ORCID Profile
0000-0002-5073-2272
Current Organisations
Universidade Federal de São Carlos
,
SA Pathology
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Publisher: Springer Science and Business Media LLC
Date: 26-06-2015
DOI: 10.1007/S00248-015-0641-4
Abstract: Synergistetes strain MFA1 is an asaccharolytic ruminal bacterium isolated based on its ability to degrade fluoroacetate, a plant toxin. The amino acid and peptide requirements of the bacterium were investigated under different culturing conditions. The growth of strain MFA1 and its fluoroacetate degradation rate were enhanced by peptide-rich protein hydrolysates (tryptone and yeast extract) compared to casamino acid, an amino acid-rich protein hydrolysate. Complete utilization and preference for arginine, asparagine, glutamate, glycine, and histidine as free amino acids from yeast extract were observed, while the utilization of serine, threonine, and lysine in free form and peptide-bound glutamate was stimulated during growth on fluoroacetate. A predominant peptide in yeast extract preferentially utilized by strain MFA1 was partially characterized by high-liquid performance chromatography-mass spectrometry as a hepta-glutamate oligopeptide. Similar utilization profiles of amino acids were observed between the co-culture of strain MFA1 with Methanobrevibacter smithii without fluoroacetate and pure strain MFA1 culture with fluoroacetate. This suggests that growth of strain MFA1 could be enhanced by a reduction of hydrogen partial pressure as a result of hydrogen removal by a methanogen or reduction of fluoroacetate.
Publisher: Springer Science and Business Media LLC
Date: 17-11-2015
DOI: 10.1038/SREP16350
Abstract: Sequencing-based studies of the human faecal microbiota are increasingly common. Appropriate storage of s le material is essential to avoid the introduction of post-collection bias in microbial community composition. Rapid freezing to −80 °C is commonly considered to be best-practice. However, this is not feasible in many studies, particularly those involving s le collection in participants’ homes. We determined the extent to which a range of stabilisation and storage strategies maintained the composition of faecal microbial community structure relative to freezing to −80 °C. Refrigeration at 4 °C, storage at ambient temperature and the use of several common preservative buffers (RNAlater, OMNIgene.GUT, Tris-EDTA) were assessed relative to freezing. Following 72 hours of storage, faecal microbial composition was assessed by 16 S rRNA licon sequencing. Refrigeration was associated with no significant alteration in faecal microbiota ersity or composition. However, s les stored using other conditions showed substantial ergence compared to −80 °C control s les. Aside from refrigeration, the use of OMNIgene.GUT resulted in the least alteration, while the greatest change was seen in s les stored in Tris-EDTA buffer. The commercially available OMNIgene.GUT kit may provide an important alternative where refrigeration and cold chain transportation is not available.
Publisher: Springer Science and Business Media LLC
Date: 19-04-2016
DOI: 10.1038/MP.2016.46
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.IJPORL.2015.07.013
Abstract: Indigenous Australian children have a high prevalence of otitis media with effusion (OME) and associated conductive hearing loss. Only three microbiological studies of middle ear fluid (MEF) from Indigenous Australian children with OME have been reported. All of these were reliant on culture or species-specific PCR assays. The aim of this study was to characterise the middle ear fluid (MEF), adenoid and nasopharyngeal (NP) microbiomes of Indigenous Australian children, using culture-independent 16S rRNA gene sequencing. MEF, NP swabs and adenoid specimens were collected from 11 children in the Alice Springs region of Central Australia. Bacterial communities in these specimens were characterised using 16S rRNA gene sequencing. The microbiota in MEF s les were dominated (>50% relative abundance) by operational taxonomic units (OTUs) consistent with Alloiococcus otitidis (6/11), Haemophilus influenzae (3/11) or Streptococcus sp. (specifically, Mitis group streptococci which includes Streptococcus pneumoniae) (1/11). Anatomical site selectivity was indicated by the presence of a single conserved Haemophilus OTU in 7/11 MEF s les. In comparison, there were ten distinct Haemophilus OTUs observed across the NP and adenoid s les. Despite significant differences between the MEF and NP/adenoid microbiomes, Streptococcus sp., H. influenzae and Moraxella catarrhalis OTUs were common to all s le types. Co-occurrence of classical otopathogens in paired MEF and NP/Adenoid s les is consistent with earlier culture-based studies. These data highlight the need to further assess H. influenzae traits important in otitis media and to understand the role of canal flora, especially A. otitidis, in populations with a high prevalence of tympanic membrane perforation.
