ORCID Profile
0000-0001-7844-323X
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Publisher: American Society for Microbiology
Date: 11-2004
DOI: 10.1128/JCM.42.11.5357-5361.2004
Abstract: We report evidence of interspecies gene transfer between the important virulence factor genes sfbI and gfbA . Because the identified group G streptococcus gfbA types possess DNA cassettes that can be identified in a number of group A streptococcus strains, it appears that homologous recombination is occurring between these species.
Publisher: Springer Science and Business Media LLC
Date: 08-1991
DOI: 10.1007/BF01025251
Publisher: Springer Science and Business Media LLC
Date: 26-03-2013
DOI: 10.1007/S10096-013-1854-4
Abstract: Peripheral venous catheters (PVCs) are some of the most widely used medical devices in hospitals worldwide. PVC-related infections increase morbidity and treatment costs. The inner surfaces of PVCs are rarely examined for the population structure of bacteria, as it is generally believed that bacteria at this niche are similar to those on the external surface of PVCs. We primarily test this hypothesis and also study the effect of antibiotic treatment on bacterial communities from PVC surfaces. The inner and outer surfaces of PVCs from 15 patients were examined by 454 GS FLX Titanium 16S rRNA sequencing and the culture method. None of the PVCs were colonised according to the culture method and none of the patients had a bacteraemia. From a total of 127,536 high-quality sequence reads, 14 bacterial phyla and 268 erse bacterial genera were detected. The number of operational taxonomic units for each s le was in the range of 86-157, even though 60 % of patients had received antibiotic treatment. Stenotrophomonas maltophilia was the predominant bacterial species in all the examined PVC s les. There were noticeable but not statistically significant differences between the inner and outer surfaces of PVCs in terms of the distribution of the taxonomic groups. In addition, the bacterial communities on PVCs from antibiotic-treated patients were significantly different from untreated patients. In conclusion, the surfaces of PVCs display complex bacterial communities. Although their significance has yet to be determined, these findings alter our perception of PVC-related infections.
Publisher: Cambridge University Press (CUP)
Date: 06-2002
DOI: 10.1017/S0950268802006787
Abstract: Streptococcus pyogenes (group A streptococcus) strains may express several distinct fibronectin-binding proteins (FBPs) which are considered as major streptococcal adhesins. Of the FBPs, SfbI was shown in vitro to promote internalization of the bacterium into host cells and has been implicated in persistence. In the tropical Northern Territory, where group A streptococcal infection is common, multiple genotypes of the organism were found among isolates from invasive disease cases and no dominant strains were observed. To determine whether any FBPs is associated with invasive disease propensity of S. pyogenes , we have screened streptococcal isolates from bacteraemic and necrotizing fasciitis patients and isolates from uncomplicated infections for genetic endowment of 4 FBPs. No difference was observed in the distribution of sfbII , fbp54 and sfbI between the blood isolates and isolates from uncomplicated infection. We conclude that the presence of sfbI does not appear to promote invasive diseases, despite its association with persistence. We also show a higher proportion of group A streptococcus strains isolated from invasive disease cases possess prtFII when compared to strains isolated from non-invasive disease cases. We suggest that S. pyogenes may recruit different FBPs for different purposes.
Publisher: Springer Science and Business Media LLC
Date: 13-08-2019
DOI: 10.1038/S41598-019-47892-0
Abstract: Multiple parasitic arthropods of medical importance depend on symbiotic bacteria. While the link between scabies and secondary bacterial infections causing post infective complications of Group A streptococcal and staphylococcal pyoderma is increasingly recognized, very little is known about the microbiota of Sarcoptes scabiei . Here we analyze adult female mite and egg metagenome datasets. The majority of adult mite bacterial reads matched with Enterobacteriaceae (phylum Proteobacteria), followed by Corynebacteriaceae (phylum Actinobacteria). Klebsiella was the most dominant genus (78%) and Corynebacterium constituted 9% of the assigned sequences. Scabies mite eggs had a more erse microbial composition with sequences from Proteobacteria being the most dominant (75%), while Actinobacteria, Bacteroidetes and Firmicutes accounted for 23% of the egg microbiome sequences. DNA sequences of a potential endosymbiont, namely Streptomyces , were identified in the metagenome sequence data of both life stages. The presence of Streptomyces was confirmed by conventional PCR. Digital droplet PCR indicated higher Streptomyces numbers in adult mites compared to eggs. Streptomyces were localized histologically in the scabies mite gut and faecal pellets by Fluorescent In Situ Hybridization (FISH). Streptomyces may have essential symbiotic roles in the scabies parasite intestinal system requiring further investigation.
Publisher: Cambridge University Press (CUP)
Date: 10-1994
DOI: 10.1017/S0950268800051736
Abstract: Between 1966 and 1991, melioidosis, a disease caused by Pseudomonas pseudomallei that is mostly confined to tropical regions, occurred in farm animals and a farmer in temperate south-west Western Australia. Using an Escherichia coli probe containing a ribosomal RNA operon, P. pseudomallei DNA from isolates from 8 animals, a soil s le and the human case showed an identical ribotype on Southern blotting. The ribotype was different from the 3 commonest ribotypes seen in tropical Australia. This molecular typing supports the theory of clonal introduction of P. pseudomallei into a non-endemic region, with environmental contamination, local dissemination and persistence over 25 years. As melioidosis is often fatal in humans, such persistence in a temperate region is cause for concern.
Publisher: Oxford University Press (OUP)
Date: 2005
DOI: 10.1086/426443
Abstract: Concern about the emergence of antibiotic-resistant strains and about morbidity and/or mortality related to rheumatic fever and rheumatic heart disease has been a continuous impetus for the development of a safe, effective vaccine against group A Streptococcus (GAS). To date, >120 GAS M types are known, as identified by serological typing. In general, serum immunoglobulin G directed to the hypervariable NH2 terminal portion of M protein leads to complement fixation and opsonophagocytosis of the homologous streptococcal serotype by polymorphonuclear leukocytes, and the protection is type specific. The sequence variation at the N terminus ultimately affects the binding of opsonic antibodies. Because of hypervariability in these opsonic sequences from different M types, it was relevant to use epitopes derived from these multiple sequences in a "multivalent vaccine" design for evaluation of protection against these M types of GAS. Thus, any attempts to design vaccines for a given community will require information on N terminal-sequence typing and variation. In the present study, we performed molecular characterization of isolates recovered from patients in northern India--to our knowledge, for the first time--in an attempt to study the circulating M types and their N terminal sequence variability. We report tremendous ersity in GAS strains recovered from symptomatic patients, with implications on the design of appropriate vaccines. Fifty-nine isolates represented 33 different sequence types. Very few novel types and no predominant clones were found. The high ersity of emm types encountered in a single year suggests that any M protein-based multivalent vaccine would have to be specifically tailored for this region.
Publisher: Microbiology Society
Date: 02-2010
Abstract: Streptococcus pyogenes [group A streptococcus (GAS)], a human pathogen, and Streptococcus dysgalactiae subsp. equisimilis [human group G and C streptococcus (GGS/GCS)] are evolutionarily related, share the same tissue niche in humans, exchange genetic material, share up to half of their virulence-associated genes and cause a similar spectrum of diseases. Yet, GGS/GCS is often considered as a commensal bacterium and its role in streptococcal disease burden is under-recognized. While reports of the recovery of GGS/GCS from normally sterile sites are increasing, studies describing GGS/GCS throat colonization rates relative to GAS in the same population are very few. This study was carried out in India where the burden of streptococcal diseases, including rheumatic fever and rheumatic heart disease, is high. As part of a surveillance study, throat swabs were taken from 1504 children attending 7 municipal schools in Mumbai, India, during 2006–2008. GAS and GGS/GCS were identified on the basis of β -haemolytic activity, carbohydrate group and PYR test, and were subsequently typed. The GGS/GCS carriage rate (166/1504, 11 %) was eightfold higher than the GAS carriage (22/1504, 1.5 %) rate in this population. The 166 GGS/GCS isolates collected represented 21 different emm types (molecular types), and the 22 GAS isolates represented 15 different emm types. Although the rate of pharyngitis associated with GGS/GCS is marginally lower than with GAS, high rates of throat colonization by GGS/GCS underscore its importance in the pathogenesis of pharyngitis.
Publisher: Informa UK Limited
Date: 06-2009
DOI: 10.1586/ERV.09.33
Abstract: Streptococcus pyogenes, commonly referred to as group A streptococcus (GAS), colonizes the epithelial surfaces of the upper respiratory tract and the skin, where it causes a myriad of diseases that vary in clinical presentation and severity. Several candidate GAS vaccines are now approaching or have entered human clinical trials. However, the preclinical evaluation for the leading vaccine candidates has been premised on their ability to induce systemic protection through parenteral immunization. While systemic immunity has proven effective in preventing GAS dissemination and associated disease, it may not prove to be the optimal approach for inducing mucosal immunity against GAS. With this in mind, many researchers are moving toward testing the efficacy of their GAS vaccine candidate when delivered to the mucosal surface. This review discusses the interaction of GAS with the mucosal immune system and the approaches taken thus far in developing a mucosal GAS vaccine.
Publisher: Elsevier BV
Date: 05-2007
DOI: 10.1016/J.VACCINE.2007.01.079
Abstract: Concerns of immune cross-reactivity, between epitopes of the group A streptococcal (GAS) M-proteins and host proteins have hindered the progress of an effective GAS vaccine. An ideal M-protein based subunit vaccine should not elicit heart tissue cross-reactive antibody responses and should not activate M-protein specific CD4+ T-cells. In the current study we used a bioinformatic and immunoinformatic approach to assess the safety of J8 and J14, chimeric vaccine constructs containing a GAS derived M-protein epitope embedded in flanking GCN4 region. We demonstrate that at the primary amino acid level J8 and J14 show very little homology to human proteins. ProPred, RANKPEP and HLABIND algorithms failed to predict significant binding between the M-protein specific regions of J8 and J14 and class II binding alleles. A single peptide was predicted to bind to HLA class I allele B_2705. This data was supported by cellular proliferation assays demonstrating few peripheral blood mononuclear cells (PBMCs) from donors respond to J8 and J14. Reassuringly, there was no correlation between proliferation to these peptides, and proliferation to host proteins. This data suggests that J8 and J14 are unlikely to induce cross-reactive immune responses, and will be safe for use in humans.
Publisher: Elsevier BV
Date: 03-1976
Publisher: Oxford University Press (OUP)
Date: 1987
Abstract: Marfan syndrome is a heritable disorder of the connective tissue that affects many organ systems. However, the most serious complication in patients with Marfan syndrome is progressive aortic root dilation, which may lead to aortic dissection, rupture or aortic regurgitation. Prevention of these life threatening complications is of major importance. We report here a case of a 34-year-old, Caucasian male diagnosed for the first time with Marfan syndrome. He required medical attention due to his chest pain that resulted as a consequence of strenuous physical effort. Medical examinations revealed severe aortic root enlargement and aortic intramural hematoma. Patient ended-up fatally during open heart surgery. It is very important to recognize on time Marfan syndrome, as preventive actions that should be undertaken can avoid its serious consequences.
