| 1. |
- Hakansson, HO, et al.
(author)
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Synthesis and localization of pancreatic secretory proteins in pancreatic acinar-like metaplasia in the distal part of the oesophagus
- 2003
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In: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 38:1, s. 41560-41560
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Journal article (peer-reviewed)abstract
- Background: Pancreatic acinar-like metaplasia has previously been described in the gastric mucosa and in the distal part of the oesophagus. The resemblance to pancreatic acinar cells prompted us to study the possible occurrence of secretory pancreatic proteins in these cells. Methods: Seven specimens obtained from the distal oesophagus at gastroscopy where routine microscopy showed pancreatic acinar-like metaplasia were selected for this study. Sections were subjected to immunohistochemical detection of trypsinogen, pancreatic elastase, procarboxypeptidase B and pancreatic secretory trypsin inhibitor using specific antisera. An alkaline-phosphatase-conjugated oligodeoxynucleotide probe, complementary to the transcript for trypsinogen 2 (anionic) was used for in situ hybridization. Results: Cells with pancreatic acinar-like metaplasia were immunoreactive to all pancreatic secretory proteins studied. In situ hybridization showed the presence of trypsinogen 2 mRNA in pancreatic acinar-like metaplasia. The pancreatic proteins were not seen in other cells in the distal oesophagus. Conclusion: Pancreatic acinar-like metaplasia is common in the distal oesophagus and pancreatic secretory proteins, including trypsininogen 2, are produced in the oesophageal metaplastic acinar cells. The biological significance of this finding has yet not been thoroughly studied.
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| 2. |
- Roche-Hakansson, Hazeline, et al.
(author)
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The human milk protein-lipid complex HAMLET disrupts glycolysis and induces death in Streptococcus pneumoniae
- 2019
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In: Journal of Biological Chemistry. - 1083-351X. ; 294:51, s. 19511-19522
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Journal article (peer-reviewed)abstract
- HAMLET is a complex of human a-lactalbumin (ALA) and oleic acid and kills several Gram-positive bacteria by a mechanism that bears resemblance to apoptosis in eukaryotic cells. To identify HAMLET's bacterial targets, here we used Streptococcus pneumoniae as a model organism and employed a proteomic approach that identified several potential candidates. Two of these targets were the glycolytic enzymes fructose bis-phosphate aldolase (FBPA) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Treatment of pneumococci with HAMLET immediately inhibited their ATP and lactate production, suggesting that HAMLET inhibits glycolysis. This observation was supported by experiments with recombinant bacterial enzymes, along with biochemical and bacterial viability assays, indicating that HAMLET's activity is partially inhibited by high glucose-mediated stimulation of glycolysis but enhanced in the presence of the glycolysis inhibitor 2-deoxyglucose. Both HAMLET and ALA bound directly to each glycolytic enzyme in solution and solid phase assays and effectively inhibited their enzymatic activities. In contrast, oleic acid alone had little to no inhibitory activity. However, ALA alone also exhibited no bactericidal activity and did not block glycolysis in whole cells, suggesting a role for the lipid moiety in the internalization of HAMLET into the bacterial cells to reach its target(s). This was verified by inhibition of enzyme activity in whole cells after HAMLET but not ALA exposure. The results of this study suggest that part of HAMLET's antibacterial activity relates to its ability to target and inhibit glycolytic enzymes, providing an example of a natural antimicrobial agent that specifically targets glycolysis.
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| 3. |
- Tyx, Robert E, et al.
(author)
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Role of dihydrolipoamide dehydrogenase in regulation of raffinose transport in Streptococcus pneumoniae
- 2011
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In: Journal of Bacteriology. - 0021-9193. ; 193:14, s. 24-3512
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Journal article (peer-reviewed)abstract
- Streptococcus pneumoniae strains lacking the enzyme dihydrolipoamide dehydrogenase (DLDH) show markedly reduced ability to grow on raffinose and stachyose as sole carbon sources. Import of these sugars occurs through the previously characterized raffinose ATP-binding cassette (ABC) transport system, encoded by the raf operon, that lacks the necessary ATP-binding protein. In this study, we identified the raffinose ATP-binding protein RafK and showed that it was directly involved in raffinose and stachyose import. RafK carries a C-terminal regulatory domain present in a subset of ATP-binding proteins that has been involved in both direct regulation of transporter activity (inducer exclusion) and transcription of transporter genes. Pneumococci lacking RafK showed a 50- to 80-fold reduction in expression of the raf operon genes aga (alpha-galactosidase) and rafEFG (raffinose substrate binding and permease genes), and both glucose and sucrose inhibited raffinose uptake through inducer exclusion. Like RafK, the presence of DLDH also activated the expression of raf operon genes, as DLDH-negative pneumococci showed a significantly decreased expression of aga and rafEFG, but DLDH did not regulate rafK or the putative regulatory genes rafR and rafS. DLDH also bound directly to RafK both in vitro and in vivo, indicating the possibility that DLDH regulates raffinose transport by a direct interaction with the regulatory domain of the transporter. Finally, although not as attenuated as DLDH-negative bacteria, pneumococci lacking RafK were significantly outcompeted by wild-type bacteria in colonization experiments of murine lung and nasopharynx, indicating a role for raffinose and stachyose transport in vivo.
