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Marja-Liisa Väisänen

Bio: Marja-Liisa Väisänen is an academic researcher from Veterans Health Administration. The author has contributed to research in topics: Porphyromonas & Anaerobic bacteria. The author has an hindex of 18, co-authored 24 publications receiving 1473 citations. Previous affiliations of Marja-Liisa Väisänen include West Los Angeles College & University of California, Los Angeles.

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TL;DR: It is speculated that, in a subgroup of children, disruption of indigenous gut flora might promote colonization by one or more neurotoxin-producing bacteria, contributing, at least in part, to their autistic symptomatology.
Abstract: In most cases symptoms of autism begin in early infancy. However, a subset of children appears to develop normally until a clear deterioration is observed. Many parents of children with "regressive"-onset autism have noted antecedent antibiotic exposure followed by chronic diarrhea. We speculated that, in a subgroup of children, disruption of indigenous gut flora might promote colonization by one or more neurotoxin-producing bacteria, contributing, at least in part, to their autistic symptomatology. To help test this hypothesis, 11 children with regressive-onset autism were recruited for an intervention trial using a minimally absorbed oral antibiotic. Entry criteria included antecedent broad-spectrum antimicrobial exposure followed by chronic persistent diarrhea, deterioration of previously acquired skills, and then autistic features. Short-term improvement was noted using multiple pre- and post-therapy evaluations. These included coded, paired videotapes scored by a clinical psychologist blinded to treatment status; these noted improvement in 8 of 10 children studied. Unfortunately, these gains had largely waned at follow-up. Although the protocol used is not suggested as useful therapy, these results indicate that a possible gut flora-brain connection warrants further investigation, as it might lead to greater pathophysiologic insight and meaningful prevention or treatment in a subset of children with autism.

555 citations

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TL;DR: The bacteriology of cutaneous or subcutaneous abscesses among intravenous drug users (IVDUs) was compared with the bacteriology in patients with no history of intravenous drugs use (non-IVDU), which yielded 173 aerobes and 131 anaerobes.
Abstract: The bacteriology of cutaneous or subcutaneous abscesses (86 specimens) among intravenous drug users (IVDUs) was compared with the bacteriology of abscesses (74 specimens) in patients with no history of intravenous drug use (non-IVDUs). The IVDU abscesses yielded 173 aerobes and 131 anaerobes. Staphylococcus aureus was the most common aerobe isolated (50% of specimens yielded this isolate), followed by "Streptococcus milleri" (46%). The commonly encountered anaerobes were Fusobacterium nucleatum (17%), pigmented Prevotella species (22%), Peptostreptococcus micros (17%), Actinomyces odontolyticus (15%), and Veillonella species (13%). The non-IVDU isolates included 116 aerobes and 106 anaerobes. S. aureus was isolated from 53% of these specimens, followed by coagulase-negative staphylococci (19%), "S. milleri" (19%), and Streptococcus pyogenes (16%). The main groups of anaerobes were Peptostreptococcus species (35%), Bacteroides species (19%), and gram-positive bacilli (31%). Overall, 67% of the IVDU isolates were of oral origin, compared with 25% of the non-IVDU isolates. Of the specimens from IVDUs and non-IVDUs, 48% and 67%, respectively, yielded only aerobes, and 2% and 4%, respectively, yielded only anaerobes. Sixty-four percent of the patients had one or more beta-lactamase-producing organisms.

157 citations

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TL;DR: Opt-80 showed good activity against most clostridia, staphylococci, and enterococci but streptococci , aerobic and facultative gram-negative rods, anaerobic gram- negative rods, and Clostridium ramosum were resistant.
Abstract: The activities of OPT-80 against 453 intestinal bacteria were compared with those of seven other drugs. OPT-80 showed good activity against most clostridia, staphylococci, and enterococci, but streptococci, aerobic and facultative gram-negative rods, anaerobic gram-negative rods, and Clostridium ramosum were resistant. Poor activity against anaerobic gram-negative rods may maintain colonization resistance.

125 citations

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TL;DR: Phenorypic and phylogenetic studies were performed on four isolates of an unidentified gram-negative, microaerotolerant, non-spore-forming, rod-shaped bacterium isolated from the feces of children, and it was proposed that the unknown fecal bacterium be classified in the genus Cetobacterium.

121 citations

Journal ArticleDOI
TL;DR: It is proposed that the unknown bacterium should be classified in a novel genus as Anaerotruncus colihominis gen. nov., sp.nov, based on phylogenetic and phenotypic evidence.
Abstract: Phenotypic and phylogenetic studies were performed on two isolates of an unidentified Gram-positive, anaerobic, non-spore-forming, rod-shaped bacterium that was isolated from human faeces. The organisms were catalase-negative, produced acetic and butyric acids as end products of metabolism and possessed a DNA G+C content of approximately 54 mol%. Comparative 16S rRNA gene sequencing demonstrated that the two isolates were related closely to each other and formed a hitherto unknown sublineage within the Clostridium leptum rRNA cluster of organisms. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium should be classified in a novel genus as Anaerotruncus colihominis gen. nov., sp. nov. The type strain of Anaerotruncus colihominis is WAL 14565T=CCUG 45055T=CIP 107754T.