Publisher: Elsevier BV
Date: 03-2007
DOI: 10.1016/J.MICINF.2006.11.014
Abstract: Group A streptococcus (GAS) is a human pathogen associated with a wide range of human diseases that vary in symptoms and clinical severity. In this report we describe the use of a targeted low density array representing genes encoding classical virulence factors, purported virulence factors and other extracellular proteins to examine differences in the genetic profiles of 68 clinical GAS isolates. Of the 226 genes on the array (encoding 217 virulence factors or putative extracellular proteins and nine positive control house-keeping proteins) 62 had distributions that were statistically associated with specific GAS M-types. While 32 of these genes were bacteriophage related, the remaining 30 have not previously been described as bacteriophage associated. We show that these 'non-bacteriophage related' genes are found in 11 loci located in five greater chromosomal regions, often near classical GAS virulence factors, and often accompanied by genes associated with mobile genetic elements (MGEs). Many of these loci also demonstrated genetic variation within strains of the same M-type, suggesting these regions to be recombinatorial and mutational hotspots. Evidence for acquisition of genes from other species is also apparent in these loci. Our data suggests that imprecise recombination events involving MGEs not only result in acquisition of new genes, but can also result in deletion of flanking chromosomal genes. Thus MGE related events would appear to be the major contributor to variation of discrete virulence loci, which could account for the disease causing propensity of in idual strains. We believe that profiling of the 11 loci could be a meaningful tool in epidemiological GAS typing studies.
Publisher: Elsevier BV
Date: 09-1991
DOI: 10.1016/0147-619X(91)90051-W
Abstract: A 7.5-kb cryptic plasmid is found in all serotypes of the obligate intracellular parasite, Chlamydia trachomatis. Although at least nine open reading frames are apparent from sequence analysis of plasmid DNA, only a small region of approximately 500 bp has been consistently shown to be transcriptionally active by Northern blot analysis. In this study, transcription was analyzed using a host-free system in which RNA synthesized by chlamydiae isolated from host cells was hybridized to different regions of the plasmid. The results suggest that fragments corresponding to all open reading frames are transcribed, but at varied relative levels depending upon the stage of the life cycle. The hybridization patterns also suggested a net chemical degradation of plasmid-specified RNA in a 3' to 5' direction.
Publisher: Bentham Science Publishers Ltd.
Date: 2004
Abstract: Group A streptococcus (GAS) is responsible for a number of diseases ranging from uncomplicated pharyngitis through to life-treating invasive and post-infectious diseases such as necrotizing fasciitis and rheumatic heart disease. GAS associated diseases occur globally and are serious problems in many developing nations and indigenous populations of many developed nations. This, and the resurgence in industrialized countries, and increased virulence of GAS in the 1980s highlight the need of cost-effective control strategies. Here we highlight the GAS diseases that are still a problem in many populations and discuss potentially useful strategies to combat GAS infections and disease.
Publisher: Elsevier BV
Date: 08-2004
Publisher: Elsevier BV
Date: 04-1981
Publisher: MDPI AG
Date: 23-04-2021
DOI: 10.3390/MICROORGANISMS9050907
Abstract: Epidemiological studies link Sarcoptes scabiei infection and impetigo. Scabies mites can promote Streptococcus pyogenes (Group A Streptococcus) and Staphylococcus aureus infections by breaching the skin barrier and excreting molecules that inhibit host innate immune responses. However, little is known about the composition and the function of the scabies-associated microbiota. Here, high-throughput whole-metagenome sequencing was used to explore the scabies-associated microbiome. Scabies mites including their immediate microenvironments were isolated from two patients with severe scabies in Northern Australia. Two ~45–50 million paired-end reads Illumina libraries were generated of which ~2 (5.1%) and 0.7 million (1.3%) microbial reads were filtered out by mapping to human (hg19) and mite draft genomes. Taxonomic profiling revealed a microbial community dominated by the phylum Firmicutes (A: 79% and B: 59%) and genera that comprise Streptococcus, Staphylococcus, Acinetobacter, and Corynebacterium. Assembly of the metagenome reads resulted in genome bins representing reference genomes of Acinetobacter baumannii, Streptococcus dysgalactiae (Group C/G), Proteus mirablis and Staphylococcus aureus. The contigs contained genes relevant to pathogenicity and antibiotics resistance. Confocal microscopy of a patient skin s le confirmed A. baumannii, Streptococci and S. aureus in scabies mite gut and faeces and the surrounding skin. The study provides fundamental evidence for the association of opportunistic pathogens with scabies infection.
Publisher: Public Library of Science (PLoS)
Date: 09-03-2017
Publisher: American Society for Microbiology
Date: 12-2004
DOI: 10.1128/IAI.72.12.7342-7345.2004
Abstract: Fibronectin binding protein F1 (Sfb1) of Streptococcus pyogenes (group A streptococcus [GAS]) is a well-characterized adhesin that has been shown to induce protection in mice against a lethal intranasal GAS challenge after intranasal immunization with cholera toxin B subunit (CTB) as adjuvant. With a murine skin infection model, we have shown that Sfb1/CTB vaccination neither elicits opsonizing antibodies nor prevents systemic bacterial growth and dissemination to internal organs after a subcutaneous GAS challenge. These results indicate that an Sfb1-based vaccine should be complemented with additional protective antigens in order to be used in areas such as the tropical north of Australia, where the skin is the primary route of entry for invasive streptococcal diseases.
Publisher: Wiley
Date: 09-1994
Abstract: A method preserving the activity of the erythrocytic enzyme delta-aminolevulinic acid dehydratase (EC 4.2.1.24) was developed using a vehicle of 50% aqueous glycerol containing dithiothreitol (80 microM). Whole heparinized blood (0.5 ml) was added to 0.75 ml of this mixture in a cryovial tube (capacity 1.3 ml), mixed well and stored in a freezer at -20 degrees C for 21 days. Statistical comparison of the enzyme activity when freshly assayed and after storage indicated excellent agreement for quantitation of the non-activated enzyme (intraclass correlation coefficient = 0.99) and the activated enzyme (intraclass correlation coefficient = 0.98). This storage method will facilitate future population studies on lead intoxication, particularly those in remote locations.
Publisher: American Society for Microbiology
Date: 04-2007
DOI: 10.1128/JB.01590-06
Abstract: Streptococcus dysgalactiae subsp. equisimilis strains (group G streptococcus [GGS]) are largely defined as commensal organisms, which are closely related to the well-defined human pathogen, the group A streptococcus (GAS). While lateral gene transfers are emerging as a common theme in these species, little is known about the mechanisms and role of these transfers and their effect on the population structure of streptococci in nature. It is now becoming evident that bacteriophages are major contributors to the genotypic ersity of GAS and, consequently, are pivotal to the GAS strain structure. Furthermore, bacteriophages are strongly associated with altering the pathogenic potential of GAS. In contrast, little is know about phages from GGS and their role in the population dynamics of GGS. In this study we report the first complete genome sequence of a GGS phage, Φ3396. Exhibiting high homology to the GAS phage Φ315.1, the chimeric nature of Φ3396 is unraveled to reveal evidence of extensive ongoing genetic ersity and dissemination of streptococcal phages in nature. Furthermore, we expand on our recent findings to identify inducible Φ3396 homologues in GAS from a region of endemicity for GAS and GGS infection. Together, these findings provide new insights into not only the population structure of GGS but also the overall population structure of the streptococcal genus and the emergence of pathogenic variants.
Publisher: Wiley
Date: 03-1993
DOI: 10.1111/J.1365-2958.1993.TB01185.X
Abstract: Extracts of Chlamydia psittaci and Chlamydia trachomatis were used to transcribe molecularly cloned chlamydial genes in vitro. The extracts were prepared by lysing reticulate bodies, obtaining the 10,000 x g centrifugation pellet, and eluting RNA polymerase from the pellet by treatment with 2M KCl to yield a fraction designated SS2. Some in vitro transcription was initiated from non-chlamydial promoters and a small amount of transcription was from endogenous DNA template in SS2. However, optimal transcription from exogenous templates required chlamydial promoter sequences, and primer extension analysis indicated that chlamydia promoter-specific in vitro transcription was initiated from the same start sites recognized in vivo. A monoclonal antibody that was generated against Escherichia coli sigma 70 and which immunologically cross-reacts with C. trachomatis sigma 66 inhibited in vitro transcription of vector and cloned chlamydial DNA, suggesting that transcriptional initiation in the SS2 fraction is mediated by sigma 66. An in vitro transcription assay based on detection of transcripts of specific lengths was applied to the chlamydial system this assay and others described here should be useful in defining chlamydial promoters and other transcriptional regulatory elements.
Publisher: Springer Science and Business Media LLC
Date: 03-1987
DOI: 10.1007/BF00344034
Abstract: Aeromonas hydrophila is a serious pathogen and can cause hemorrhagic septicemia in fish. To control this disease, antibiotics and chemicals are widely used which can consequently result in "superbugs" and chemical accumulation in the food chain. Though vaccine against A. hydrophila is available, its use is limited due to multiple serotypes of this pathogen and problems of safety and efficacy. Another problem with vaccination is the ability to apply it to small fish especially in high numbers. In this study, we tried a new way to attenuate the A. hydrophila infection by using a quorum quenching strategy with a recombinant AHL-lactonase expressed in Pichia pastoris. The AHL-lactonase (AiiAB546) from Bacillus sp. B546 was produced extracellularly in P. pastoris with a yield of 3,558.4 +/- 81.3 U/mL in a 3.7-L fermenter when using 3-oxo-C8-HSL as the substrate. After purification with a HiTrap Q Sepharose column, the recombinant homogenous protein showed a band of 33.6 kDa on SDS-PAGE, higher than the calculated molecular mass (28.14 kDa). Deglycosylation of AiiAB546 with Endo H confirmed the occurrence of N-glycosylation. The purified recombinant AiiAB546 showed optimal activity at pH 8.0 and 20 degrees C, exhibited excellent stability at pH 8.0-12.0 and thermal stability at 70 degrees C, was firstly confirmed to be significantly protease-resistant, and had wide substrate specificity. In application test, when co-injected with A. hydrophila in common carp, recombinant AiiAB546 decreased the mortality rate and delayed the mortality time of fish. Our results not only indicate the possibility of mass-production of AHL-lactonase at low cost, but also open up a promising foreground of application of AHL-lactonase in fish to control A. hydrophila disease by regulating its virulence. To our knowledge, this is the first report on heterologous expression of AHL-lactonase in P. pastoris and attenuating A. hydrophila virulence by co-injection with AHL-lactonase.
