Pneumocystis The Organism

Pneumocystis is a eukaryotic extracellular lung pathogen that has been detected in almost every mammalian species evaluated for its presence.

Pneumocystis was long considered as a protozoan based on morphological features and its resistance to classical antifungal agents. However, in the late 1980s, Pneumocystis was included in the fungal kingdom based on phylogenetic analysis of ribosomal RNA (rRNA) sequences and observations of genome size. This position was substantiated by functional and phylogenetic comparisons of several other genes.[1]

Pneumocystis organisms were first identified and named Pneumocystis carinii in the beginning of the last century. Studies including chromosomal karyotyping, nucleotide sequence analysis, antigenic characterization, and experimental transmission of infection have shown that Pneumocystis has considerable genetic diversity and host specificity. Thus an interim trinomial name change was adopted to reflect the diversity (e.g., P. carinii f. sp. hominis for Pneumocystis infecting humans). Finally, in recognition of the special forms' genetic and functional distinctness as separate species, human Pneumocystis was renamed P. jiroveci.[2]

In the lungs, two major forms of the organism can be identified by light microscopy: the cystic form (cysts) and the trophic form (trophozoites). The cystic form (sporangium) is thick-walled, oval, approximately 5-8 mm in diameter, and contains up to eight intracystic bodies (endospores), which will become trophic forms after excystation. The trophic form (yeast) is small (2-5 mm), thin-walled, pleomorphic, and often has an eccentric nucleus. The trophozoites are often seen in clusters. Not much is known about the lifecycle, and the mode of replication has not been definitely established, but both asexual and sexual life cycles have been proposed.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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