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Robert L. Owen

Bio: Robert L. Owen is an academic researcher from University of California, San Francisco. The author has contributed to research in topics: Microfold cell & Peyer's patch. The author has an hindex of 36, co-authored 87 publications receiving 6002 citations. Previous affiliations of Robert L. Owen include Okayama University & Veterans Health Administration.


Papers
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Journal ArticleDOI
TL;DR: The newly discovered epithelial cells contain multiple vesicles that suggest a transport function, possibly for luminal antigenic material or for secretory immunoglobulin, in human intestinal mucosal cell type M cells.

730 citations

Journal ArticleDOI
TL;DR: Transport of intestinal luminal material by M cells with subsequent uptake by lymphocytes provides a specific route for antigen uptake into the intestinal lymphoid system.

651 citations

Journal ArticleDOI
TL;DR: Progress is being made with respect to in vitro propagation of microsporidia, which is crucial for developing antimicrosporidial drugs, and molecular techniques are being developed for diagnostic purposes, taxonomic classification, and analysis of phylogenetic relationships.
Abstract: Microsporidia are obligate intracellular spore-forming protozoal parasites belonging to the phylum Microspora. Their host range is extensive, including most invertebrates and all classes of vertebrates. More than 100 microsporidial genera and almost 1,000 species have now been identified. Five genera (Enterocytozoon spp., Encephalitozoon spp., Septata spp., Pleistophora sp., and Nosema spp.) and unclassified microsporidia (referred to by the collective term Microsporidium) have been associated with human disease, which appears to manifest primarily in immunocompromised persons. The clinical manifestations of microsporidiosis are diverse and include intestinal, pulmonary, ocular, muscular, and renal disease. Among persons not infected with human immunodeficiency virus, ten cases of microsporidiosis have been documented. In human immunodeficiency virus-infected patients, on the other hand, over 400 cases of microsporidiosis have been identified, the majority attributed to Enterocytozoon bieneusi, an important cause of chronic diarrhea and wasting. Diagnosis of microsporidiosis currently depends on morphological demonstration of the organisms themselves. Initial detection of microsporidia by light microscopic examination of tissue sections and of more readily obtainable specimens such as stool, duodenal aspirates, urine, sputum, nasal discharge, bronchoalveolar lavage fluid, and conjunctival smears is now becoming routine practice. Definitive species identification is made by using the specific fluorescein-tagged antibody (immunofluorescence) technique or electron microscopy. Treatment options are limited, but symptomatic improvement of Enterocytozoon bieneusi infection may be achieved with the anthelmintic-antiprotozoal drug albendazole. Preliminary observations suggest that Septata intestinalis and Encephalitozoon infections may be cured with albendazole. Progress is being made with respect to in vitro propagation of microsporidia, which is crucial for developing antimicrosporidial drugs. Furthermore, molecular techniques are being developed for diagnostic purposes, taxonomic classification, and analysis of phylogenetic relationships of microsporidia.

579 citations

Journal ArticleDOI
TL;DR: This new diagnostic technique serves as a practical, noninvasive means to detect microsporidia spores in stool specimens and is also applicable to the examination of duodenal aspirates.
Abstract: Background. The diagnosis of infection with Enterocytozoon bieneusi, a microsporidian organism that causes chronic diarrhea in patients infected with the human immunodeficiency virus (HIV), has depended on invasive procedures. We have developed a new method to detect microsporidia spores in feces and duodenal aspirates. Methods. Stool was obtained from four HIV-infected patients with biopsy-confirmed intestinal microsporidiosis. Slides prepared from unconcentrated, formalin-fixed stool specimens were stained with a new chromotrope-based technique and examined by light microscopy. Methods of stool concentration were also compared. The technique was then evaluated by examining 215 specimens from 134 HIV-infected persons with or without diarrhea. In addition, duodenal aspirates from 10 patients with unexplained chronic diarrhea were examined by light microscopy after staining according to the new and the traditional techniques. Results. E. bieneusi spores were found in all unconcentrated stool speci...

471 citations

Journal ArticleDOI
TL;DR: M cells convey viable enteric microbes, including V. cholerae that are not otherwise invasive, into intestinal lymphoid tissue, where mucosal immune responses are initiated andptake and transport by M cells may also assist certain pathogenic bacteria in traversing the mucosal barrier and initiating systemic infection.
Abstract: Viable Vibrio cholerae O1 were inoculated into the intestinal lumen of nonimmune rabbits. The vibrios were phagocytosed by M cells over Peyer's patch lymphoid follicles, carried in vesicles through the epithelium, and discharged among underlying lymphocytes and macrophages. Autoradiography of V. cholerae labeled with [2-3H]adenine confirmed transport. Indigenous bacteria with and without capsules were also taken up from control loops and carried through M cells into Peyer's patches. V. cholerae killed by acidification, formalin, heat, or UV irradiation were not taken up, a result that may have relevance for development of oral vaccines. Ruthenium red stain revealed gaps in the layer of mucus over M cells, glycocalyx bridging the space between vibrios and M cell microvilli, and knobby projections over membranes of M cell microvilli; these projections were not found over absorptive cells. M cells thus convey viable enteric microbes, including V. cholerae that are not otherwise invasive, into intestinal lymphoid tissue, where mucosal immune responses are initiated. Uptake and transport by M cells may also assist certain pathogenic bacteria in traversing the mucosal barrier and initiating systemic infection.