Publisher: American Society for Microbiology
Date: 11-2002
Publisher: Springer Science and Business Media LLC
Date: 03-1987
DOI: 10.1007/BF00344033
Abstract: Work related stress is associated with a range of debilitating health outcomes. However, no unanimously accepted assessment tool exists for the early identification of in iduals suffering from chronic job stress. The psychological concept of self-perceived stress reactivity refers to the in idual disposition of a person to answer stressors with immediate as well as long lasting stress reactions, and it could be a valid indicator of current as well as prospective adverse health outcomes. The aim of this study was to determine the extent to which perceived stress reactivity correlates with various parameters of psychosocial health, cardiovascular risk factors, and parameters of chronic stress and job stress in a s le of middle-aged industrial employees in a so-called "sandwich-position". In this cross-sectional study, a total of 174 industrial employees were assessed for psychosocial and biological stress parameters. Differences between groups with high and low stress reactivity were analysed. Logistic regression models were applied to identify which parameters allow to predict perceived high versus low stress reactivity. In our s le various parameters of psychosocial stress like chronic stress and effort-reward imbalance were significantly increased in comparison to the normal population. Compared to employees with perceived low stress reactivity, those with perceived high stress reactivity showed poorer results in health-related complaints, depression, anxiety, sports behaviour, chronic stress, and effort-reward imbalance. The educational status of employees with perceived low stress reactivity is higher. Education, cardiovascular complaints, chronic stress, and effort-reward imbalance were moderate predictors for perceived stress reactivity. However, no relationship was found between stress reactivity and cardiovascular risk factors in our s le. Job stress is a major burden in a relevant subgroup of industrial employees in a middle management position. Self-perceived stress reactivity seems to be an appropriate concept to identify employees who experience psychosocial stress and associated psychological problems at the workplace.
Publisher: Elsevier BV
Date: 09-1981
DOI: 10.1016/0022-2836(81)90002-4
Abstract: Impulsivity is regarded as a multifaceted construct that comprises two dimensions: rapid-response impulsivity and reward-delay impulsivity. It is unclear, however, which aspects of trait impulsivity, as assessed by self-report measures are related to rapid-response impulsivity and/or to reward-delay impulsivity, as different results have been reported in studies using both self-report and cognitive measures. This study aimed to directly relate self-report measures of impulsivity to cognitive measures of impulsivity in in iduals at low- or high-levels on two impulsivity dimensions, specifically rapid-response impulsivity and reward-delay impulsivity. Participants were classified into high- or low-impulsivity groups based on (1) level of rapid-response impulsivity (determined by BIS-11 Motor subscale scores) (2) level of reward-delay impulsivity (determined by BIS/BAS subscale scores) and (3) a combination of rapid-response impulsivity and reward-delay impulsivity levels. Impulsivity was assessed using Go/No-Go, Stop-Signal and Delay-Discounting tasks and self-report measures. The high rapid-response impulsivity group showed significantly higher reward-delay impulsivity on both, the Delay-Discounting tasks and on self-report measures assessing reward-delay impulsivity, than the low-risk group. Based on the level of reward-delay impulsivity, the high reward-delay impulsivity group scored significantly higher on task-based (cognitive) and self-report measures assessing rapid-response inhibition than the low reward-delay impulsivity group. Combining both dimensions of impulsivity showed that the high-impulsivity group performed significantly worse in rapid-response paradigms and temporally discounted significantly more impulsively than the low-impulsivity group. Thus, combined impulsivity factors provide better assessment of impulsivity than each dimension alone. In conclusion, robust differences in impulsivity can be identified in non-clinical young adults.
Publisher: Wiley
Date: 10-2016
Publisher: Elsevier BV
Date: 04-2006
Publisher: American Physiological Society
Date: 10-2019
DOI: 10.1152/PHYSREV.00018.2018
Abstract: The importance of the gut-brain axis in maintaining homeostasis has long been appreciated. However, the past 15 yr have seen the emergence of the microbiota (the trillions of microorganisms within and on our bodies) as one of the key regulators of gut-brain function and has led to the appreciation of the importance of a distinct microbiota-gut-brain axis. This axis is gaining ever more traction in fields investigating the biological and physiological basis of psychiatric, neurodevelopmental, age-related, and neurodegenerative disorders. The microbiota and the brain communicate with each other via various routes including the immune system, tryptophan metabolism, the vagus nerve and the enteric nervous system, involving microbial metabolites such as short-chain fatty acids, branched chain amino acids, and peptidoglycans. Many factors can influence microbiota composition in early life, including infection, mode of birth delivery, use of antibiotic medications, the nature of nutritional provision, environmental stressors, and host genetics. At the other extreme of life, microbial ersity diminishes with aging. Stress, in particular, can significantly impact the microbiota-gut-brain axis at all stages of life. Much recent work has implicated the gut microbiota in many conditions including autism, anxiety, obesity, schizophrenia, Parkinson’s disease, and Alzheimer’s disease. Animal models have been paramount in linking the regulation of fundamental neural processes, such as neurogenesis and myelination, to microbiome activation of microglia. Moreover, translational human studies are ongoing and will greatly enhance the field. Future studies will focus on understanding the mechanisms underlying the microbiota-gut-brain axis and attempt to elucidate microbial-based intervention and therapeutic strategies for neuropsychiatric disorders.
Publisher: Elsevier BV
Date: 05-1995
Abstract: The prevalence of rheumatic heart disease (RHD) in Northern Territory Aboriginal communities is high, but there is a low isolation rate of historically rheumatic fever associated M types (such as M5) of group A streptococci (GAS). Many isolates are M non-typable (MNT). Serology suggests that the population is exposed to M5-like isolates some RHD patients having high IgM or IgG titres to two M5 B-repeat region peptide epitopes, B1 (KQQESK) and B4 (EQKSKQ). To identify relatives of M5 in our collection of GAS, oligonucleotide probes to the B1 and B4-repeat regions shared by M5 and a local M5-like isolate, were used to screen 101 isolates for the presence of signature sequences. In all, 28% of the tropical Australian isolates contained the signature sequences, identifying members of the M5 family. The 5' region of the genes for M proteins from three members of the M5 family fell into two sequence types. Hybridisation to probes based on these sequences suggested that among tropical Australian isolates there are at least three distinct sequence types that contained the M5 signature sequences. These results suggest that a considerable number of M5 family GAS are circulating in tropical Australia.
Publisher: Microbiology Society
Date: 1970
DOI: 10.1099/00221287-60-1-125
Abstract: Evidence based virtual environments (VEs) that incorporate compensatory strategies such as cueing may change motor behavior and increase exercise intensity while also being engaging and motivating. The purpose of this study was to determine if persons with Parkinson's disease and aged matched healthy adults responded to auditory and visual cueing embedded in a bicycling VE as a method to increase exercise intensity. We tested two groups of participants, persons with Parkinson's disease (PD) (n = 15) and age-matched healthy adults (n = 13) as they cycled on a stationary bicycle while interacting with a VE. Participants cycled under two conditions: auditory cueing (provided by a metronome) and visual cueing (represented as central road markers in the VE). The auditory condition had four trials in which auditory cues or the VE were presented alone or in combination. The visual condition had five trials in which the VE and visual cue rate presentation was manipulated. Data were analyzed by condition using factorial RMANOVAs with planned t-tests corrected for multiple comparisons. There were no differences in pedaling rates between groups for both the auditory and visual cueing conditions. Persons with PD increased their pedaling rate in the auditory (F 4.78, p = 0.029) and visual cueing (F 26.48, p < 0.000) conditions. Age-matched healthy adults also increased their pedaling rate in the auditory (F = 24.72, p < 0.000) and visual cueing (F = 40.69, p < 0.000) conditions. Trial-to-trial comparisons in the visual condition in age-matched healthy adults showed a step-wise increase in pedaling rate (p = 0.003 to p < 0.000). In contrast, persons with PD increased their pedaling rate only when explicitly instructed to attend to the visual cues (p < 0.000). An evidenced based cycling VE can modify pedaling rate in persons with PD and age-matched healthy adults. Persons with PD required attention directed to the visual cues in order to obtain an increase in cycling intensity. The combination of the VE and auditory cues was neither additive nor interfering. These data serve as preliminary evidence that embedding auditory and visual cues to alter cycling speed in a VE as method to increase exercise intensity that may promote fitness.
Publisher: Oxford University Press (OUP)
Date: 15-05-2006
DOI: 10.1086/503424
Abstract: Genital ulcer disease (GUD) is commonly caused by pathogens for which suitable therapies exist, but clinical and laboratory diagnoses may be problematic. This collaborative project was undertaken to address the need for a rapid, economical, and sensitive approach to the detection and diagnosis of GUD using noninvasive techniques to s le genital ulcers. The genital ulcer disease multiplex polymerase chain reaction (GUMP) was developed as an inhouse nucleic acid lification technique targeting serious causes of GUD, namely, herpes simplex viruses (HSVs), H. ducreyi, Treponema pallidum, and Klebsiella species. In addition, the GUMP assay included an endogenous internal control. Amplification products from GUMP were detected by enzyme linked licon hybridization assay (ELAHA). GUMP-ELAHA was sensitive and specific in detecting a target microbe in 34.3% of specimens, including 1 detection of HSV-1, three detections of HSV-2, and 18 detections of T. pallidum. No H. ducreyi has been detected in Australia since 1998, and none was detected here. No Calymmatobacterium (Klebsiella) granulomatis was detected in the study, but there were 3 detections during ongoing diagnostic use of GUMP-ELAHA in 2004 and 2005. The presence of C. granulomatis was confirmed by restriction enzyme digestion and nucleotide sequencing of the 16S rRNA gene for phylogenetic analysis. GUMP-ELAHA permitted comprehensive detection of common and rare causes of GUD and incorporated noninvasive s ling techniques. Data obtained by using GUMP-ELAHA will aid specific treatment of GUD and better define the prevalence of each microbe among at-risk populations with a view to the eradication of chancroid and donovanosis in Australia.
Publisher: Public Library of Science (PLoS)
Date: 03-08-2011
Publisher: Elsevier BV
Date: 11-2009
DOI: 10.1016/J.VACCINE.2009.08.049
Abstract: A conformationally restricted B cell epitope has been identified as a potential safe vaccine candidate from the major group A streptococcal virulence factor, the M protein. To maintain alpha-helical secondary structure, the minimal epitope is flanked with heterologous sequences to produce the chimeric vaccine candidate called J14. As a strategy toward developing an affordable multivalent GAS vaccine, we have expressed J14 recombinantly with a second GAS protective antigen H12 (rJ14H12). When administered to mice sub-cutaneously, the fusion protein stimulated a strong serum IgG response to the H12 component, but J14 was poorly immunogenic. To increase the immunogenicity of J14 when expressed with the model fusion partner, amino acid modifications were made to the initial recombinant J14 construct to produce rJJo. These changes stabilised the alpha-helical conformation of the recombinant antigen as assessed by circular dichroism. Mice immunised with rJJoH12, the fusion protein incorporating JJo, effectively stimulated a humoral response to both of the included antigens. These data support the feasibility of developing a multivalent vaccine incorporating the conformationally restricted protective antigen J14.