85 citations


Cited by
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Journal ArticleDOI
TL;DR: The purpose of the present investigation was to attempt to define communities using data from large numbers of plaque samples and different clustering and ordination techniques, which related strikingly to clinical measures of periodontal disease particularly pocket depth and bleeding on probing.
Abstract: It has been recognized for some time that bacterial species exist in complexes in subgingival plaque. The purpose of the present investigation was to attempt to define such communities using data from large numbers of plaque samples and different clustering and ordination techniques. Subgingival plaque samples were taken from the mesial aspect of each tooth in 185 subjects (mean age 51 +/- 16 years) with (n = 160) or without (n = 25) periodontitis. The presence and levels of 40 subgingival taxa were determined in 13,261 plaque samples using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Clinical assessments were made at 6 sites per tooth at each visit. Similarities between pairs of species were computed using phi coefficients and species clustered using an averaged unweighted linkage sort. Community ordination was performed using principal components analysis and correspondence analysis. 5 major complexes were consistently observed using any of the analytical methods. One complex consisted of the tightly related group: Bacteroides forsythus, Porphyromonas gingivalis and Treponema denticola. The 2nd complex consisted of a tightly related core group including members of the Fusobacterium nucleatum/periodonticum subspecies, Prevotella intermedia, Prevotella nigrescens and Peptostreptococcus micros. Species associated with this group included: Eubacterium nodatum, Campylobacter rectus, Campylobacter showae, Streptococcus constellatus and Campylobacter gracilis. The 3rd complex consisted of Streptococcus sanguis, S. oralis, S. mitis, S. gordonii and S. intermedius. The 4th complex was comprised of 3 Capnocytophaga species, Campylobacter concisus, Eikenella corrodens and Actinobacillus actinomycetemcomitans serotype a. The 5th complex consisted of Veillonella parvula and Actinomyces odontolyticus. A. actinomycetemcomitans serotype b, Selenomonas noxia and Actinomyces naeslundii genospecies 2 (A. viscosus) were outliers with little relation to each other and the 5 major complexes. The 1st complex related strikingly to clinical measures of periodontal disease particularly pocket depth and bleeding on probing.

4,143 citations

Journal ArticleDOI
TL;DR: The advances in modeling and analysis of gut microbiota will further the authors' knowledge of their role in health and disease, allowing customization of existing and future therapeutic and prophylactic modalities.
Abstract: Gut microbiota is an assortment of microorganisms inhabiting the length and width of the mammalian gastrointestinal tract. The composition of this microbial community is host specific, evolving throughout an individual's lifetime and susceptible to both exogenous and endogenous modifications. Recent renewed interest in the structure and function of this "organ" has illuminated its central position in health and disease. The microbiota is intimately involved in numerous aspects of normal host physiology, from nutritional status to behavior and stress response. Additionally, they can be a central or a contributing cause of many diseases, affecting both near and far organ systems. The overall balance in the composition of the gut microbial community, as well as the presence or absence of key species capable of effecting specific responses, is important in ensuring homeostasis or lack thereof at the intestinal mucosa and beyond. The mechanisms through which microbiota exerts its beneficial or detrimental influences remain largely undefined, but include elaboration of signaling molecules and recognition of bacterial epitopes by both intestinal epithelial and mucosal immune cells. The advances in modeling and analysis of gut microbiota will further our knowledge of their role in health and disease, allowing customization of existing and future therapeutic and prophylactic modalities.

3,077 citations

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TL;DR: The emerging concept of a microbiota–gut–brain axis suggests that modulation of the gut microbiota may be a tractable strategy for developing novel therapeutics for complex CNS disorders.
Abstract: Recent years have witnessed the rise of the gut microbiota as a major topic of research interest in biology. Studies are revealing how variations and changes in the composition of the gut microbiota influence normal physiology and contribute to diseases ranging from inflammation to obesity. Accumulating data now indicate that the gut microbiota also communicates with the CNS — possibly through neural, endocrine and immune pathways — and thereby influences brain function and behaviour. Studies in germ-free animals and in animals exposed to pathogenic bacterial infections, probiotic bacteria or antibiotic drugs suggest a role for the gut microbiota in the regulation of anxiety, mood, cognition and pain. Thus, the emerging concept of a microbiota-gut-brain axis suggests that modulation of the gut microbiota may be a tractable strategy for developing novel therapeutics for complex CNS disorders.

3,058 citations

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TL;DR: 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.
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 ...

1,775 citations

Journal ArticleDOI
TL;DR: A detailed analysis of wound microbiology, together with current opinion and controversies regarding wound assessment and treatment, has attempted to capture and address microbiological aspects that are critical to the successful management of microorganisms in wounds.
Abstract: The majority of dermal wounds are colonized with aerobic and anaerobic microorganisms that originate predominantly from mucosal surfaces such as those of the oral cavity and gut. The role and significance of microorganisms in wound healing has been debated for many years. While some experts consider the microbial density to be critical in predicting wound healing and infection, others consider the types of microorganisms to be of greater importance. However, these and other factors such as microbial synergy, the host immune response, and the quality of tissue must be considered collectively in assessing the probability of infection. Debate also exists regarding the value of wound sampling, the types of wounds that should be sampled, and the sampling technique required to generate the most meaningful data. In the laboratory, consideration must be given to the relevance of culturing polymicrobial specimens, the value in identifying one or more microorganisms, and the microorganisms that should be assayed for antibiotic susceptibility. Although appropriate systemic antibiotics are essential for the treatment of deteriorating, clinically infected wounds, debate exists regarding the relevance and use of antibiotics (systemic or topical) and antiseptics (topical) in the treatment of nonhealing wounds that have no clinical signs of infection. In providing a detailed analysis of wound microbiology, together with current opinion and controversies regarding wound assessment and treatment, this review has attempted to capture and address microbiological aspects that are critical to the successful management of microorganisms in wounds.

1,748 citations