Publisher: Informa UK Limited
Date: 25-10-2019
Publisher: Springer Science and Business Media LLC
Date: 05-05-2015
Publisher: American Society for Microbiology
Date: 25-04-2018
Abstract: Recent demonstrations that long-term macrolide therapy can prevent exacerbations in chronic airways diseases have led to a dramatic increase in their use. However, little is known about the wider, potentially adverse impacts of these treatments. Substantial disruption of the upper airway commensal microbiota might reduce its contribution to host defense and local immune regulation, while increases in macrolide resistance carriage would represent a serious public health concern. Using s les from a randomized controlled trial, we show that low-dose erythromycin given over 48 weeks influences the composition of the oropharyngeal commensal microbiota. We report that macrolide therapy is associated with significant changes in the relative abundances of members of the Actinomyces genus and with significant increases in the carriage of transmissible macrolide resistance. Determining the clinical significance of these changes, relative to treatment benefit, now represents a research priority.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Frontiers Media SA
Date: 11-04-2017
Publisher: American Society for Microbiology
Date: 09-2016
DOI: 10.1128/JCM.01410-16
Abstract: Culture-based detection of nontuberculous Mycobacteria (NTM) in respiratory s les is time consuming and can be subject to overgrowth by nonmycobacterial bacteria. We describe a single-reaction TaqMan quantitative PCR assay for the direct detection of NTM species in clinical s les that is specific, sensitive, and robust.
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.JACI.2017.03.044
Abstract: Asthma pathophysiology and treatment responsiveness are predicted by inflammatory phenotype. However, the relationship between airway microbiology and asthma phenotype is poorly understood. We aimed to characterize the airway microbiota in patients with symptomatic stable asthma and relate composition to airway inflammatory phenotype and other phenotypic characteristics. The microbial composition of induced sputum specimens collected from adult patients screened for a multicenter randomized controlled trial was determined by using 16S rRNA gene sequencing. Inflammatory phenotypes were defined by sputum neutrophil and eosinophil cell proportions. Microbiota were defined by using α- and β- ersity measures, and interphenotype differences were identified by using similarity of percentages, network analysis, and taxon fold change. Phenotypic predictors of airway microbiology were identified by using multivariate linear regression. Microbiota composition was determined in 167 participants and classified as eosinophilic (n = 84), neutrophilic (n = 14), paucigranulocytic (n = 60), or mixed neutrophilic-eosinophilic (n = 9) asthma phenotypes. Airway microbiology was significantly less erse (P = .022) and more dissimilar (P = .005) in neutrophilic compared with eosinophilic participants. Sputum neutrophil proportions, but not eosinophil proportions, correlated significantly with these ersity measures (α- ersity: Spearman r = -0.374, P < .001 β- ersity: r = 0.238, P = .002). Interphenotype differences were characterized by a greater frequency of pathogenic taxa at high relative abundance and reduced Streptococcus, Gemella, and Porphyromonas taxa relative abundance in patients with neutrophilic asthma. Multivariate regression confirmed that sputum neutrophil proportion was the strongest predictor of microbiota composition. Neutrophilic asthma is associated with airway microbiology that is significantly different from that seen in patients with other inflammatory phenotypes, particularly eosinophilic asthma. Differences in microbiota composition might influence the response to antimicrobial and steroid therapies and the risk of lung infection.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2018
Publisher: The Endocrine Society
Date: 03-2017
DOI: 10.1210/EN.2016-1839
Abstract: Serotonin (5-hydroxytryptamine or 5-HT) is a multifunctional bioamine with important signaling roles in a range of physiological pathways. Almost all of the 5-HT in our bodies is synthesized in specialized enteroendocrine cells within the gastrointestinal (GI) mucosa called enterochromaffin (EC) cells. These cells provide all of our circulating 5-HT. We have long appreciated the important contributions of 5-HT within the gut, including its role in modulating GI motility. However, evidence of the physiological and clinical significance of gut-derived 5-HT outside of the gut has recently emerged, implicating 5-HT in regulation of glucose homeostasis, lipid metabolism, bone density, and diseases associated with metabolic syndrome, such as obesity and type 2 diabetes. Although a new picture has developed in the last decade regarding the various metabolic roles of peripheral serotonin, so too has our understanding of the physiology of EC cells. Given that they are scattered throughout the lining of the GI tract within the epithelial cell layer, these cells are typically difficult to study. Advances in isolation procedures now allow the study of pure EC-cell cultures and single cells, enabling studies of EC-cell physiology to occur. EC cells are sensory cells that are capable of integrating cues from ingested nutrients, the enteric nervous system, and the gut microbiome. Thus, levels of peripheral 5-HT can be modulated by a multitude of factors, resulting in both local and systemic effects for the regulation of a raft of physiological pathways related to metabolism and obesity.
