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Profile Details
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★★★★★
☆☆☆☆☆
USD 50 /hr
Hire Dr. Helina M.
United Kingdom
USD 50 /hr

Freelance Editor, Medical Writer and Microbiology Consultant with 13+ years of experience

Profile Summary
Subject Matter Expertise
Services
Writing Technical Writing, Newswriting
Research Market Research, User Research, Fact Checking, Gap Analysis, Gray Literature Search, Systematic Literature Review, Secondary Data Collection
Consulting Scientific and Technical Consulting
Data & AI Statistical Analysis, Data Visualization, Data Processing
Product Development Product Evaluation
Work Experience

Queen's University Belfast

- Present

Research scientist / Research fellow

University College Dublin

March 2019 - Present

Postdoctoral Research Fellow

Queen's University Belfast

July 2016 - Present

Research assistant

Baylor College of Medicine

May 2011 - September 2011

Intern

Baylor College of Medicine

June 2010 - September 2010

Education

Clinical Microbiology

University College London, University of London

September 2012 - June 2016

BSc (Hons) Biological Sciences

Edinburgh Napier University

October 2008 - June 2012

Certifications
  • Certification details not provided.
Publications
JOURNAL ARTICLE
Helina Marshall, Maria Fernandes(2021). Early‐career researchers shaping publishing strategy . Learned Publishing. 34. (4). p. 675--678. Wiley
Helina Marshall, Julie P. Meneely, Brian Quinn, Yueju Zhao, Paula Bourke, Brendan F. Gilmore, Guangtao Zhang, Christopher T. Elliott(2020). Novel decontamination approaches and their potential application for post-harvest aflatoxin control . Trends in Food Science & Technology. 106. p. 489--496. Elsevier {BV}
Helina Marshall, Daniel Storey, Matthew R. Parsek, Alan McNally, Mia Åstrand, Joana sa-Pessoa Graca Santos, Isabel Rodriguez-Escudero, Bronagh Elmore, Leyre Palacios, Laura Hobley, et al.(2020). Klebsiella pneumoniae type VI secretion system-mediated microbial competition is PhoPQ controlled and reactive oxygen species dependent . PLOS Pathogens. 16. (3). p. e1007969. Public Library of Science ({PLoS})
Klebsiella pneumoniae type VI secretion system-mediated microbial competition is PhoPQ controlled and reactive oxygen species dependent @article{0d9ea03131ff411fa971cf0c901d98a9, title = "Klebsiella pneumoniae type VI secretion system-mediated microbial competition is PhoPQ controlled and reactive oxygen species dependent", abstract = "Klebsiella pneumoniae is recognized as an urgent threat to human health due to the increasing isolation of multidrug resistant strains. Hypervirulent strains are a major concern due to their ability to cause life-threating infections in healthy hosts. The type VI secretion system (T6SS) is widely implicated in microbial antagonism, and it mediates interactions with host eukaryotic cells in some cases. In silico search for genes orthologous to T6SS component genes and T6SS effector genes across 700 K. pneumoniae genomes shows extensive diversity in T6SS genes across the K. pneumoniae species. Temperature, oxygen tension, pH, osmolarity, iron levels, and NaCl regulate the expression of the T6SS encoded by a hypervirulent K. pneumoniae strain. Polymyxins and human defensin 3 also increase the activity of the T6SS. A screen for regulators governing T6SS uncover the correlation between the transcription of the T6SS and the ability to kill E. coli prey. Whereas H-NS represses the T6SS, PhoPQ, PmrAB, Hfq, Fur, RpoS and RpoN positively regulate the T6SS. K. pneumoniae T6SS mediates intra and inter species bacterial competition. This antagonism is only evident when the prey possesses an active T6SS. The PhoPQ two component system governs the activation of K. pneumoniae T6SS in bacterial competitions. Mechanistically, PhoQ periplasmic domain, and the acid patch within, is essential to activate K. pneumoniae T6SS. Klebsiella T6SS also mediates anti-fungal competition. We have delineated the contribution of each of the individual VgrGs in microbial competition and identified VgrG4 as a T6SS effector. The DUF2345 domain of VgrG4 is sufficient to intoxicate bacteria and yeast. ROS generation mediates the antibacterial effects of VgrG4, and the antitoxin Sel1E protects against the toxic activity of VgrG4. Our findings provide a better understanding of the regulation of the T6SS in bacterial competitions, and place ROS as an early event in microbial competition.", author = "Daniel Storey and Alan McNally and Mia {\AA}strand and {Sa-Pessoa Graca Santos}, Joana and Isabel Rodriguez-Escudero and Bronagh Elmore and Leyre Palacios and Helina Marshall and Laura Hobley and Maria Molina and Cid, {Victor J} and Salminen, {Tiina A} and Bengoechea, {Jose A}", year = "2020", month = mar, day = "19", doi = "10.1371/journal.ppat.1007969", language = "English", volume = "16", journal = "PLoS Pathogens", issn = "1553-7366", publisher = "Public Library of Science", number = "3", } . PLoS Pathogens.