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| 4. |
- Alamiri, Feiruz, et al.
(author)
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A role of epithelial cells and virulence factors in biofilm formation by Streptococcus pyogenes in vitro
- 2020
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In: Infection and Immunity. - 1098-5522. ; 88:10
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Journal article (peer-reviewed)abstract
- Biofilm formation by Streptococcus pyogenes (GAS) in model systems mimicking the respiratory tract is poorly documented. Most studies have been conducted on abiotic surfaces, which poorly represent human tissues. We have previously shown that GAS forms mature and antibiotic-resistant biofilms on physiologically relevant epithelial cells. However, the role of the substratum, extracellular matrix (ECM) components, or GAS virulence factors for biofilm formation and structure is unclear. In this study, biofilm formation was measured on respiratory epithelial cells and keratinocytes by determining biomass and antibiotic resistance, and biofilm morphology was visualized using scanning electron microscopy. All GAS isolates tested formed biofilms that had similar, albeit not identical, biomass and antibiotic resistance for both cell types. Interestingly, functionally mature biofilms formed more rapidly on keratinocytes but were structurally denser and coated with more ECM on respiratory epithelial cells. The ECM was crucial for biofilm integrity, as protein- and DNA-degrading enzymes induced bacterial release from biofilms. Abiotic surfaces supported biofilm formation, but these biofilms were structurally less dense and organized. No major role of M protein, capsule, or Streptolysin O was observed in biofilm formation on epithelial cells, although some morphological differences were detected. NAD-glycohydrolase was required for optimal biofilm formation, whereas Streptolysin S or cysteine protease SpeB impaired this process. Finally, no correlation was found between cell adherence or auto-aggregation and GAS biofilm formation. Combined, these results provide a better understanding of the role of biofilm formation in GAS pathogenesis and can potentially provide novel targets for future treatments against GAS infections.
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| 5. |
- Alamiri, Feiruz, et al.
(author)
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HAMLET, a protein complex from human milk has bactericidal activity and enhances the activity of antibiotics against pathogenic Streptococci
- 2019
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In: Antimicrobial Agents and Chemotherapy. - 1098-6596. ; 63:12
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Journal article (peer-reviewed)abstract
- HAMLET is a protein-lipid complex derived from human milk that was first described for its tumoricidal activity. Later studies showed that HAMLET also has direct bactericidal activity against select species of bacteria, with highest activity against Streptococcus pneumoniae Additionally, HAMLET in combination with various antimicrobial agents can make a broader range of antibiotic-resistant bacterial species sensitive to antibiotics. Here, we show that HAMLET has direct antibacterial activity not only against pneumococci, but also against Streptococcus pyogenes (GAS) and Streptococcus agalactiae (GBS). Analogous to pneumococci, HAMLET-treatment of GAS and GBS resulted in depolarization of the bacterial membrane followed by membrane permeabilization and death that could be inhibited by calcium and sodium transport inhibitors. Treatment of clinical antibiotic-resistant isolates of S. pneumoniae, GAS, and GBS with sublethal concentrations of HAMLET in combination with antibiotics decreased the minimal inhibitory concentrations of the respective antibiotic into the sensitive range. This effect could also be blocked by ion transport inhibitors, suggesting that HAMLET's bactericidal and combination treatment effects used similar mechanisms. Finally, we show that HAMLET potentiated the effects of erythromycin against erythromycin-resistant bacteria more effectively than it potentiated killing by penicillin G of bacteria resistant to penicillin G. These results show for the first time that HAMLET effectively kills three different species of pathogenic Streptococci using similar mechanisms and also potentiate the activity of macrolides and lincosamides more effectively than combination treatment with beta-lactams. These findings suggest a potential therapeutic role for HAMLET in repurposing antibiotics currently causing treatment failures in patients.
