysis. Signature cytokine profiles were observed that could again separate the different YopD mutants into distinct categories. The activation and supression of certain cytokines that function as central innate immune response modulators correlated well with the ability of mutant bacteria to modulate programmed cell death and antiphagocytosis pathways. Hence, the biogenesis of sub-optimal translocon pores alters host cell responsiveness and limits the ability of Yersinia to fortify against attack by both early and late arms of the host innate immune response.The amount of bacteria now resistant to multiple antibiotics is alarming. By providing insights into a common virulence process, this work may ultimately facilitate the design of novel broad-acting inhibitors of type III secretion, and thereby be useful to treat an array of bacterial infections.
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| 10. |
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| 11. |
- Farag, Salah, et al.
(författare)
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Macrophage innate immune responses delineate between defective translocon assemblies produced by Yersinia pseudotuberculosis YopD mutants
- 2023
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Ingår i: Virulence. - London : Taylor & Francis Group. - 2150-5594 .- 2150-5608. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Translocon pores formed in the eukaryotic cell membrane by a type III secretion system facilitate the translocation of immune-modulatory effector proteins into the host cell interior. The YopB and YopD proteins produced and secreted by pathogenic Yersinia spp. harboring a virulence plasmid-encoded type III secretion system perform this pore-forming translocator function. We had previously characterized in vitro T3SS function and in vivo pathogenicity of a number of strains encoding sited-directed point mutations in yopD. This resulted in the classification of mutants into three different classes based upon the severity of the phenotypic defects. To investigate the molecular and functional basis for these defects, we explored the effectiveness of RAW 264.7 cell line to respond to infection by representative YopD mutants of all three classes. Signature cytokine profiles could separate the different YopD mutants into distinct categories. The activation and suppression of certain cytokines that function as central innate immune response modulators correlated well with the ability of mutant bacteria to alter anti-phagocytosis and programmed cell death pathways. These analyses demonstrated that sub-optimal translocon pores impact the extent and magnitude of host cell responsiveness, and this limits the capacity of pathogenic Yersinia spp. to fortify against attack by both early and late arms of the host innate immune response.
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| 12. |
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| 13. |
- Abbafati, Cristiana, et al.
(författare)
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- 2020
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Tidskriftsartikel (refereegranskat)
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