In Vivo Relationship between the Nano Biomechanical Properties of Streptococcal Polysaccharide Capsules and Virulence Phenotype @article{b84da1c4cbec4896bd3f954ddb8cedc1, title = "In Vivo Relationship between the Nano Biomechanical Properties of Streptococcal Polysaccharide Capsules and Virulence Phenotype", abstract = "In common with many bacterial pathogens, Streptococcus pneumoniae has a polysaccharide capsule which facilitates immune evasion and determines virulence. Recent data have shown that the closely related Streptococcus mitis also expresses polysaccharide capsules including those with an identical chemical structure to S. pneumoniae capsular serotypes. We utilized atomic force microscopy (AFM) techniques to investigate the biophysical properties of S. mitis and S. pneumoniae strains expressing the same capsular serotypes that might relate to differences in virulence potential. When comparing S. mitis and S. pneumoniae strains with identical capsule serotypes, S. mitis strains were susceptible to neutrophil killing, and electron microscopy and AFM demonstrated significant morphological differences. Force–volume mapping using AFM showed distinct force–curve profiles for the center and edge areas of encapsulated streptococcal strains. This “edge effect” was not observed in unencapsulated bacteria and therefore was a direct representation of the mechanical properties of the bacterial capsule. When two strains of S. mitis and S. pneumoniae expressed an identical capsular serotype, they presented similar biomechanical characteristics. This infers a potential relationship between capsule biochemistry and nanomechanics, independent of bacterial strain. Overall, this study demonstrates that it is possible to investigate reproducibly the mechanistic, structural, and mechanical properties of both the capsule and the body of individual living bacterial cells and relate the data to virulence phenotypes. We have demonstrated that using nanomechanics to investigate individual bacterial cells we can now begin to identify the surface properties bacterial pathogens require to avoid host-mediated immunity.", author = "Helina Marshall and Sebastian Aguayo and Mogens Kilian and Fernanda Petersen and Laurent Bozec and Jeremy Brown", year = "2019", month = dec, day = "19", doi = "10.1021/acsnano.9b08631", language = "English", journal = "ACS Nano", issn = "1936-0851", publisher = "American Chemical Society", } . ACS Nano.
Helina Marshall, Norman K. Fry, Tasha Mellins-Cohen(2019). In praise of preprints . Journal of Medical Microbiology. 68. (4). p. 503--505. Microbiology Society
Helina Marshall, Norman K. Fry, Tasha Mellins-Cohen(2019). In praise of preprints . Access Microbiology. 1. (2). Microbiology Society
Fry NK, Marshall H, Mellins-Cohen T(2019). In praise of preprints . Microbial genomics.
Fry NK, Marshall H, Mellins-Cohen T(2019). In praise of preprints . Microbiology (Reading, England).
Fry NK, Marshall H, Mellins-Cohen T(2019). In praise of preprints . The Journal of general virology.
Fry NK, Marshall H, Mellins-Cohen T(2019). In praise of preprints . Journal of medical microbiology.
Fry NK, Marshall H, Mellins-Cohen T(2019). In praise of preprints . International journal of systematic and evolutionary microbiology.
Fry, N.K., Marshall, H., Tasha Mellins-Cohen(2019). In praise of preprints . Microbiology (United Kingdom). 165. (5). p. 489-491.
Fry, N.K., Marshall, H., Mellins-Cohen, T.(2019). In praise of preprints . International Journal of Systematic and Evolutionary Microbiology. 69. (7). p. 1841-1843.
Fry, N.K., Marshall, H., Mellins-Cohen, T.(2019). In praise of preprints . Journal of General Virology. 100. (5). p. 733-735.