Publisher: Elsevier BV
Date: 03-1989
DOI: 10.1016/0735-0651(89)90023-X
Abstract: A general and sensitive detection method of target DNA is described. The system is based on an oligonucleotide probe labeled to high specific activity. This involves a novel oligonucleotide design incorporating at the 3' end a hairpin structure, allowing extension by polymerase reaction.
Publisher: Elsevier BV
Date: 06-1976
Publisher: Springer Science and Business Media LLC
Date: 09-1983
DOI: 10.1007/BF02101636
Abstract: The pathogenesis of systemic lupus erythematosus (SLE) remains elusive. It appears that serum lipid metabolism is aberrant in SLE patients. Determination of lipid profiles in the serum of SLE patients may provide insights into the underlying mechanism(s) leading to SLE and may discover potential biomarkers for early diagnosis of SLE. This study aimed to identify and quantify the profile of serum lipids in SLE patients (
Publisher: Elsevier BV
Date: 04-2006
Publisher: Springer Science and Business Media LLC
Date: 06-05-2013
Abstract: Group A streptococcus (GAS) is an etiological agent for the immune mediated sequela post streptococcal glomerulonephritis (PSGN). In some populations PSGN is recognized as a risk factor for chronic kidney disease (CKD) and end-stage renal disease (ESRD). It was found that a significantly greater proportion of subjects with past history of PSGN than without the history exhibited seroreactions to streptococcal antigens called streptococcal inhibitor of complement (SIC) and to distantly related SIC (DRS). These antigens are expressed by major PSGN-associated GAS types. We therefore predicted that in populations such as India, which is endemic for streptococcal diseases and which has high prevalence of CKD and ESRD, greater proportions of CKD and ESRD patients exhibit seroreaction to SIC and DRS than healthy controls. To test this we conducted a SIC and DRS seroprevalence study in subjects from Mumbai area. We recruited 100 CKD, 70 ESRD and 70 healthy in iduals. Nineteen and 35.7% of CKD and ESRD subjects respectively were SIC antibody-positive, whereas only 7% of healthy cohort was seropositive to SIC. Furthermore, significantly greater proportion of the ESRD patients than the CKD patients is seropositive to SIC (p=0.02 odds ratio 2.37). No association was found between the renal diseases and DRS-antibody-positivity. Past infection with SIC-positive GAS is a risk factor for CKD and ESRD in Mumbai population. Furthermore, SIC seropositivity is predictive of poor prognosis of CKD patients.
Publisher: American Society for Microbiology
Date: 08-2015
DOI: 10.1128/CVI.00275-15
Abstract: The disease spectrum caused by Streptococcus dysgalactiae subsp. equisimilis resembles that of S. pyogenes (group A streptococcus [GAS]). These two bacterial species are closely related and possess many common virulence characteristics. While some GAS strains express virulence factors called streptococcal inhibitor of complement (SIC) and distantly related to SIC (DRS), some S. dysgalactiae subsp. equisimilis isolates express an orthologue of DRS, which is referred to as DRS-G. We reported previously that seropositivity for either anti-SIC or anti-DRS antibodies (Abs) is associated with poststreptococcal glomerulonephritis (PSGN). However, only seropositivity for anti-SIC Abs is associated with chronic kidney disease (CKD). We now extend the study to test whether seropositivity for anti-DRS-G Abs is also associated with these renal diseases. Stored serum s les collected for our previous study were tested by an enzyme-linked immunosorbent assay (ELISA) for Abs to DRS-G. The s les represented sera from 100 CKD adult patients, 70 adult end-stage renal disease (ESRD) patients, 25 PSGN pediatric patients, and corresponding age-matched control subjects. The proportion of PSGN, CKD, and ESRD patients who showed seroreaction to anti-DRS-G Abs was significantly higher than that of the corresponding age-matched controls, who in general exhibited seropositivity rates commensurate with the isolation rate of drsG -positive S. dysgalactiae subsp. equisimilis in the community during this study period. Since higher rates of seropositivity for anti-DRS-G Abs in the renal disease categories are resultant of previous infections with DRS-G-positive S. dysgalactiae subsp. equisimilis strains, we conclude the seropositivity is an additional risk factor for these renal diseases. In this regard, anti-DRS-G Abs have attributes similar to those of the anti-SIC Abs.
Publisher: American Society for Microbiology
Date: 06-2014
DOI: 10.1128/IAI.01411-13
Abstract: SIC and DRS are related proteins present in only 4 of the Streptococcus pyogenes emm types. These proteins inhibit complement-mediated lysis and/or the activity of certain antimicrobial peptides (AMPs). A gene encoding a homologue of these proteins, herein called DrsG, has been identified in the related bacterium Streptococcus dysgalactiae subsp. equisimilis . Here we show that geographically dispersed isolates representing 14 of 50 emm types examined possess variants of drsG . However, not all isolates within the drsG -positive emm types possess the gene. Sequence comparisons also revealed a high degree of conservation in different S. dysgalactiae subsp. equisimilis emm types. To examine the biological activity of DrsG, recombinant versions of two major DrsG variants, DrsGS and DrsGL, were expressed and purified. Western blot analysis using antisera raised to these proteins demonstrated both variants to be expressed and secreted into culture supernatants. Unlike SIC, but similar to DRS, DrsG does not inhibit complement-mediated lysis. However, like both SIC and DRS, DrsG is a ligand of the cathelicidin LL-37 and is inhibitory to its bactericidal activity in in vitro assays. Conservation of prolines in the C-terminal region also suggests that these residues are important in the biology of this family of proteins. This is the first report demonstrating the activity of an AMP-inhibitory protein in S. dysgalactiae subsp. equisimilis and suggests that inhibition of AMP activity is the primary function of this family of proteins. The acquisition of the complement-inhibitory activity of SIC may reflect its continuing evolution.
Publisher: American Society for Microbiology
Date: 07-2002
DOI: 10.1128/JCM.40.7.2642-2644.2002
Abstract: Streptococcus pyogenes isolates from a tropical region and a subtropical region of Australia with high and low incidences of severe streptococcal diseases, respectively, were analyzed for speA , speB , and speC gene distributions and NAD-glycohydrolase expression. No direct correlation of these characteristics with a propensity to cause invasive diseases was observed.
Publisher: Elsevier BV
Date: 04-1981
DOI: 10.1016/0027-5107(81)90030-0
Abstract: Intra-species fusion products of Saccharomyces cerevisiae, Saccharomyces unisporus and Torulopsis glabrata have been isolated following polyethylene glycol-induced fusion of protoplasts and selection for prototrophic colonies. Staining with lomofungin showed that all fusion products were uninucleate. Measurement of DNA content mostly gave values between haploid and diploid levels indicating that the majority of fusion products were aneuploid, Nevertheless fusion products of S. cerevisiae and S. unisporus were, as expected, more resistant to X-irradiation than their haploid parents. By contrast, the X-ray dose-response curve of all T. glabrata fusion products was indistinguishable from their progenitors despite the fact that mitotic segregants could be recovered amongst the survivors to X-rays. A possible explanation for the behaviour towards X-rays of T. glabrata fusion products is that this species lacks a DNA repair pathway involving recombination between homologous chromosomes. We conclude from this study that the shape of the X-ray dose-response curve should not be taken to indicate the ploidy of new yeast isolates without supporting data.
Publisher: American Society for Microbiology
Date: 12-2003
DOI: 10.1128/JCM.41.12.5398-5406.2003
Abstract: Streptococcal fibronectin-binding protein is an important virulence factor involved in colonization and invasion of epithelial cells and tissues by Streptococcus pyogenes . In order to investigate the mechanisms involved in the evolution of sfbI , the sfbI genes from 54 strains were sequenced. Thirty-four distinct alleles were identified. Three principal mechanisms appear to have been involved in the evolution of sfbI . The amino-terminal aromatic amino acid-rich domain is the most variable region and is apparently generated by intergenic recombination of horizontally acquired DNA cassettes, resulting in a genetic mosaic in this region. Two distinct and ergent sequence types that shared only 61 to 70% identity were identified in the central proline-rich region, while variation at the 3′ end of the gene is due to deletion or duplication of defined repeat units. Potential antigenic and functional variabilities in SfbI imply significant selective pressure in vivo with direct implications for the microbial pathogenesis of S. pyogenes .
Publisher: Elsevier BV
Date: 08-2000
Publisher: Elsevier BV
Date: 04-2006
Publisher: Springer Science and Business Media LLC
Date: 09-1983
DOI: 10.1007/BF02101637
Abstract: Atherosclerosis is a progressive pathological remodeling of the arteries and one of its hallmarks is the presence of chronic inflammation. Notably, there is an increased proportion and activation state of specific monocyte subsets in systemic blood circulation. Monocyte subsets have distinct contributions to the formation, progression, and destabilization of the atherosclerotic plaque. Strong clinical and epidemiological studies show that regular aerobic exercise mitigates the progression of cardiovascular disease. In fact, aerobic fitness is a powerful predictor of cardiovascular mortality in adults, independent of traditional risk factors such as hypertension and hyperlipidemia. Acute bouts and chronic exercise training modulate monocyte behavior, ranging from their recruitment from the bone marrow or marginal pool, to tissue margination and functional changes in cytokine and chemokine production. Such modulation could reflect a potential mechanism for the cardio-protective effect of exercise on atherosclerosis. This review summarizes the current knowledge of monocyte subsets and highlights what is known about their responses to exercise.
