Biology Of The Organisms

Chlamydiae are obligate intracellular bacteria of limited metabolic capability, characterized by a dimorphic growth cycle. The infectious form is called the elementary body (EB) and is a condensed sporelike spheroid. The EB is metabolically inactive, consisting of a tightly compacted chromosome or nucleoid, and an outer membrane of covalently linked lipopolysaccharides. When it encounters host cells, the EB is taken in by receptor-mediated endocytosis. It has been suggested that a trimolecular mechanism is used to bridge a host receptor with a chlamydial receptor by glycosaminoglycan.[1] The man-nose receptor has also been suggested to have a role in the EB's entry into the cell.[2] The engulfed EB is enclosed in an endosome which does not fuse with a lysosome.

Several hours after entering the cell, the EB converts to a metabolically active form called the reticulate body (RB) that undergoes binary fission, forming microscopically visible inclusions containing hundreds of organisms within 24 hr. In a further 24-48 hr, the reticulate bodies condense to transform into infectious EBs that are liberated as a result of cell lysis. Polysaccharide components may form within the inclusions after 48 to 60 hr of development, depending on the chlamydial species. Chlamydia trachomatis can be distinguished from C. psittaci and C. pneumoniae as a result of this poly-saccharide material, which stains brown with iodine. Chlamydia psittaci and C. pecorum essentially cause infections of animals, with humans becoming infected as a result of exposure to infected secretions of those animals.

In contrast, C. pneumoniae has recently emerged as a significant cause of respiratory tract disease in humans, with no obvious animal host.

The human pathogen C. trachomatis has been further subdivided into 15 serovars (A-K and L1-L3), based on the monoclonal antibodies that identify epitopes located in the major outer membrane protein (MOMP). Chlamydia trachomatis can also be classified into two biovars, based on the diseases it causes. Serovars A, B, Ba, and C have been associated with the eye disease trachoma, and serovars D, E, F, G, H, I, J, and K with genitourinary tract infections. Both diseases have worldwide distribution. Together, they are termed the trachoma biovar. The L1, L2, and L3 serovars are associated with the more invasive sexually transmitted disease (STD) lymphogranuloma venereum (LGV), which is prevalent in sub-Saharan Africa, South America, and Southeast Asia (the LGV biovar).

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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