363 citations


Cited by
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Journal ArticleDOI
16 Mar 2012-Cell
TL;DR: It is suggested that a holistic approach to studying the microbiota that goes beyond characterization of community composition and encompasses dynamic interactions between all components of the microbiota and host tissue over time will be crucial for building predictive models for diagnosis and treatment of diseases linked to imbalances in the microbiota.

2,832 citations

DatasetDOI
TL;DR: The most recent version of the guidelines for the prevention and treatment of opportunistic infections (OI) in HIV-infected adults and adolescents was published in 2002 and 2004, respectively as mentioned in this paper.
Abstract: This report updates and combines earlier versions of guidelines for the prevention and treatment of opportunistic infections (OIs) in HIV-infected adults (i.e., persons aged >/=18 years) and adolescents (i.e., persons aged 13--17 years), last published in 2002 and 2004, respectively. It has been prepared by the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the HIV Medicine Association (HIVMA) of the Infectious Diseases Society of America (IDSA). The guidelines are intended for use by clinicians and other health-care providers, HIV-infected patients, and policy makers in the United States. These guidelines address several OIs that occur in the United States and five OIs that might be acquired during international travel. Topic areas covered for each OI include epidemiology, clinical manifestations, diagnosis, prevention of exposure; prevention of disease by chemoprophylaxis and vaccination; discontinuation of primary prophylaxis after immune reconstitution; treatment of disease; monitoring for adverse effects during treatment; management of treatment failure; prevention of disease recurrence; discontinuation of secondary prophylaxis after immune reconstitution; and special considerations during pregnancy. These guidelines were developed by a panel of specialists from the United States government and academic institutions. For each OI, a small group of specialists with content-matter expertise reviewed the literature for new information since the guidelines were last published; they then proposed revised recommendations at a meeting held at NIH in June 2007. After these presentations and discussion, the revised guidelines were further reviewed by the co-editors; by the Office of AIDS Research, NIH; by specialists at CDC; and by HIVMA of IDSA before final approval and publication. The recommendations are rated by a letter that indicates the strength of the recommendation and a Roman numeral that indicates the quality of evidence supporting the recommendation, so that readers can ascertain how best to apply the recommendations in their practice environments. Major changes in the guidelines include 1) greater emphasis on the importance of antiretroviral therapy for the prevention and treatment of OIs, especially those OIs for which no specific therapy exists; 2) information regarding the diagnosis and management of immune reconstitution inflammatory syndromes; 3) information regarding the use of interferon-gamma release assays for the diagnosis of latent Mycobacterium tuberculosis (TB) infection; 4) updated information concerning drug interactions that affect the use of rifamycin drugs for prevention and treatment of TB; 5) the addition of a section on hepatitis B virus infection; and 6) the addition of malaria to the list of OIs that might be acquired during international travel. This report includes eleven tables pertinent to the prevention and treatment of OIs, a figure that pertains to the diagnois of tuberculosis, a figure that describes immunization recommendations, and an appendix that summarizes recommendations for prevention of exposure to opportunistic pathogens.

1,534 citations

Journal ArticleDOI
TL;DR: There is potential for microplastics to impact human health, and assessing current exposure levels and burdens is key to guide future research into the potential mechanisms of toxicity and hence therein possible health effects.
Abstract: Microplastics are a pollutant of environmental concern Their presence in food destined for human consumption and in air samples has been reported Thus, microplastic exposure via diet or inhalation could occur, the human health effects of which are unknown The current review article draws upon cross-disciplinary scientific literature to discuss and evaluate the potential human health impacts of microplastics and outlines urgent areas for future research Key literature up to September 2016 relating to accumulation, particle toxicity, and chemical and microbial contaminants was critically examined Although microplastics and human health is an emerging field, complementary existing fields indicate potential particle, chemical and microbial hazards If inhaled or ingested, microplastics may accumulate and exert localized particle toxicity by inducing or enhancing an immune response Chemical toxicity could occur due to the localized leaching of component monomers, endogenous additives, and adsorbed enviro

1,515 citations

Journal ArticleDOI
TL;DR: This chapter provides an up to date review of the biology, biochemistry and host parasite relationships of Cryptosporidium.

1,361 citations

Journal ArticleDOI
TL;DR: The protective barrier properties of mucus secretions, how mucus affects the fate of orally administered nanoparticles, and recent developments in nanoparticles engineered to penetrate the mucus barrier are addressed.

1,205 citations