IVOA Recommendation: The UCD1+ controlled vocabulary Version 1.23

This document describes the list of controlled terms used to build the Unified Content Descriptors, Version 1+ (UCD1+). The document describing the UCD1+ can be found at the URL: http://www.ivoa.net/Documents/latest/UCD.html. This document reviews the structure of the UCD1+ and presents the current vocabulary

The Pneumocystis life cycle

First recognised as "schizonts" of Trypanosoma cruzi , Pneumocystis organisms are now considered as part of an early-diverging lineage of Ascomycetes. As no robust long-term culture model is available, most data on the Pneumocystis cell cycle have stemmed from ultrastructural images of infected mammalian lungs. Although most fungi developing in animals do not complete a sexual cycle in vivo, Pneumocystis species constitute one of a few exceptions. Recently, the molecular identification of several key players in the fungal mating pathway has provided further evidence for the existence of conjugation and meiosis in Pneumocystis organisms. Dynamic follow-up of stage-to-stage transition as well as studies of stage-specific proteins and/or genes would provide a better understanding of the still hypothetical Pneumocystis life cycle. Although difficult to achieve, stage purification seems a reasonable way forward in the absence of efficient culture systems. This mini-review provides a comprehensive overview of the historical milestones leading to the current knowledge available on the Pneumocystis life cycle

SYTO-13, a Viability Marker as a New Tool to Monitor In Vitro Pharmacodynamic Parameters of Anti-Pneumocystis Drugs.

While Pneumocystis pneumonia (PcP) still impacts the AIDS patients, it has a growing importance in immunosuppressed HIV-negative patients. To determine the anti-Pneumocystis therapeutic efficacy of new compounds, animal and in vitro models have been developed. Indeed, well-designed mouse or rat experimental models of pneumocystosis can be used to describe the in vivo anti-Pneumocystis activity of new drugs. In vitro models, which enable the screening of a large panel of new molecules, have been developed using axenic cultures or co-culture with feeder cells; but no universally accepted standard method is currently available to evaluate anti-Pneumocystis molecules in vitro. Thus, we chose to explore the use of the SYTO-13 dye, as a new indicator of Pneumocystis viability. In the present work, we established the experimental conditions to define the in vitro pharmacodynamic parameters (EC50, Emax) of marketed compounds (trimethoprim/sulfamethoxazole, pentamidine, atovaquone) in order to specifically measure the intrinsic activity of these anti-P. carinii molecules using the SYTO-13 dye for the first time. Co-labelling the fungal organisms with anti-P. carinii specific antibodies enabled the measurement of viability of Pneumocystis organisms while excluding host debris from the analysis. Moreover, contrary to microscopic observation, large numbers of fungal cells can be analyzed by flow cytometry, thus increasing statistical significance and avoiding misreading during fastidious quantitation of stained organisms. In conclusion, the SYTO-13 dye allowed us to show a reproducible dose/effect relationship for the tested anti-Pneumocystis drugs

Growth and airborne transmission of cell-sorted life cycle stages of Pneumocystis carinii.

Pneumocystis organisms are airborne opportunistic pathogens that cannot be continuously grown in culture. Consequently, the follow-up of Pneumocystis stage-to-stage differentiation, the sequence of their multiplication processes as well as formal identification of the transmitted form have remained elusive. The successful high-speed cell sorting of trophic and cystic forms is paving the way for the elucidation of the complex Pneumocystis life cycle. The growth of each sorted Pneumocystis stage population was followed up independently both in nude rats and in vitro. In addition, by setting up a novel nude rat model, we attempted to delineate which cystic and/or trophic forms can be naturally aerially transmitted from host to host. The results showed that in axenic culture, cystic forms can differentiate into trophic forms, whereas trophic forms are unable to evolve into cystic forms. In contrast, nude rats inoculated with pure trophic forms are able to produce cystic forms and vice versa. Transmission experiments indicated that 12 h of contact between seeder and recipient nude rats was sufficient for cystic forms to be aerially transmitted. In conclusion, trophic- to cystic-form transition is a key step in the proliferation of Pneumocystis microfungi because the cystic forms (but not the trophic forms) can be transmitted by aerial route from host to host

Relationships between drug concentrations and <i>P</i>. <i>carinii</i> viability inhibition of pentamidine, atovaquone and trimethoprim-sulfamethoxazole (TMP/SMX).

<p>Values of <i>P</i>. <i>carinii</i> viability inhibition are calculated from the SYTO-13 live-cell staining assay. To calculate the percentage of viability inhibition in relation with drug concentrations, one drug-free control was included in each assay. All susceptibility assays were set up in triplicate.</p

SYTO-13 labelling of <i>P</i>. <i>carinii</i> trophic and cystic forms.

<p>All <i>P</i>. <i>carinii</i> life cycle stages were stained in red (panels A–D) with a home-made anti-<i>Pneumocystis</i> polyclonal antibody, recognized by an Alexa-647-conjugated secondary antibody. SYTO-13 nuclear staining of viable <i>P</i>. <i>carinii</i> is displayed for corresponding fields (panels E–H). Differential Interference Contrast (DIC) pictures of corresponding fields are also shown (I–L). Panels (B, F, J) and (D, H, L), show an isolated cystic form with one or several labelled nuclei. In the other panels, cystic forms (arrowheads) and trophic forms are well visible. The white arrows show non-viable <i>Pneumocystis</i> organisms stained in red but did not display any nuclear green fluorescence (Panels C, G, K). Bar = 5 μm.</p

Viability assessment of <i>P</i>. <i>carinii</i> using SYTO-13 by flow cytometry analysis.

<p>The data are displayed as histograms displaying 10,000 <i>P</i>. <i>carinii</i> collected events. The axes represent the relative number of cells (y axis) and the cell-associated fluorescence intensity on a logarithmic scale (x axis). Panel A shows the gated (R1) <i>P</i>. <i>carinii</i> population labelled with a rat specific polyclonal antibody and a goat anti-rat IgG antibody conjugated to Alexa-647 (FL4 channel). The intensity of SYTO-13 live-cell nucleic acid staining is analyzed within the gated <i>P</i>. <i>carinii</i> population (FL1 channel) for <i>P</i>. <i>carinii</i> organisms cultured during 4 days without (panel B), with 0.15 μM (panel C) or 90 μM (panel D) of pentamidine. The gated population R2 represents the viable <i>Pneumocystis</i> cells. The percentages of viability are indicated for each histogram. The presented histograms are representative of one experiment.</p

<i>In vitro</i> pharmacodynamic parameters of pentamidine, atovaquone and trimethoprim-sulfamethoxazole (TMP/SMX) calculated using the SYTO-13 assay.

<p><i>In vitro</i> pharmacodynamic parameters of pentamidine, atovaquone and trimethoprim-sulfamethoxazole (TMP/SMX) calculated using the SYTO-13 assay.</p