Publisher: American Society for Microbiology
Date: 15-11-2004
DOI: 10.1128/JB.186.22.7601-7609.2004
Abstract: The group A Streptococcus (GAS) is an important pathogen that is responsible for a wide range of human diseases. Fibronectin binding proteins (FBPs) play an important role in promoting GAS adherence and invasion of host cells. The prtF2 gene encodes an FBP and is present in approximately 60% of GAS strains. In the present study we examined 51 prtF2 -positive GAS strains isolated from the Northern Territory of Australia, and here we describe two genotypes of prtF2 which are mutually exclusive. The two genotypes have been identified previously as pfbp and fbaB . We show that these genotypes map to the same chromosomal location within the highly recombinatorial fibronectin-collagen-T antigen (FCT) locus, indicating that they arose from a common ancestor, and in this study these genotypes were designated the pfbp type and the fbaB type. Phylogenetic analysis of seven pfbp types, 14 fbaB types, and 11 prtF2 -negative GAS strains by pulsed-field gel electrophoresis (PFGE) produced 32 distinct PFGE patterns. Interpretation of evolution based on the PFGE dendrogram by parsimony suggested that the pfbp type had a recent origin compared to the fbaB type. A comparison of multiple DNA sequences of the pfbp and fbaB types revealed a mosaic pattern for the amino-terminal region of the pfbp types. The fbaB type is generally conserved at the amino terminus but varies in the number of fibronectin binding repeats in the carboxy terminus. Our data also suggest that there is a possible association of the pfbp genotype with sof (84.2%), while the fbaB genotype was found in a majority of the GAS strains negative for sof (90.6%), indicating that these two prtF2 subtypes may be under different selective pressures.
Publisher: Oxford University Press (OUP)
Date: 24-09-2019
Publisher: American Society for Microbiology
Date: 04-2009
DOI: 10.1128/JB.01624-08
Abstract: Lateral gene transfer is a significant contributor to the ongoing evolution of many bacterial pathogens, including β-hemolytic streptococci. Here we provide the first characterization of a novel integrative conjugative element (ICE), ICE Sde 3396, from Streptococcus dysgalactiae subsp. equisimilis (group G streptococcus [GGS]), a bacterium commonly found in the throat and skin of humans. ICE Sde 3396 is 64 kb in size and encodes 66 putative open reading frames. ICE Sde 3396 shares 38 open reading frames with a putative ICE from Streptococcus agalactiae (group B streptococcus [GBS]), ICE Sa 2603. In addition to genes involves in conjugal processes, ICE Sde 3396 also carries genes predicted to be involved in virulence and resistance to various metals. A major feature of ICE Sde 3396 differentiating it from ICE Sa 2603 is the presence of an 18-kb internal recombinogenic region containing four unique gene clusters, which appear to have been acquired from streptococcal and nonstreptococcal bacterial species. The four clusters include two cadmium resistance operons, an arsenic resistance operon, and genes with orthologues in a group A streptococcus (GAS) prophage. Streptococci that naturally harbor ICE Sde 3396 have increased resistance to cadmium and arsenate, indicating the functionality of genes present in the 18-kb recombinogenic region. By marking ICE Sde 3396 with a kanamycin resistance gene, we demonstrate that the ICE is transferable to other GGS isolates as well as GBS and GAS. To investigate the presence of the ICE in clinical streptococcal isolates, we screened 69 isolates (30 GGS, 19 GBS, and 20 GAS isolates) for the presence of three separate regions of ICE Sde 3396. Eleven isolates possessed all three regions, suggesting they harbored ICE Sde 3396-like elements. Another four isolates possessed ICE Sa 2603-like elements. We propose that ICE Sde 3396 is a mobile genetic element that is capable of acquiring DNA from multiple bacterial sources and is a vehicle for dissemination of this DNA through the wider β-hemolytic streptococcal population.
Publisher: OMICS Publishing Group
Date: 06-2011
DOI: 10.4066/AMJ.2011.650
Publisher: Elsevier BV
Date: 06-2010
DOI: 10.1016/J.TIM.2010.02.007
Abstract: Interaction of the M-protein of group A Streptococcus (GAS) with its numerous host binding partners might assist the bacteria in evading host immune responses. Although the extensive ersity of this protein has been highlighted by different GAS typing schemes, most of the structural and functional information has been obtained from a limited number of types. Increasing numbers of epidemiological, clinical and biological reports suggest that the structure and function of the M protein is less conserved than previously thought. This review focuses on the known interactions between M proteins and host ligand proteins, emphasizing that our understanding of this well-studied molecule is fragmented.
Publisher: Oxford University Press (OUP)
Date: 10-2000
DOI: 10.1086/315842
Abstract: Disease caused by group A streptococci (GAS) in tropical regions often takes the form of impetigo, whereas pharyngitis tends to predominate in temperate zones. GAS derived from asymptomatic throat infections and pyoderma lesions of rural Aboriginal Australians were evaluated for phylogenetic distant emm genes, which represent ecological markers for tissue site preference. On the basis of the percentage of total isolates from a given tissue, emm pattern A-C organisms exhibited a stronger predilection for the throat, whereas pattern D organisms preferred the skin. Only 16% of isolates collected by active surveillance displayed pattern A-C, which reflects the low incidence of oropharyngeal infection. Importantly, most (70%) pattern A-C organisms were isolated from skin sores, despite their innate tendency to infect the throat. Combined with findings from nontropical populations, analysis of the data supports the hypothesis that GAS tissue preferences are genetically predetermined and that host risk factors for infection strongly influence the differential reproduction of in idual clones.
Publisher: Springer Science and Business Media LLC
Date: 03-03-2015
Publisher: Elsevier BV
Date: 05-1996
Abstract: Previously we described a long-polymerase chain reaction (PCR) method to lify a 4-7 kb target containing most of the components of the vir regulon (mga, emm-like genes and scpA) in a number of group A streptococcus (GAS) isolates. In contrast to GAS, strains of human group G streptococcus (GGS) gave approximately 1.6 or 1.8 kb products. Sequence analysis of the lified products issued from GGS templates revealed a mosaic consisting of upstream sequence from mga (the gene for positive regulator of vir regulon), an unidentified open reading frame, a short segment of emm (the gene for M protein, an antiphagocytic molecule) and an upstream sequence of scp (C5a-peptidase gene). A full length scpG is present immediately downstream from the mosaic segment in the human GGS genome. The GGS PCR fragment did not code for mga or full length emm. All human GGS isolates are known to code for emm but the gene is separated from scpG by at least 10 kb. Our data, obtained using long-PCR and unrelated strains of GGS, confirm this. We could not detect a homologue of mga in human GGS by hybridization analysis. The mosaic sequence suggests that enbloc transfer of the vir regulon from GAS to a GGS progenitor may have occurred, following which deletion and rearrangement events may have taken place. Partial nucleotide sequences of emm corresponding to the variable domain of M proteins from three local GGS isolates were determined. One sequence (emmGGS6) is 99% identical to emm from a geographically separated isolate of GGS recently described.3 emmGGS6 also has significant homology with emm from a GAS strain (STDONALD) isolated from the same geographical area as was GGS6. The two emm sequences (emmGGS6 and emmSTDONALD) revealed frameshift-compensatory frameshift mutations relative to each other, contributing to lower amino acid homology between the two predicted M proteins. Since emmSTDONALD has no known relatives within the 80 or so emm sequences in the database, we speculate that it could have been laterally acquired from GGS. Horizontal transfers between GGS and GAS may be ongoing.
Publisher: Oxford University Press (OUP)
Date: 09-12-2017
Abstract: Acute rheumatic fever and rheumatic heart disease (ARF/RHD) have long been described as autoimmune sequelae of Streptococcus pyogenes or group A streptococcal (GAS) infection. Both antibody and T-cell responses against immunodominant GAS virulence factors, including M protein, cross-react with host tissue proteins, triggering an inflammatory response leading to permanent heart damage. However, in some ARF/RHD-endemic regions, throat carriage of GAS is low. Because Streptococcus dysgalactiae subspecies equisimilis organisms, also known as β-hemolytic group C streptococci and group G streptococci (GGS), also express M protein, we postulated that streptococci other than GAS may have the potential to initiate or exacerbate ARF/RHD. Using a model initially developed to investigate the uniquely human disease of ARF/RHD, we have discovered that GGS causes interleukin 17A/interferon γ-induced myocarditis and valvulitis, hallmarks of ARF/RHD. Remarkably the histological, immunological, and functional changes in the hearts of rats exposed to GGS are identical to those exposed to GAS. Furthermore, antibody cross-reactivity to cardiac myosin was comparable in both GGS- and GAS-exposed animals, providing additional evidence that GGS can induce and/or exacerbate ARF/RHD.
Publisher: Oxford University Press (OUP)
Date: 1994
DOI: 10.1093/NAR/22.3.534
Abstract: The aim of this study was to determine and compare test-retest variability (TRV) of the computerised visual acuity (VA) COMPlog system on participants with normal vision and non-normal vision induced by bangerter foils (BFs). Twenty adult volunteers with VA of 0.100 logMAR or better in each eye and no eye conditions were included. Monocular VA data using the COMPlog system under five conditions-with plain Plano glasses (visually normal condition) and four pairs of Plano glasses with BF strengths of 0.6, 0.3, 0.2 and 0.1 (induced non-normal vision conditions)-were collected on two separate visits. To reduce bias, the eye tested and order of the BFs assessed were randomised. Data comparison was analysed using 2-factor ANOVA and paired t-tests and Bland Altman analysis to assess TRV. Mean VA score from the two visits was -0.072 ± 0.1 logMAR for Plano, 0.106 ± 0.1 logMAR for BF 0.6, 0.428 ± 0.1 logMAR for BF 0.3, 0.662 ± 0.09 logMAR for BF 0.2 and 0.850 ± 0.08 logMAR for BF 0.1. As BF density increased, VA score significantly worsened (p < 0.0001). Overall mean VA score from the first and second visit was 0.410 ± 0.4 logMAR and 0.379 ± 0.4 logMAR, respectively. This improvement was significant (p < 0.009). The 95% limits of agreement of the VA scores between testing conditions had a range of ±0.120 to ±0.220 logMAR. Increase in BF strength led to a worsened VA score. However, the COMPlog TRV under the visually normal and induced non-normal vision conditions were within a similar range (±0.120 to ±0.220 logMAR). VA significantly improved on the second visit, suggesting a possible learning effect, which could have a clinical impact.
Publisher: Elsevier BV
Date: 12-1989
Publisher: American Society for Microbiology
Date: 08-2003
DOI: 10.1128/JCM.41.8.3936-3938.2003
Abstract: Epidemiologically unrelated Streptococcus pyogenes strains isolated from blood, throat, and skin were assayed for adherence to HEp2 and HaCaT cells. Invasive isolates showed significantly higher avidity for these cell lines than isolates from skin and throat. In general, S. pyogenes showed greater binding to HaCaT cells than to HEp2 cells.
Publisher: Wiley
Date: 10-1991
DOI: 10.1111/J.1365-2915.1991.TB00573.X
Abstract: DNA probes have been constructed to distinguish between the members of the Anopheles farauti complex of mosquitoes known as species numbers 1, 2 and 3. Partial genomic libraries of the three known species were exposed to labelled total genomic DNA from each species. Colonies showing differential hybridization were selected for further testing. These probes were found which allow identification of the three known species: probe pAf1 (160 bp fragment) hybridizes to DNA from An. farauti nos. 1 and 2 probe pAf2 (95 bp fragment) hybridizes to DNA from An. farauti no. 2 only and probe pAf3 (1.3 kb fragment) hybridizes strongly to DNA from An. farauti no. 3, less to no. 1 and faintly to no. 2. Increasing the stringency of hybridization reduced the cross-hybridization of probes pAf1 and pAf3. Only radioactively labelled probes were tested. Males and females and in iduals from erse habitats and localities showed the same species robe hybridization characteristics. This technique allows faster identification of the sibling species than previous methods, and has the added advantage that it allows air-dried and alcohol stored specimens to be identified.
