Oxidative stress modulates nucleobase transport in microvascular endothelial cells.

Purine nucleosides and nucleobases play key roles in the physiological response to vascular ischemia/reperfusion events. The intra- and extracellular concentrations of these compounds are controlled, in part, by equilibrative nucleoside transporter subtype 1 (ENT1; SLC29A1) and by equilibrative nucleobase transporter subtype 1 (ENBT1). These transporters are expressed at the membranes of numerous cell types including microvascular endothelial cells. We studied the impact of reactive oxygen species on the function of ENT1 and ENBT1 in primary (CMVEC) and immortalized (HMEC-1) human microvascular endothelial cells. Both cell types displayed similar transporter expression profiles, with the majority (>90%) of 2-chloro[(3)H]adenosine (nucleoside) uptake mediated by ENT1 and [(3)H]hypoxanthine (nucleobase) uptake mediated by ENBT1. An in vitro mineral oil-overlay model of ischemia/reperfusion had no effect on ENT1 function, but significantly reduced ENBT1 Vmax in both cell types. This decrease in transport function was mimicked by the intracellular superoxide generator menadione and could be reversed by the superoxide dismutase mimetic MnTMPyP. In contrast, neither the extracellular peroxide donor TBHP nor the extracellular peroxynitrite donor 3-morpholinosydnonimine (SIN-1) affected ENBT1-mediated [(3)H]hypoxanthine uptake. SIN-1 did, however, enhance ENT1-mediated 2-chloro[(3)H]adenosine uptake. Our data establish HMEC-1 as an appropriate model for study of purine transport in CMVEC. Additionally, these data suggest that the generation of intracellular superoxide in ischemia/reperfusion leads to the down-regulation of ENBT1 function. Modification of purine transport by oxidant stress may contribute to ischemia/reperfusion induced vascular damage and should be considered in the development of therapeutic strategies.

Immunofluorescent study of polyps in nose and paranasal cavities.

OBJECTIVES: Aim of this research was an immunofluorescent study and to measure immunoglobulins status of the polyps in the nose and paranasal cavities. BACKGROUND: Polyps of the nose and the paranasal cavities are very often guised, and their frequency is growing with increasing chemicals and allergens. These factors interfere important research on polyps. Developments in allergology and immunology help in the detection of etiopathogenetical mechanisms of polyposis development, like the disturbance in mucus immunity. METHODS: Clinical material was collected from 100 hospitalized patients at the Department for otorinolarynology, Clinical center of Nis. All patients had transnasal ethmoidectomy and polypectomy. In 19 patients trepanation of maxillary sinus (Coldwell Luc's) was made. Materials were examined by immunofluorescense. RESULTS: IgA immunofluorescency was negative in all examined parameters when examined under a ultraviolet luminescent with immunofluorescent microscope. IgM immunofluorescency was also negative in all examined parameters while IgG immunofluorescency was positive, but with different degree of intensity. The C3b fraction complement showed positive immunofluorescency in 80% with standard intensity ++++ in all examined preparations. CONCLUSION: Study of adenoids approved disarrangement in immune elimination in all examined preparations has shown very little immunity including the "second line of defense". High percent positive C3b complement fractions, with alongside emphasis on IgG response, instigate existing humoral reaction. The epithelium is very liable to many recurrent infections, wherewith beginning end of one permanent etiopathogenetical circle IgG-C3b-mastocits-eozinophils-lgA. Profusely blocked immune-eliminations and large production of mucous can cause some nasal diseases (Tab. 2, Fig. 2, Ref. 15). Full Text (Free, PDF) www.bmj.sk.