Fry, N.K., Marshall, H., Mellins-Cohen, T.(2019). In praise of preprints . Journal of Medical Microbiology. 68. (4). p. 503-505.
Early Adhesion of Candida albicans onto Dental Acrylic Surfaces @article{d5251d6a802343f792b1cb4beab306f1, title = "Early Adhesion of Candida albicans onto Dental Acrylic Surfaces", abstract = "Denture-associated stomatitis is a common candidal infection that may give rise to painful oral symptoms, as well as be a reservoir for infection at other sites of the body. As poly (methyl methacrylate) (PMMA) remains the main material employed in the fabrication of dentures, the aim of this research was to evaluate the adhesion of Candida albicans cells onto PMMA surfaces by employing an atomic force microscopy (AFM) single-cell force spectroscopy (SCFS) technique. For experiments, tipless AFM cantilevers were functionalized with PMMA microspheres and probed against C. albicans cells immobilized onto biopolymer-coated substrates. Both a laboratory strain and a clinical isolate of C. albicans were used for SCFS experiments. Scanning electron microscopy (SEM) and AFM imaging of C. albicans confirmed the polymorphic behavior of both strains, which was dependent on growth culture conditions. AFM force-spectroscopy results showed that the adhesion of C. albicans to PMMA is morphology dependent, as hyphal tubes had increased adhesion compared with yeast cells ( P < 0.05). C. albicans budding mother cells were found to be nonadherent, which contrasts with the increased adhesion observed in the tube region. Comparison between strains demonstrated increased adhesion forces for a clinical isolate compared with the lab strain. The clinical isolate also had increased survival in blood and reduced sensitivity to complement opsonization, providing additional evidence of strain-dependent differences in Candida-host interactions that may affect virulence. In conclusion, PMMA-modified AFM probes have shown to be a reliable technique to characterize the adhesion of C. albicans to acrylic surfaces.", keywords = "Acrylic Resins, Biofilms, Candida albicans, Cell Adhesion, Dental Materials, Microscopy, Atomic Force, Microscopy, Electron, Scanning, Polymethyl Methacrylate, Spectrum Analysis, Surface Properties, Journal Article", author = "S Aguayo and H Marshall and J Pratten and D Bradshaw and Brown, {J S} and Porter, {S R} and D Spratt and L Bozec", year = "2017", month = jul, day = "1", doi = "10.1177/0022034517706354", language = "English", volume = "96", pages = "917--923", journal = "Journal of Dental Research", issn = "0022-0345", publisher = "AMER ASSOC DENTAL RESEARCH", number = "8", } . Journal of Dental Research.
Wilson, R., Cohen, J.M., Reglinski, M., Jose, R.J., Chan, W.Y., Marshall, H., de Vogel, C., Gordon, S., Goldblatt, D., Petersen, F.C., et al.(2017). Erratum: Correction: Naturally Acquired Human Immunity to Pneumococcus Is Dependent on Antibody to Protein Antigens (PLoS pathogens (2017) 13 1 (e1006137)) . PLoS pathogens. 13. (3). p. e1006259.
Aguayo, S., Marshall, H., Pratten, J., Bradshaw, D., Brown, J.S., Porter, S.R., Spratt, D., Bozec, L.(2017). Early Adhesion of Candida albicans onto Dental Acrylic Surfaces . Journal of Dental Research. 96. (8). p. 917-923.
Wilson, R., Cohen, J.M., Reglinski, M., Jose, R.J., Chan, W.Y., Marshall, H., de Vogel, C., Gordon, S., Goldblatt, D., Petersen, F.C., et al.(2017). Naturally Acquired Human Immunity to Pneumococcus Is Dependent on Antibody to Protein Antigens . PLoS Pathogens. 13. (1).
Importance of bacterial replication and alveolar macrophage-independent clearance mechanisms during early lung infection with Streptococcus pneumoniae @article{932499c57f924cd985929610305b66ef, title = "Importance of bacterial replication and alveolar macrophage-independent clearance mechanisms during early lung infection with Streptococcus pneumoniae", abstract = "Although the importance of alveolar macrophages for host immunity during early Streptococcus pneumoniae lung infection is well established, the contribution and relative importance of other innate immunity mechanisms and of bacterial factors are less clear. We have used a murine model of S. pneumoniae early lung infection with wild-type, unencapsulated, and para-amino benzoic acid auxotroph mutant TIGR4 strains to assess the effects of inoculum size, bacterial replication, capsule, and alveolar macrophage-dependent and -independent clearance mechanisms