Publisher: Springer Science and Business Media LLC
Date: 12-03-2010
DOI: 10.1007/S10096-010-0899-X
Abstract: Given the increasing aetiological importance of Streptococcus dysgalactiae subspecies equisimilis in diseases which are primarily attributed to S. pyogenes, molecular markers are essential to distinguish these species and delineate their epidemiology more precisely. Many clinical microbiology laboratories rely on agglutination reactivity and biochemical tests to distinguish them. These methods have limitations which are particularly exacerbated when isolates with mixed properties are encountered. In order to provide additional distinguishing parameters that could be used to unequivocally discriminate these two common pathogens, we assess here three molecular targets: the speB gene, intergenic region upstream of the scpG gene (IRSG) and virPCR. Of these, the former two respectively gave positive and negative results for S. pyogenes, and negative and positive results for S. dysgalactiae subsp. equisimilis. Thus, a concerted use of these nucleic acid-based methods is particularly helpful in epidemiological surveillance to accurately assess the relative contribution of these species to streptococcal infections and diseases.
Publisher: Public Library of Science (PLoS)
Date: 17-07-2012
Publisher: Springer Science and Business Media LLC
Date: 12-08-2014
Publisher: Informa UK Limited
Date: 12-2009
DOI: 10.1586/ERV.09.133
Abstract: Group A streptococcus (GAS) is a bacterial pathogen responsible for a wide array of disease pathologies in humans. GAS surface M protein plays multiple key roles in pathogenesis, and serves as a target for typing and vaccine development. In this review, we have compiled GAS epidemiological studies from several countries around the world to highlight the consequences on the theoretical efficacy of two different M protein-based vaccine strategies.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/HR14022
Abstract: David Kemp's seminal contributions to molecular parasitology of malaria and scabies have placed Australian science at the forefront of research on these important human pathogens. Immunoscreening of expression clones led to the identification of several vaccine candidates against malaria. His contributions to scabies research are pivotal to our understanding of bacteria–parasite–human interactions. Other notable achievements are: the discovery of one of the earliest known multi-gene families the first cloning of linked variable-region genes in the immunoglobulin heavy-chain locus the invention of highly cited molecular biology methods, namely Northern blotting and inverted-PCR and contributions to ‘molecular public health' by his work on various bacterial infections relevant to the health of Indigenous Australians. Kemp's manifest enthusiasm for science was highly infectious. He mentored many high-achieving scientists. In addition to his exemplary career as a scientist, he was a musician at heart and a passionate rock fossicker.
Publisher: Elsevier BV
Date: 11-1992
DOI: 10.1016/0147-619X(92)90056-G
Abstract: Transcription of the 7.5-kb cryptic plasmid of Chlamydia trachomatis serovar L2 was investigated. Faint, diffuse transcripts of about 1.6 and 2.2 kb and intense short transcripts of about 250 and 430 bases were identified by Northern blot analysis. The short transcripts were found to have a common 5' end corresponding to bp 501 relative to the unique BamHI site of the plasmid and to terminate at different downstream sites. Putative promoter sequences of TTGCCA and TATATT, which closely resemble the consensus recognition site of Escherichia coli sigma 70, were identified at the -35 and -10 positions upstream from the 5' end of the short transcripts made in chlamydia. Transcripts of similar sizes were also expressed from this promoter in E. coli harboring a recombinant plasmid encoding the short transcripts. The short transcripts encode a common open reading frame (ORF) of 34 codons however, a strong ribosome binding site was not found in the vicinity of the initiator codon, and it is not known whether the transcripts are translated in vivo. A large ORF of 330 codons, which has been shown to encode a hypothetical protein containing conserved domains of recombinase-like proteins, is antisense to the short transcripts. Transcripts encoding the large ORF could not be detected directly by Northern blot or primer extension analysis. However, transcripts were detected by polymerase chain reaction lification of the large ORF cDNA and when Southern blots of single-stranded antisense DNA for the large ORF were probed with radiolabeled RNA synthesized by host-free chlamydial reticulate bodies. Thus, both strands of the chlamydial plasmid are transcribed in the region encoding the short transcripts. We propose that the short transcripts play a regulatory role as antisense RNAs.
Publisher: American Society for Microbiology
Date: 02-2003
DOI: 10.1128/JCM.41.2.883-885.2003
Abstract: Horseradish peroxidase-like type III secretion (TTS1) genes were present in all 116 Northern Australian Burkholderia pseudomallei isolates tested but were not detected in other common environmental Burkholderia species. PCR of TTS1 genes may prove valuable as a diagnostic test.
Publisher: Elsevier BV
Date: 04-2006
Publisher: Elsevier BV
Date: 03-1982
Publisher: Elsevier BV
Date: 04-2006
Publisher: Cambridge University Press (CUP)
Date: 24-10-2008
DOI: 10.1017/S0950268807009740
Abstract: Skin infections are highly prevalent in many Australian Aboriginal communities. This study aimed to determine the prevalence of group A streptococcus (GAS) and Staphylococcus aureus in skin sores of Indigenous people living in an urban setting. We undertook a cross-sectional study of 173 children and youths attending the Wuchopperen Clinic (Cairns) for treatment of skin infections. Participants were interviewed using a structured questionnaire, and a skin lesion swab obtained. The median age was 5·3 years, with 42% identifying themselves as Torres Strait Islanders and 34% as Aboriginal. Impetigo (65%) was the most frequent diagnosis reported followed by scabies (19%) 79% of the lesions had erythema and 70% had exudate. Of 118 lesions, 114 were positive for pathogenic bacteria, with GAS isolated in 84 cases and S. aureus in 92 both these species were recovered from 63 lesions. Significant ersity of emm -types of GAS was associated with skin lesions in Indigenous patients (22 emm -types identified). Fifteen of the 92 S. aureus isolates were suggestive of being community-acquired on the basis of antimicrobial susceptibility profile and nine of these strains were co-cultured from nine lesions. These results have implications for future changes of antibiotic policies for the treatment of skin infections in this population.
Publisher: Elsevier BV
Date: 03-2007
DOI: 10.1016/J.MICINF.2006.12.006
Abstract: "Streptococcal inhibitor of complement" (SIC) and "distantly related to SIC" (DRS) are related virulence factors secreted by M1 and M12 strains of GAS, respectively. The human mucosal innate immune system, important components of which are beta-defensins, secretory leukocyte proteinase inhibitor (SLPI) and lysozyme, provides the first line of defence against microorganisms. We report the interaction between DRS and these proteins further investigations into the interaction of SIC with the beta-defensins and compare the sensitivity of M12 and M1 GAS to SLPI. We show that SLPI, which kills M1 GAS and is inhibited by SIC, cannot kill M12 GAS. DRS cannot inhibit SLPI killing of M1 GAS, although ELISA shows binding of DRS to SLPI. We suggest that the target for SLPI on M1 GAS resembles SIC, and soluble SIC inhibits by acting as a decoy for SLPI. M12 GAS may not have this target and cannot interact with SLPI. DRS inhibits the antibacterial action of hBD-2 and hBD-3. Binding of both SIC and DRS to hBD-2, and DRS to hBD-3, shows small positive enthalpy, suggesting that binding is largely hydrophobic. The data for SIC and hBD-3 indicate that this is not a homogeneous bimolecular interaction. We conclude that DRS shares several of the properties of SIC, and therefore can be considered an important virulence factor of M12 GAS and an aid to colonization of the host mucosae.
Publisher: Elsevier BV
Date: 04-2006
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.MICINF.2004.06.007
Abstract: Surface exposed fibronectin-binding proteins (FBPs) play an important role in the adherence of Streptococcus pyogenes (group A streptococcus, GAS) to host cells. This pathogen expresses numerous FBPs, of which SfbI, SfbII and PrtF2 are major surface exposed FBPs. However, GAS strains differ in the genetic potential to express these proteins. To test whether this difference reflects in differences in fibronectin (Fn) binding, a set of circulating strains previously examined for adherence to host cells was used. The 68 distinct strains were isolated from throat, skin and blood. They were analyzed for (a) the presence of genes for SfbI, SfbII and PrtF2 and (b) the extent of Fn binding. The results suggest that strains possessing two or more of the genes for these FBPs bound Fn significantly more than strains possessing none or one of the genes. No correlation between the extent of Fn binding and the tissue site of isolation was found. Furthermore, together with our previous studies on adherence capacity of these GAS strains, we found no correlation between Fn binding ability and the avidity of the strains to adhere to epithelial cells. We suggest that while Fn binding is important for adhesion, for many GAS strains the extent of Fn binding is not the critical determinant of adherence.
Publisher: Cambridge University Press (CUP)
Date: 02-1999
DOI: 10.1017/S0950268898001952
Abstract: Reports of increasing incidence and severity of invasive group A streptococcal (GAS) infections come mainly from affluent populations where exposure to GAS is relatively infrequent. We conducted a 6-year retrospective review of GAS bacteraemia in the Northern Territory of Australia, comparing the Aboriginal population (24% of the study population), who have high rates of other streptococcal infections and sequelae, to the non-Aboriginal population. Of 72 episodes, 44 (61%) were in Aboriginal patients. All 12 cases in children were Aboriginal. Risk factors were implicated in 82% of episodes (91% in adults) and there was no significant difference in the proportion of Aboriginal compared to non-Aboriginal patients with at least one risk factor. Genetic typing of isolates revealed no dominant strains and no evidence of a clone which has been a common cause of these infections elsewhere.
Publisher: Elsevier BV
Date: 06-1994
DOI: 10.1016/0378-1119(94)90198-8
Abstract: The genes (emm) encoding M proteins, from isolates of group-A streptococci (GAS) serotyped as M52, M53, M80 and M nontypeable (MNT serologically related to M53 and M80), were examined. Characterization of emm from these GAS revealed some discrepancies with serotyping, illustrating the difficulty in serotype determination when cross-reactions occur. DNA sequences corresponding to the N-terminal region of M proteins from the isolates showed considerable similarity both in the hypervariable region and the repeat regions. We propose that these serotypes form a family of closely related M types. Frameshift mutations in the hypervariable region followed by a corrective (compensatory) frameshift were observed. This may be an effective mechanism for generating antigenic ersity in the M protein.