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| 6. |
- Alamiri, Feiruz, et al.
(author)
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Role of serotype and virulence determinants of Streptococcus pyogenes biofilm bacteria in internalization and persistence in epithelial cells in vitro.
- 2023
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In: Frontiers in cellular and infection microbiology. - 2235-2988. ; 13
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Journal article (peer-reviewed)abstract
- Streptococcus pyogenes causes a multitude of local and systemic infections, the most common being pharyngitis in children. Recurrent pharyngeal infections are common and are thought to be due to the re-emergence of intracellular GAS upon completion of antibiotic treatment. The role of colonizing biofilm bacteria in this process is not fully clear. Here, live respiratory epithelial cells were inoculated with broth-grown or biofilm bacteria of different M-types, as well as with isogenic mutants lacking common virulence factors. All M-types tested adhered to and were internalized into epithelial cells. Interestingly, internalization and persistence of planktonic bacteria varied significantly between strains, whereas biofilm bacteria were internalized in similar and higher numbers, and all strains persisted beyond 44 hours, showing a more homogenous phenotype. The M3 protein, but not the M1 or M5 proteins, was required for optimal uptake and persistence of both planktonic and biofilm bacteria inside cells. Moreover, the high expression of capsule and SLO inhibited cellular uptake and capsule expression was required for intracellular survival. Streptolysin S was required for optimal uptake and persistence of M3 planktonic bacteria, whereas SpeB improved intracellular survival of biofilm bacteria. Microscopy of internalized bacteria showed that planktonic bacteria were internalized in lower numbers as individual or small clumps of bacteria in the cytoplasm, whereas GAS biofilm bacteria displayed a pattern of perinuclear localization of bacterial aggregates that affected actin structure. Using inhibitors targeting cellular uptake pathways, we confirmed that planktonic GAS mainly uses a clathrin-mediated uptake pathway that also required actin and dynamin. Clathrin was not involved in biofilm internalization, but internalization required actin rearrangement and PI3 kinase activity, possibly suggesting macropinocytosis. Together these results provide a better understanding of the potential mechanisms of uptake and survival of various phenotypes of GAS bacteria relevant for colonization and recurrent infection.
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| 7. |
- Barenkamp, Stephen J., et al.
(author)
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Panel 4 : Report of the Microbiology Panel
- 2017
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In: Otolaryngology - Head and Neck Surgery. - : Wiley. - 0194-5998 .- 1097-6817. ; 156:4_suppl, s. 51-62
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Journal article (peer-reviewed)abstract
- Objective: To perform a comprehensive review of the literature from July 2011 until June 2015 on the virology and bacteriology of otitis media in children. Data Sources: PubMed database of the National Library of Medicine. Review Methods: Two subpanels comprising experts in the virology and bacteriology of otitis media were created. Each panel reviewed the relevant literature in the fields of virology and bacteriology and generated draft reviews. These initial reviews were distributed to all panel members prior to meeting together at the Post-symposium Research Conference of the 18th International Symposium on Recent Advances in Otitis Media, National Harbor, Maryland, in June 2015. A final draft was created, circulated, and approved by all panel members. Conclusions: Excellent progress has been made in the past 4 years in advancing our understanding of the microbiology of otitis media. Numerous advances were made in basic laboratory studies, in animal models of otitis media, in better understanding the epidemiology of disease, and in clinical practice. Implications for Practice: (1) Many viruses cause acute otitis media without bacterial coinfection, and such cases do not require antibiotic treatment. (2) When respiratory syncytial virus, metapneumovirus, and influenza virus peak in the community, practitioners can expect to see an increase in clinical otitis media cases. (3) Biomarkers that predict which children with upper respiratory tract infections will develop otitis media may be available in the future. (4) Compounds that target newly identified bacterial virulence determinants may be available as future treatment options for children with otitis media.
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| 8. |
- Bergenfelz, Caroline, et al.
(author)
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Streptococcus pneumoniae Otitis Media Pathogenesis and How It Informs Our Understanding of Vaccine Strategies.