on bacterial persistence within the lungs. Alveolar macrophage-dependent and -independent (calculated indirectly) clearance half-lives and bacterial replication doubling times were estimated using a mathematical model. In this model, after infection with a high-dose inoculum of encapsulated S. pneumoniae, alveolar macrophage-independent clearance mechanisms were dominant, with a clearance half-life of 24 min compared to 135 min for alveolar macrophage-dependent clearance. In addition, after a high-dose inoculum, successful lung infection required rapid bacterial replication, with an estimated S. pneumoniae doubling time of 16 min. The capsule had wide effects on early lung clearance mechanisms, with reduced half-lives of 14 min for alveolar macrophage-independent and 31 min for alveolar macrophage-dependent clearance of unencapsulated bacteria. In contrast, with a lower-dose inoculum, the bacterial doubling time increased to 56 min and the S. pneumoniae alveolar macrophage-dependent clearance half-life improved to 42 min and was largely unaffected by the capsule. These data demonstrate the large effects of bacterial factors (inoculum size, the capsule, and rapid replication) and alveolar macrophage-independent clearance mechanisms during early lung infection with S. pneumoniae.", keywords = "4-Aminobenzoic Acid, Animals, Bacterial Capsules, Bacterial Load, Female, Half-Life, Immunity, Innate, Lung, Macrophages, Alveolar, Male, Mice, Mice, Inbred Strains, Models, Statistical, Mutation, Phagocytosis, Pneumonia, Pneumococcal, Severity of Illness Index, Streptococcus pneumoniae, Time Factors, Journal Article, Research Support, Non-U.S. Gov't", author = "Emilie Camberlein and Cohen, {Jonathan M} and Ricardo Jos{\'e} and Hyams, {Catherine J} and Robin Callard and Suneeta Chimalapati and Jose Yuste and Edwards, {Lindsey A} and Helina Marshall and {van Rooijen}, Nico and Mahdad Noursadeghi and Brown, {Jeremy S}", note = "Copyright {\textcopyright} 2015, American Society for Microbiology. All Rights Reserved.", year = "2015", month = mar, doi = "10.1128/IAI.02788-14", language = "English", volume = "83", pages = "1181--1189", journal = "Infection and Immunity", issn = "0019-9567", publisher = "American Society for Microbiology", number = "3", } . Infection and Immunity.
Camberlein, E., Cohen, J.M., Jos&#233;, R., Hyams, C.J., Callard, R., Chimalapati, S., Yuste, J., Edwards, L.A., Marshall, H., van Rooijen, N., et al.(2015). Importance of bacterial replication and alveolar macrophage-independent clearance mechanisms during early lung infection with Streptococcus pneumoniae . Infection and Immunity. 83. (3). p. 1181-1189.
Protective role of the capsule and impact of serotype 4 switching on Streptococcus mitis @article{07ca5f3bd254417a963d852f25ccf7f0, title = "Protective role of the capsule and impact of serotype 4 switching on Streptococcus mitis", abstract = "The polysaccharide capsule surrounding Streptococcus pneumoniae is essential for virulence. Recently, Streptococcus mitis, a human commensal and a close relative of S. pneumoniae, was also shown to have a capsule. In this study, the S. mitis type strain switched capsule by acquisition of the serotype 4 capsule locus of S. pneumoniae TIGR4, following induction of competence for natural transformation. Comparison of the wild type with the capsule-switching mutant and with a capsule deletion mutant showed that the capsule protected S. mitis against phagocytosis by RAW 264.7 macrophages. This effect was enhanced in the S. mitis strain expressing the S. pneumoniae capsule, which showed, in addition, increased resistance against early clearance in a mouse model of lung infection. Expression of both capsules also favored survival in human blood, and the effect was again more pronounced for the capsule-switching mutant. S. mitis survival in horse blood or in a mouse model of bacteremia was not significantly different between the wild type and the mutant strains. In all models, S. pneumoniae TIGR4 showed higher rates of survival than the S. mitis type strain or the capsule-switching mutant, except in the lung model, in which significant differences between S. pneumoniae TIGR4 and the capsule-switching mutant were not observed. Thus, we identified conditions that showed a protective function for the capsule in S. mitis. Under such conditions, S. mitis resistance