Publisher: Elsevier BV
Date: 03-1980
Publisher: Wiley
Date: 03-2019
DOI: 10.1111/SUM.12467
Abstract: The impacts of a wildfire and subsequent rainfall event in 2013 in the Warrumbungle National Park in New South Wales, Australia were examined in a project designed to provide information on post‐fire recovery expectations and options to land managers. A coherent suite of sub‐projects was implemented, including soil mapping, and studies on soil organic carbon ( SOC ) and nitrogen (N), erosion rates, groundcover recovery and stream responses. It was found that the loss of SOC and N increased with fire severity, with the greatest losses from severely burnt sandstone ridges. Approximately 2.4 million t of SOC and ~74,000 t of N were lost from soil to a depth of 10 cm across the 56,290 ha affected. Soil loss from slopes during the subsequent rainfall event was modelled up to 25 t ha −1 , compared to a long‐term mean annual soil loss of 1.06 t ha −1 year −1 . Groundcover averages generally increased after the fire until spring 2015, by which time rates of soil loss returned to near pre‐fire levels. Streams were filled with sand to bank full levels after the fire and rainfall. Rainfall events in 2015–2016 shifted creek systems into a major erosive phase, with incision through the post‐fire sandy bedload deposits, an erosive phase likely related to loss of topsoils over much of the catchment. The effectiveness of the research was secured by a close engagement with park managers in issue identification and a communications programme. Management outcomes flowing from the research included installation of erosion control works, redesign of access and monitoring of key mass movement hazard areas.
Publisher: Wiley
Date: 03-2019
DOI: 10.1111/SUM.12502
Abstract: The New South Wales ( NSW ) Soil Knowledge Network ( SKN ) is a group of retired soil specialist volunteers, who strive to promote the importance of soils through knowledge and expertise. The Soil Knowledge Network is unique and represents a new direction in knowledge sharing using the passion of recently retired soil scientists to support new and early career soil scientists. The terms ‘legacy science’ and ‘sharing legacy knowledge’ are used here to describe SKN activities. This paper reflects on the progress of the SKN and assesses its positive impact on raising the awareness and understanding of soils using qualitative ex les from workshops, a survey of soil team coaches at the 2018 National soil judging competition, and metrics from social media and online resources. SKN successes and learning experiences are discussed along with notions of trust, credibility and the importance of people in delivering positive outcomes.
Publisher: Oxford University Press (OUP)
Date: 04-2004
Publisher: Springer Berlin Heidelberg
Date: 2013
DOI: 10.1007/82_2012_278
Abstract: Diseases caused by Streptococcus pyogenes (Group A streptococcus, GAS) range from superficial infections such as pharyngitis and impetigo to potentially fatal rheumatic heart disease and invasive disease. Studies spanning emm-typing surveillance to population genomics are providing new insights into the epidemiology, pathogenesis, and biology of this organism. Such studies have demonstrated the differences that exist in the epidemiology of streptococcal disease between developing and developed nations. In developing nations, where streptococcal disease is endemic, the ersity of GAS emm-types circulating is much greater than that found in developed nations. An association between emm-type and disease, as observed in developed countries is also lacking. Intriguingly, comparative genetic studies suggest that emm-type is not always a good predictor of the evolutionary relatedness of geographically distant isolates. A view of GAS as a highly dynamic organism, in possession of a core set of virulence genes that contribute to host niche specialization and common pathogenic processes, augmented by accessory genes that change the relative virulence of specific lineages is emerging. Our inability to definitively identify genetic factors that contribute to specific disease outcome underscores the complex nature of streptococcal diseases.
Publisher: Springer Science and Business Media LLC
Date: 2010
Publisher: Oxford University Press (OUP)
Date: 06-2007
DOI: 10.1086/516780
Abstract: In spite of the emerging importance of Streptococcus dysgalactiae subspecies equisimilis (human group C streptococci [GCS] and group G streptococci [GGS]) in human health, its molecular makeup remains largely undefined. Apart from sharing a phylogenetic relationship with the human pathogen group A streptococci (GAS), GCS/GGS and GAS colonize the same ecological niche and exhibit considerable overlap in their disease profiles. Such similarities imply that the virulence factors associated with diseases may also be similar. In this study, we used a targeted microarray containing 216 GAS virulence genes to profile the virulence gene repertoires of 58 S. dysgalactiae subspecies equisimilis isolates recovered during human infections. We performed comparative analyses to investigate the relationship between GAS virulence genes in and the invasive potential of GCS/GGS. Up to one-half of the GAS virulence genes represented in the microarray were identified in GCS/GGS. No statistical differences were observed between isolates harboring the group C versus group G carbohydrates however, clustering algorithms revealed 2 genetically distinct clusters of S. dysgalactiae subspecies equisimilis isolates. No relationship was observed between the virulence profile of GCS/GGS and the propensity for disease or the tissue site of isolation. This is, to our knowledge, the first comprehensive analysis of the virulence profile of S. dysgalactiae subspecies equisimilis, and it enables novel insights into the pathogen's genetic basis of disease propensity shared with GAS. Human group C and group G streptococci may not be considered to be separate species in fact, they may constitute 2 distinct lineages. Additional incongruent relationships were observed between virulence profiles and GCS/GGS disease propensity.
Publisher: American Society for Microbiology
Date: 05-2003
Publisher: Elsevier BV
Date: 11-1987
DOI: 10.1016/0147-619X(87)90063-1
Abstract: The 7.5-kb plasmid of Chlamydia trachomatis, trachoma biovar, was mapped for restriction enzyme sites and sequenced. The complete nucleotide sequence, the first reported for any chlamydial plasmid, revealed nine open reading frames which could code for polypeptides greater than 10 kDa. These putative polypeptides contain 35-47% hydrophobic amino acid residues. Two putative polypeptides of 30 kDa are highly basic and one of 23 kDa is acidic. A region composed of four 22-bp repeats, AT-rich clusters, an inverted repeat, and a 30-kDa basic protein is similar in organization to the origins of replication in a number of Escherichia coli plasmids. Northern blot analysis of the plasmid RNA showed transcripts longer than the length of the plasmid, suggesting a single transcription initiation signal.
Publisher: Elsevier BV
Date: 11-2007
DOI: 10.1016/J.IJMM.2007.02.007
Abstract: Group A streptococcus (GAS) is responsible for a range of human diseases that vary in their clinical manifestations and severity. While numerous virulence factors have been described, the way these factors interact to promote different streptococcal diseases is less clear. In order to identify multifactorial relationships between GAS and the human host, novel high-throughput techniques such as microarrays are necessary. We have performed comparative studies using custom-designed virulence arrays to enhance our understanding of the high degree of genotypic variation that occurs in streptococci. This study has pointed to mobile genetic elements as the major agents that promote variation. Our results show that multiple combinations of genes might bring about similar clinical pictures. This adds further complexity to the intricate relationship between pathogen and host.
Publisher: Medknow
Date: 2010
Publisher: Springer Science and Business Media LLC
Date: 06-1997
Abstract: Polymerase chain reaction (PCR) ribotyping of many bacterial species has shown that polymorphism of the ribosomal RNA (rRNA) operons, within and between strains, is common. Restriction fragment length polymorphism (RFLP) analysis of the rRNA operons of thirty-two genetically and geographically distinct strains of group A streptococci (GAS) revealed that there are only two major HaeIII PCR-ribotypes. This variation is due to a single nucleotide change within the 16S-23S intergenic spacer regions of these operons. As in many other bacterial species, this spacer region in streptococci also contains the gene for tRNA(ala). Within each GAS isolate, hybridization results are consistent with the presence of six rRNA operons. Interestingly, for a given strain, irrespective of its origin, all six rRNA operons have the same RFLP pattern. This contrasts with the findings in many other bacteria species, where heterogeneity of the rRNA operons within a genome is a common feature. This lack of heterogeneity of rRNA operons in an organism that is known to acquire genetic sequences through horizontal transfer is intriguing.
Publisher: Springer Science and Business Media LLC
Date: 1976
DOI: 10.1007/BF00331556
Publisher: Elsevier BV
Date: 05-2005
Publisher: Springer Science and Business Media LLC
Date: 09-1981
DOI: 10.1007/BF00376789
Publisher: Springer Science and Business Media LLC
Date: 02-1984
DOI: 10.1007/BF00420229
Publisher: American Society for Microbiology
Date: 12-2003
DOI: 10.1128/IAI.71.12.6701-6706.2003
Abstract: All isolates of serotype M1 of group A streptococci possess a gene for streptococcal inhibitor of complement (SIC) in the mga regulon, which harbors genes for other virulence factors, such as M and M-like proteins, C5a peptidase, and a regulator. In serotype M57 the gene for a protein that is closely related to SIC ( crs57 ) is located outside the mga regulon. We mapped the location of the crs57 gene in six strains of emm57 (gene encoding the M57 protein) sequence types to an intergenic region between the ABC transporter gene (SPy0778) and the gene for a small ribosomal protein ( rpsU ). The noncoding sequences on both sides of crs57 exhibited high degrees of identity to the corresponding regions of sic from M1 strains. This included one of the inverted repeat sequences of IS 1562 but not the insertion element itself. These observations suggest that crs57 was recently acquired by serotype M57 or its progenitor via horizontal acquisition from serotype M1. The six emm57 sequence type isolates analyzed in this study belong to two distinct molecular types (vir types VT8 and VT101). Although the crs57 sequences from VT8 strains had very few substitution mutations, the VT101 crs57 sequence had a large number of such mutations. The CRS57 proteins from these strains are secretory products and have the ability to bind to complement proteins. All these proteins contain several tryptophan-rich repeats designated DWS motifs and internal repeat sequences. In all of these structural and biochemical characteristics CRS57 resembles SIC from M1 strains. Hence, CRS57 has a functional role similar to that of SIC in an M1 strain.
Publisher: Oxford University Press (OUP)
Date: 15-02-2004
DOI: 10.1086/381452
Publisher: Elsevier BV
Date: 04-2006
Publisher: Oxford University Press (OUP)
Date: 03-1992
DOI: 10.1016/0035-9203(92)90577-Y
Abstract: We have sequenced recombinant plasmid probes for each of 3 Anopheles farauti complex species and identified internal oligonucleotides of 25-26 base pairs, specific for each member of the complex. Synthetic oligonucleotides oAf1, oAf2 and oAf3, when radiolabelled and hybridized with deoxyribonucleic acid from An. farauti, reacted as highly specific probes for An. farauti numbers 1, 2 and 3 respectively. These probes are effective on air-dried or alcohol-preserved larval, pupal or adult specimens.