Publisher: Informa UK Limited
Date: 04-01-2019
Publisher: PAGEPress Publications
Date: 08-2018
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.JPEDS.2017.08.070
Abstract: To assess whether features of the infant intestinal microbiome, including the carriage of toxigenic bacteria, are associated with sudden infant death syndrome (SIDS). We undertook a case-controlled analysis of fecal microbiology in SIDS. Fecal material was obtained from 44 cases and 44 aged-matched controls. Microbiota composition was determined by 16S ribosomal RNA gene licon sequencing and comparisons between cases and controls made based on both bacterial alpha ersity measures and unconstrained ordination. Specific quantitative polymerase chain reaction assays were used to determine intestinal carriage of Staphylococcus aureus, toxigenic Clostridium difficile, and pathogenic and nonpathogenic Escherichia coli. The microbial composition for the study population as a whole was consistent with previous studies of infants <12 months of age, with a correlation between alpha ersity and age (r We found no evidence of an association between altered intestinal microbiology and SIDS, or to support the development of strategies to reduce the incidence of SIDS that target intestinal microbiology.
Publisher: American Society for Microbiology
Date: 17-08-2017
Abstract: Enterobacter cloacae is a common member of the gut microbiota in healthy in iduals. However, it is also an opportunistic pathogen, capable of causing bacteremia. We report the draft genomes of two Enterobacter cloacae subspecies cloacae strains isolated from hematology patients with bacteremia. Both isolates carry genes encoding extended-spectrum β-lactamases.
Publisher: Springer Science and Business Media LLC
Date: 06-2017
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.CLINBIOMECH.2017.02.009
Abstract: Gait adaptations, including toe out gait, have been proposed as treatments for knee osteoarthritis. The clinical application of toe out gait, however, is unclear. This study aims to identify the changes in Knee adduction moment in varus knee deformity assessing toe out gait as an alternative to high tibial osteotomy, and if any change in dynamic loading persists post operatively, when anatomical alignment is restored. Three-dimensional motion analysis was performed on 17 patients with medial compartment knee osteoarthritis and varus deformity prior to undergoing high tibial osteotomy, 13 patients were assessed post-operatively, and results compared to 13 healthy controls. Pre-operatively, there was no significant difference between natural and toe out gait for measures of knee adduction moment. Post high tibial osteotomy, first (2.70 to 1.51% BW·h) and second peak (2.28 to 1.21% BW·h) knee adduction moment were significantly reduced, as was knee adduction angular impulse (1.00 to 0.52% BW·h·s), to a healthy level. Adopting toe out gait post-operatively reduced the second peak further to a level below that of healthy controls. Increasing the foot progression angle from 20° (natural) to 30° in isolation did not significantly alter the knee adduction moment or angular impulse. This suggests that adopting a toe out gait, in isolation, in an already high natural foot progression angle, is not of benefit. Adopting toe out gait post-operatively, however, resulted in a further reduction in the second peak to below that of the healthy control cohort, however, this may increase lateral compartment load.
Publisher: American Society for Microbiology
Date: 22-02-2017
Abstract: Despite the fundamental importance of antibiotic therapies to human health, their functional impact on the intestinal microbiome and its subsequent ability to recover are poorly understood. Much research in this area has focused on changes in microbiota composition, despite the interdependency and overlapping functions of many members of the microbial community. These relationships make prediction of the functional impact of microbiota-level changes difficult, while analyses based on the metabolome alone provide relatively little insight into the taxon-level changes that underpin changes in metabolite levels. Here, we used combined microbiota and metabolome profiling to characterize changes associated with clinically important antibiotic combinations with distinct effects on the gut. Correlation analysis of changes in the metabolome and microbiota indicate that a combined approach will be essential for a mechanistic understanding of the functional impact of distinct antibiotic classes.
Publisher: American Thoracic Society
Date: 08-2019
Location: Brazil
Location: Australia
No related grants have been discovered for Lex Ee Xiang Leong.