to clearance could be enhanced by capsule switching to serotype 4, but it was enhanced to levels lower than those for the virulent strain S. pneumoniae TIGR4.", keywords = "Animals, Bacteremia, Bacterial Capsules, Cell Line, Disease Models, Animal, Female, Horses, Humans, Lung, Macrophages, Mice, Mice, Inbred BALB C, Phagocytosis, Respiratory Tract Infections, Serotyping, Streptococcal Infections, Streptococcus mitis, Streptococcus pneumoniae, Virulence, Journal Article, Research Support, Non-U.S. Gov't", author = "Rukke, {H{\aa}kon V} and Kalluru, {Raja Sab} and Urska Repnik and Alice Gerlini and Jos{\'e}, {Ricardo J} and Jimstan Periselneris and Helina Marshall and Gareth Griffiths and Oggioni, {Marco Rinaldo} and Brown, {Jeremy S} and Petersen, {Fernanda C}", note = "Copyright {\textcopyright} 2014, American Society for Microbiology. All Rights Reserved.", year = "2014", month = sep, doi = "10.1128/IAI.01840-14", language = "English", volume = "82", pages = "3790--3801", journal = "Infection and Immunity", issn = "0019-9567", publisher = "American Society for Microbiology", number = "9", } . Infection and Immunity.
Rukke, H.V., Kalluru, R.S., Repnik, U., Gerlini, A., Jos&#233;, R.J., Periselneris, J., Marshall, H., Griffiths, G., Oggioni, M.R., Brown, J.S., et al.(2014). Protective role of the capsule and impact of serotype 4 switching on Streptococcus mitis . Infection and Immunity. 82. (9). p. 3790-3801.
OTHER
Klebsiella pneumoniae type VI secretion system-mediated microbial competition is PhoPQ controlled and reactive oxygen species dependent @misc{1585322001254ef099df2fb415b6df94, title = "Klebsiella pneumoniae type VI secretion system-mediated microbial competition is PhoPQ controlled and reactive oxygen species dependent", abstract = "Klebsiella pneumoniae is recognized as an urgent threat to human health due to the increasing isolation of multidrug resistant strains. Hypervirulent strains are a major concern due to their ability to cause life-threating infections in healthy hosts. The type VI secretion system (T6SS) is widely implicated in microbial antagonism, and it mediates interactions with host eukaryotic cells in some cases. In silico search for genes orthologous to T6SS component genes and T6SS effector genes across 700 K. pneumoniae genomes shows extensive diversity in T6SS genes across the K. pneumoniae species. Temperature, oxygen tension, pH, osmolarity, iron levels, and NaCl regulate the expression of the T6SS encoded by a hypervirulent K. pneumoniae strain. Polymyxins and human defensin 3 also increase the activity of the T6SS. A screen for regulators governing T6SS uncover the correlation between the transcription of the T6SS and the ability to kill E. coli prey. Whereas H-NS represses the T6SS, PhoPQ, PmrAB, Hfq, Fur, RpoS and RpoN positively regulate the T6SS. K. pneumoniae T6SS mediates intra and inter species bacterial competition. This antagonism is only evident when the prey possess an active T6SS. The PhoPQ two component system governs the activation of K. pneumoniae T6SS in bacterial competitions. Mechanistically, PhoQ periplasmic domain, and the acid patch within, is essential to activate K. pneumoniae T6SS. Klebsiella T6SS also mediates anti-fungal competition. We have delineated the contribution of each of the individual VgrGs in microbial competition, and identified VgrG4 as a T6SS effector. Structurally, domain DUF2345 of VgrG4 is sufficient to intoxicate bacteria and yeast. ROS generation mediates the antibacterial effects of VgrG4, and the antitoxin Sel1E protects against the toxic activity of VgrG4. Our findings provide a better understanding of the regulation of the T6SS in bacterial competitions, and place ROS as an early event in microbial competition.", author = "Helina Marshall", year = "2019", month = jul, day = "10", language = "English", type = "Other", } .
Helina Marshall, Daniel Storey, Alan McNally, Mia &#197;strand, Joana S&#225;-Pessoa Graca Santos, Isabel Rodriguez-Escudero, Bronagh Elmore, Leyre Palacios, Laura Hobley, Maria Molina Martin, et al.(2019). Klebsiella pneumoniaetype VI secretion system-mediated microbial competition is PhoPQ controlled and reactive oxygen species dependent . Cold Spring Harbor Laboratory
Helina Marshall, Norman K. Fry, Tasha Mellins-Cohen(2019). In Praise of Pre-Prints . Microbial Genomics. 5. (4). Microbiology Society