- 2017
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In: Current Otorhinolaryngology Report. - : Springer Science and Business Media LLC. - 2167-583X. ; 5:2, s. 115-124
-
Research review (peer-reviewed)abstract
- Purpose of Review This study aimed to review the literature regarding the mechanisms of transition from asymptomatic colonization to induction of otitis media and how the insight into the pathogenesis of otitis media has the potential to help design future otitis media-directed vaccines. Recent Findings Respiratory viruses have long been shown to predispose individuals to bacterial respiratory infections, such as otitis media. Recent information suggests that Streptococcus pneumoniae, which colonize the nasopharynx asymptomatical- ly, can sense potentially “threatening” changes in the nasopha- ryngeal environment caused by virus infection by upregulating specific sets of genes involved in biofilm release, dissemination from the nasopharynx to other sites, and protection against the host immune system. Furthermore, an understanding of the transcriptional and proteomic changes occurring in bacteria dur- ing transition to infection has led to identification of novel vaccine targets that are disease-specific and will not affect asymptomatic colonization. This approach will avoid major changes in the delicate balance of microorganisms in the respi- ratory tract microbiome due to elimination of S. pneumoniae. Summary Our recent findings are reviewed in the context of the current literature on the epidemiology and pathogenesis of otitis media. We also discuss how other otopathogens, such as Haemophilus influenzae and Moraxella catarrhalis, as well as the normal respiratory microbiome, can modulate the ability of pneumococci to cause infection. Furthermore, the unsatis- factory protection offered by the pneumococcal conjugate vaccines is highlighted and we review potential future strate- gies emerging to confer a more specific protection against otitis media.
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| 9. |
- Broman, Niroshani, et al.
(author)
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Problematic gaming and internet use but not gambling may be overrepresented in sexual minorities - A pilot population web survey study
- 2018
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In: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 9
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Journal article (peer-reviewed)abstract
- Background: Substance-related addictive disorders are known to be overrepresented in non-heterosexual individuals, but it is largely unknown whether this is also the case for behavioral addictions such as problem gaming and gambling. This study aimed, in a pilot web survey design, to assess whether problematic gambling, gaming and internet use may be more common in individuals with a non-heterosexual orientation. Methods: An online survey was distributed through media and social media, and answered by 605 individuals (51% women and 11% non-heterosexual). Problem gambling, problem gaming and problematic internet use were measured through structured screening instruments (the CLiP, the GAS and the PRIUSS, respectively). Results: Problem gaming and problematic internet use were significantly more prevalent in non-heterosexual subjects. Instead, problem gambling did not differ between heterosexual and non-heterosexual respondents. Psychological distress and social media use for more than 3 h daily were significantly more common in non-heterosexual respondents. In the overall sample, gaming and gambling were associated statistically. Conclusion: Based on the present pilot online survey, problematic gaming and internet use, but not problem gambling, may be more common in non-heterosexual populations. This area merits more and larger studies, and potentially preventive efforts aimed for non-heterosexual individuals in the population. Possible explanations and study limitations are discussed in the paper.
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| 10. |
- Chao, Yashuan, et al.
(author)
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Growing and Characterizing Biofilms Formed by Streptococcus pneumoniae
- 2019
-
In: Streptococcus pneumoniae : Methods and Protocols - Methods and Protocols. - New York, NY : Springer New York. - 1940-6029. - 9781493991990 - 9781493991983 ; 1968, s. 147-171
-
Book chapter (peer-reviewed)abstract
- It is estimated that over 80% of bacterial infections are associated with biofilm formation. Biofilms are organized bacterial communities formed on abiotic surfaces, such as implanted or inserted medical devices, or on biological surfaces, such as epithelial linings and mucosal surfaces. Biofilm growth is advantageous for the bacterial organism as it protects the bacteria from antimicrobial host factors and allows the bacteria to reside in the host without causing excessive inflammation. Like many other opportunistic pathogens of the respiratory tract, Streptococcus pneumoniae forms biofilms during asymptomatic carriage, which promotes, among other things, persistence in the niche, intraspecies and interspecies communication, and spread of bacterial DNA. Changes within the colonizing environment resulting from host assaults, such as virus infection, can induce biofilm dispersion where bacteria leave the biofilm and disseminate to other sites with ensuing infection. In this chapter, we present methodology to form complex biofilms in the nasopharynx of mice and to evaluate the biofilm structure and function in this environment. Furthermore, we present methods that recapitulate this biofilm phenotype in vitro by incorporating crucial factors associated with the host environment and describe how these models can be used to study biofilm function, transformation, and dispersion.
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