Vitamin D levels are associated with epistaxis severity and bleeding duration in hereditary hemorrhagic telangiectasia.

AIM: To explore the association between vitamin D levels and mild versus severe epistaxis, as well as the overall epistaxis severity score (ESS) in patients with hereditary hemorrhagic telangiectasia. PATIENTS & METHODS: A retrospective chart review of 198 patients was performed to explore the relationship between vitamin D levels and the ESS. Vitamin D levels were also compared with those with mild epistaxis to those with severe epistaxis. RESULTS: A significant difference was found between patient's vitamin D levels and their associated ESS and duration of epistaxis. Patients with mild epistaxis had higher levels of vitamin D than patients with severe epistaxis. CONCLUSION: Vitamin D is associated with features of hereditary hemorrhagic telangiectasia including ESS, bleeding time and epistaxis severity.

The role of the prostaglandin E2 receptors in vulnerability of oligodendrocyte precursor cells to death.

BACKGROUND: Activity of cyclooxygenase 2 (COX-2) in mouse oligodendrocyte precursor cells (OPCs) modulates vulnerability to excitotoxic challenge. The mechanism by which COX-2 renders OPCs more sensitive to excitotoxicity is not known. In the present study, we examined the hypothesis that OPC excitotoxic death is augmented by COX-2-generated prostaglandin E2 (PGE2) acting on specific prostanoid receptors which could contribute to OPC death. METHODS: Dispersed OPC cultures prepared from mice brains were examined for expression of PGE2 receptors and the ability to generate PGE2 following activation of glutamate receptors with kainic acid (KA). OPC death in cultures was induced by either KA, 3'-O-(Benzoyl) benzoyl ATP (BzATP) (which stimulates the purinergic receptor P2X7), or TNFα, and the effects of EP3 receptor agonists and antagonists on OPC viability were examined. RESULTS: Stimulation of OPC cultures with KA resulted in nearly a twofold increase in PGE2. OPCs expressed all four PGE receptors (EP1-EP4) as indicated by immunofluorescence and Western blot analyses; however, EP3 was the most abundantly expressed. The EP3 receptor was identified as a candidate contributing to OPC excitotoxic death based on pharmacological evidence. Treatment of OPCs with an EP1/EP3 agonist 17 phenyl-trinor PGE2 reversed protection from a COX-2 inhibitor while inhibition of EP3 receptor protected OPCs from excitotoxicity. Inhibition with an EP1 antagonist had no effect on OPC excitotoxic death. Moreover, inhibition of EP3 was protective against toxic stimulation with KA, BzATP, or TNFα. CONCLUSION: Therefore, inhibitors of the EP3 receptor appear to enhance survival of OPCs following toxic challenge and may help facilitate remyelination.