Biology

H. ducreyi preferentially infects keratinized stratified squamous epithelium. Epidermal microabrasions formed during sexual intercourse or otherwise damaged skin is the portal of entry for infection. After entry into the skin, the bacteria stimulate target cells such as keratinocytes, fibroblasts, and endothelial cells to secrete IL-6 and IL-8.[1] Polymorphonuclear cells are recruited within 24 hr to the epidermis and dermis and form small micropustules. A dermal infiltrate of T cells, macrophages, and some B cells evolves.[2] A tender erythematous papule may develop 4-7 days after initial infection, which can progress to the pustular stage. The bacteria remain extracellular through the pustular stage and resist phago-cytosis.[3,4] Pustules often rupture after a further 2-3 days to form painful shallow ulcers with granulomatous bases and purulent exudates.[5] In the absence of effective antimicrobial therapy, the chancroid ulceration can take several weeks to months to resolve. Inguinal lymphadenitis occurs in up to 50% of cases and the lymph nodes may develop into buboes. If not aspirated or drained through incision, buboes can rupture spontaneously.[5]

In the rabbit model, H. ducreyi does not grow at temperatures above 35°C, but only in rabbits housed at 15-17°C. In culture the bacteria grow best at 33°C, which probably reflects the fact that in humans only external surfaces are susceptible to infection. Experimental animal models for H. ducreyi that most resemble the human in vivo growth are pig and macaque models. A mouse subcutaneous chamber model was developed for studying long-term growth.[6]

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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