Real-time Estimation of Mannitol-Induced Blood-Brain-Barrier Disruption by Microdialysis

We have done a study for the real-time changes of blood-brain-barrier disruption(BBBD) with brain cortical microdialysis induced by intra-carotid mannitol infusion and of cortical blood flow with laser Doppler flowmetry. A microdialysis probe was established on the right parietal cortex with 99mTc-DTPA(500 Da) as a marker, and two laser Doppler probes on the bilateral frontal cortex. Intra-carotid administration of mannitol was followed in 3 rats and intra-arterial infusion of isotonic saline in 3 control rats. Cortical blood flows were increased dramatically by about 270% to 310% from the preinfusion state within 5 minutes after mannitol infusion as compared to an average of 150% increase in saline controls. BBBd-induced extravascular leakage of 99mTc-DTPA sampled by microdialysis and estimated by high pressure liquid chromatography increased dramatically within 2 minutes, maximally about 10 times that of the pre-infusion state within 5-10 minutes after infusion, and decreased rapidly about next 20 minutes but was still more than 4 times the pre-infusion state, and slowed to near preinfusion state during the next 40-60 minutes. This result suggests the real changes of BBBD estimated by brain cortical microdialysis were relatively comparable to previous radioisotope measurement and the first 20 minutes was significantly valuable for administration of certain molecules using BBBD induced by intra-arterial mannitol infusion.

The Effects of Multiple UVB Exposures on Proliferation and Melanization in Cultured Human Melanocytes / 대한피부과학회지

BACKGROUND: In the skin, the major stimulus for cutaneous pigmentation is ultraviolet radiation. The most important physiologic role of melanin is protection against harmful UV radiation to skin. It is known there are some differences in melanization between a single and multiple exposures of UVB, in vivo. Little if known about the functions of the melanocyte alone in cutaneous pigmentation after ultraviolet exposure, because of the complexity of interactions in the whole epidermis. OBJECTIVE: To investigate the effects of multiple exposures at various dosages of UVB, and to compare the effect of UVB in multiple divided exposures with a single exposure at the same total dosage of UVB on proliferation and melanization in cultured human melanocyte. METHODS: Melanocytes were cultured by modified TIC medium. The melanoctes were exposed daily for three consecutive days to UVB at 2, 4, 8 and 16 mJ/cm2and a single exposure at 24 mJ/cm2. The morphologic changes were examined by phase contrast microscopy. The melanocytes were counted by hemocytometer and melanin contents were assayed by spectrophotometer. RESULTS: 1. The effects of multiple UVB exposures: 1) The morphologic changes were as follows: With three time exposures at a dosage of 8 mJ/cm2, themelanocytes enlarged in size, and elongated their dendrites slightly; with three time exposures at a dosage of 16 mJ/cm2, enlargement in sized and elongation of dendrited were more significant. 2) With three time exposures at dosages of 2 nd 4 mJ/cm2, the proliferation of melanocytes was stiumlated significantly(p<0.05). However, with three time exposures at dosages of 8 and 16 mJ/cm2the proliferation was inhibited(p<0.05). 3) With three time exposures at dosages of 2 and 4 mJ/cm2, the melanin contents were decreased. However, with three tiem exposures at a dosage of 16 mJ/cm2, the melanin contents were highly increased(p<0.01). 2. The comparison between multiple divided exposures and a single exposure at the same toal dosage of UVB: 1) There were no morphologic differences of dendrities between with three time exposures at a dosage of 8 mJ/cm2 and with a single exposure at a dosage of 24 mJ/cm2. However enlarged melanocytes were more numerous with a single exposure. 2) The proliferation of melanocytes was more inhibited with a single exposure than with multiple divided exposures(p<0.05). 3) The melanin contents were more increased with a single exposure than with multiple divided exposures(p<0.05). CONCLUSION: With multiple exposures at lower dosages of UVB, the proliferation of melanocytes was stimulated, and melanization was decreased. However, with multiple exposures at higher dosages of UVB, the proliferation was inhibited, and melanization was increased. At the same total dosage of UVB, the proliferation was more inhibited, and the melanization was more increased with a single exposure than with multiple divided exposures.