Publisher: Springer Science and Business Media LLC
Date: 21-12-2014
DOI: 10.1007/S10792-013-9891-7
Abstract: Various retinal manifestations can occur following a febrile illness due to viral, bacterial or protozoal etiology. As there are limited data in the literature, we undertook this study to analyse the clinical presentation of post-fever retinitis due to various etiologies, as well as its course and management. This was a retrospective study of 14 consecutive cases who presented to the Vitreo Retina Department of our hospital over a 1-year period between January 2010 and December 2010. All patients underwent detailed ophthalmic examination and relevant investigations including fundus fluorescein angiography and optical coherence tomography (OCT). Basic and specific investigations were performed as necessary. All patients were given systemic steroids which were tapered based on clinical response. Twenty-one eyes of 14 patients (7 bilateral, 7 unilateral) were studied. Onset of ocular symptoms was approximately 3 weeks after fever. Four patients had specific etiology-one each of chikungunya, enteric fever, malaria and abdominal abscess with pneumococcal pneumonia. The presenting visual acuity of the affected eyes averaged 2/60. Six eyes had relative afferent pupillary defect. All patients had solitary or multiple patches of retinitis at the posterior pole and exudation at the macula. OCT through the lesions revealed inner retinal hyperreflectivity and thickening with after-shadowing. All patients showed improvement in vision with unilateral cases improving to an average of 6/12 and bilateral cases improving to an average of 6/24. Patients also showed resolution of retinitis, macular edema and serous detachment. Post-fever retinitis as a condition manifested approximately 3 weeks after onset of fever. Irrespective of the cause of the fever, clinical presentation of cases was similar with inner retinitis at the posterior pole and a favourable response to steroids, suggesting a possible immunological basis for this condition.
Publisher: Oxford University Press (OUP)
Date: 10-2006
DOI: 10.1086/507537
Abstract: The factors behind the reemergence of severe, invasive group A streptococcal (GAS) diseases are unclear, but it could be caused by altered genetic endowment in these organisms. However, data from previous studies assessing the association between single genetic factors and invasive disease are often conflicting, suggesting that other, as-yet unidentified factors are necessary for the development of this class of disease. In this study, we used a targeted GAS virulence microarray containing 226 GAS genes to determine the virulence gene repertoires of 68 GAS isolates (42 associated with invasive disease and 28 associated with noninvasive disease) collected in a defined geographic location during a contiguous time period. We then employed 3 advanced machine learning methods (genetic algorithm neural network, support vector machines, and classification trees) to identify genes with an increased association with invasive disease. Virulence gene profiles of in idual GAS isolates varied extensively among these geographically and temporally related strains. Using genetic algorithm neural network analysis, we identified 3 genes with a marginal overrepresentation in invasive disease isolates. Significantly, 2 of these genes, ssa and mf4, encoded superantigens but were only present in a restricted set of GAS M-types. The third gene, spa, was found in variable distributions in all M-types in the study. Our comprehensive analysis of GAS virulence profiles provides strong evidence for the incongruent relationships among any of the 226 genes represented on the array and the overall propensity of GAS to cause invasive disease, underscoring the pathogenic complexity of these diseases, as well as the importance of multiple bacteria and/or host factors.
Publisher: Elsevier BV
Date: 07-2005
DOI: 10.1016/J.MICINF.2005.03.018
Abstract: Streptococcus dysgalactiae subsp. equisimilis (human group G streptococcus, GGS) is generally regarded as a commensal organism but can cause a spectrum of human diseases very similar to that caused by S. pyogenes (group A streptococcus, GAS). Lateral acquisition of genes between these two phylogenetically closely related species is well documented. However, the extent and mechanisms of lateral acquisitions is not known. We report here genomic subtraction between a pathogenic GGS isolate and a community GGS isolate and analyses of the gene sequences unique to the pathovar. Our results show that cross-species genetic transfers are common between GGS and two closely related human pathogens, GAS and the group B streptococcus. We also demonstrate that mobile genetic elements, such as phages and transposons, play an important role in the ongoing inter-species transfers of genetic traits between extant organisms in the community. Furthermore, lateral gene transfers between GAS and GGS may occur more frequently in geographical regions of high GAS endemicity. These observations may have important implications in understanding the epidemiology of streptococcal diseases in such regions.
Publisher: American Society for Microbiology
Date: 07-2004
DOI: 10.1128/IAI.72.7.3981-3986.2004
Abstract: An extracellular protein of Streptococcus pyogenes , streptococcal inhibitor of complement (SIC), and its variant, called DRS (distantly related to SIC), are expressed by some S. pyogenes strains. SIC from type 1 (M1) isolates of S. pyogenes interferes with complement-mediated cell lysis, reportedly via its interaction with complement proteins. In this study we demonstrate that S. pyogenes strains carrying emm12 and emm55 (the genes for the M12 and M55 proteins, respectively) express and secrete DRS. This protein, like SIC, binds to the C6 and C7 complement proteins, and competition enzyme-linked immunosorbent assay experiments demonstrate that DRS competes with SIC for C6 and C7 binding. Similarly, SIC competes with DRS for binding to the complement proteins. Despite this, the recombinant DRS preparation showed no significant effect on complement function, as determined by lysis of sensitized sheep erythrocytes. Furthermore, the presence of DRS is not inhibitory to SIC activity.
Publisher: Elsevier BV
Date: 1999
Abstract: Streptococcus pyogenes infection and acute glomerulonephritis (AGN), a non-suppurtave disease, are endemic in the Aboriginal people of the Northern Territory (NT) of Australia. Vir typing, a locus-specific polymerase chain reaction (PCR)-based typing method [Gardiner, Hartas, Currie et al PCR Meth Appl 1995 4: 288-93], has revealed high ergence among the NT streptococcal strains. A total of 76 Vir types (VTs) representing about 95% of the NT isolates were screened for sic, a gene for streptococcal inhibitor of complement function, by PCR and hybridization. This revealed that seven VTs are positive for sic, and there are two classes of the gene: those closely related to sic (CRS) originally described by Akesson, Sjoholm & Bjorck [ J. Biol. Chem. 1996 271: 1081-8] and those distantly related to sic (DRS). Among the CRS-positive VTs, VT16, VT78 and VT91 have emm (gene for M protein) encoding type 1 M protein or related specificity, and VT8 and VT101 contain emm57 or related alleles. Chromosomal location of CRS in emm57 is different from that in emm1 or related strains. The DRS-positive VT18 and VT52 contained emm55 and emm12 respectively, which are phylogenetically related. Strains of S. pyogenes types 1, 12, 55 and 57 are known to be associated with AGN. Restricted distribution of CRS and DRS among the M types historically associated with AGN suggests that these sic alleles may have a role in AGN pathogenesis.
Publisher: American Society for Microbiology
Date: 2004
DOI: 10.1128/IAI.72.1.364-370.2004
Abstract: Reports of resurgence in invasive group A streptococcal (GAS) infections come mainly from affluent populations with infrequent exposure to GAS. In the Northern Territory (NT) of Australia, high incidence of invasive GAS disease is secondary to endemic skin infection, serotype M1 clones are rare in invasive infection, the ersity and level of exposure to GAS strains are high, and no particular strains dominate. Expression of a plasminogen-binding GAS M-like protein (PAM) has been associated with skin infection in isolates elsewhere (D. Bessen, C. M. Sotir, T. M. Readdy, and S. K. Hollingshead, J. Infect. Dis. 173: 896-900, 1996), and subversion of the host plasminogen system by GAS is thought to contribute to invasion in animal models. Here, we describe the relationship between plasminogen-binding capacity of GAS isolates, PAM genotype, and invasive capacity in 29 GAS isolates belonging to 25 distinct strains from the NT. In the presence of fibrinogen and streptokinase, invasive isolates bound more plasminogen than isolates from uncomplicated infections ( P ≤ 0.004). Only PAM-positive isolates bound substantial levels of plasminogen by a fibrinogen-streptokinase-independent pathway (direct binding). Despite considerable amino acid sequence variation within the A1 repeat region of PAM where the plasminogen-binding domain maps, the critical lysine residue was conserved.
Publisher: Wiley
Date: 10-09-2019
DOI: 10.1111/JNC.14829
Abstract: The past 20 years have resulted in unprecedented progress in understanding brain energy metabolism and its role in health and disease. In this review, which was initiated at the 14th International Society for Neurochemistry Advanced School, we address the basic concepts of brain energy metabolism and approach the question of why the brain has high energy expenditure. Our review illustrates that the vertebrate brain has a high need for energy because of the high number of neurons and the need to maintain a delicate interplay between energy metabolism, neurotransmission, and plasticity. Disturbances to the energetic balance, to mitochondria quality control or to glia-neuron metabolic interaction may lead to brain circuit malfunction or even severe disorders of the CNS. We cover neuronal energy consumption in neural transmission and basic ('housekeeping') cellular processes. Additionally, we describe the most common (glucose) and alternative sources of energy namely glutamate, lactate, ketone bodies, and medium chain fatty acids. We discuss the multifaceted role of non-neuronal cells in the transport of energy substrates from circulation (pericytes and astrocytes) and in the supply (astrocytes and microglia) and usage of different energy fuels. Finally, we address pathological consequences of disrupted energy homeostasis in the CNS.
Publisher: Cambridge University Press (CUP)
Date: 02-1999
DOI: 10.1017/S0950268898001812
Abstract: Aboriginal communities in Northern Australia with high rates of group A streptococcal (GAS) skin infection in childhood also have high rates of renal failure in adult life. In a cross-sectional study of one such high risk community, albuminuria was used as a marker of renal disease. The prevalence of albuminuria increased from 0/52 in subjects aged 10–19 years to 10/29 (32·9%) in those aged 50 or more ( P ·001). Antibodies to streptococcal M protein, markers of past GAS infection, were present in 48/52 (92%) at ages 10–19 years, 16/32 (50%) at ages 30–39, and 20/29 (69%) in those aged 50 or more. After allowing for the age-dependencies of albuminuria and of M protein antibodies ( P ·001) albuminuria was significantly associated with M protein antibodies ( P ·01). Thus, 72% of adults aged 30 or more with M protein antibodies also had albuminuria, compared with only 21% of those who were seronegative. More detailed modelling suggested that although most Aboriginal people in this community developed M protein antibodies following GAS infection in childhood, the development of proteinuria was associated with the persistence of such seropositivity into adult life. The models predicted that proteinuria developed at a mean age of 30 years in seropositive persons, at 45 years in seronegative persons who were overweight, and at 62 years in seronegative persons of normal weight. We demonstrated a clear association between evidence of childhood GAS infection and in idual risk of proteinuria in adult life. This study provided a strong rationale for prevention of renal disease through the more effective control of GAS skin infections in childhood and through the prevention of obesity in adult life.
Publisher: Springer Science and Business Media LLC
Date: 04-1980
DOI: 10.1007/BF00390946
Publisher: Elsevier BV
Date: 07-2004
Start Date: 2008
End Date: 2013
Funder: National Health and Medical Research Council
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