In addition to marked seasonal changes in reproductive, metabolic, and other physiological functions, many vertebrate species undergo seasonal changes in immune function. Despite growing evidence that photoperiod mediates seasonal changes in immune function, little is known regarding the neuroendocrine mechanisms underlying these changes. Increased immunity in short days is hypothesized to be due to the increase in the duration of nightly melatonin secretion, and recent studies indicate that melatonin acts directly on immune cells to enhance immune parameters. The present study examined the contribution of melatonin receptors in mediating the enhancement of splenocyte proliferation in response to the T cell mitogen Concanavalin A in mice. The administration of luzindole, a high-affinity melatonin receptor antagonist, either in vitro or in vivo significantly attenuated the ability of in vitro melatonin to enhance splenic lymphocyte proliferation during the day or night. In the absence of melatonin or luzindole, splenocyte proliferation was intrinsically higher during the night than during the day. In the absence of melatonin administration, luzindole reduced the ability of spleen cells to proliferate during the night, when endogenous melatonin concentrations are naturally high. This effect was not observed during the day, when melatonin concentrations are low. Taken together, these results suggest that melatonin enhancement of splenocyte proliferation is mediated directly by melatonin receptors on splenocytes and that there is diurnal variation in splenocyte proliferation in mice that is also mediated by splenic melatonin receptors.

Photosensitivity associated with HIV infection is an increasingly recognized dermatologic condition with a heterogeneous clinical presentation. AA ethnicity and HAART were independent indicators for the diagnosis of photosensitivity, whereas CD4+ and UV exposure had non-significant associations. The subtleties in these and other clinical variables may directly aid in the recognition and diagnosis of this poorly characterized disorder.

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This case demonstrates another example of cortical osteolysis directly adjacent to a PG ulcer in which the bony changes may be neutrophil-induced.

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Neutrophilic dermatosis of the dorsal hands (NDDH) was originally described as pustular vasculitis (PV) of the hands. Recent debate focuses on categorizing this disorder in the family of neutrophilic dermatoses (ND), as opposed to a primary vasculitis. We present a case of NDDH with clinical and histologic features consistent with ND, and discuss the major concerns for this disease's reclassification.

Bipolaris spicifera is a darkly pigmented (dematiaceous) fungus that uncommonly causes infections in humans. There are few cases of reported cutaneous Bipolaris infection in the literature. We report a case of a five-year-old boy with B-precursor-cell acute lymphoblastic leukemia who developed a cutaneous fungal infection on his left cheek Histopathological and microbiological findings identified the fungus as Bipolaris spicifera. Surgical excision and systemic antifungal therapy are the mainstay of treatment.

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