The proteome of human brain microdialysate

BACKGROUND: Cerebral microdialysis has been established as a monitoring tool in neurocritically ill patients suffering from severe stroke. The technique allows to sample small molecules in the brain tissue for subsequent biochemical analysis. In this study, we investigated the proteomic profile of human cerebral microdialysate and if the identified proteins might be useful predictors for disease characteristics in stroke for tissue at risk in the contralateral hemisphere. We analysed cerebral protein expression in microdialysate from three stroke patients sampled from the hemisphere contralateral to the lesion. Using a proteomic approach based on two-dimensional gel electrophoresis and subsequent mass spectrometry, we created a protein map for the global protein expression pattern of human microdialyste. RESULTS: We found an average of 158 ± 24 (N = 18) protein spots in the human cerebral microdialysate and could identify 95 spots, representing 27 individual proteins. Most of these have been detected in human cerebrospinal fluid before, but 10 additional proteins mainly of cerebral intracellular origin were identified exclusively in the microdialysate. CONCLUSIONS: The 10 proteins found exclusively in human cerebral microdialysate, but not in cerebrospinal fluid, indicate the possibility to monitor the progression of the disease towards deterioration. The correlation of protein composition in the human cerebral microdialysate with the patients' clinical condition and results of cerebral imaging may be a useful approach to future applications for neurological stroke diagnosis, prognosis, and treatment

Stable oxygen and carbon isotope ratios of Neogloboquadrina pachyderma from Latest Pleistocene to Holocene sediments of the eastern central Arctic Ocean

A high-resolution study including oxygen and carbon stable isotopes as well as carbonate and total organic carbon contents, has been performed on undisturbed near-surface (0-40 cm) sediment sequences taken in the eastern Arctic Ocean during the international Arctic 91 Expedition. Based on the oxygen stable isotope records measured on Neogloboquadrina pachyderma (sin.) and AMS 14C dating, the upper 10 to 20 cm of the sediment sequences represent isotope stage 1, and the base of Termination I (15.7 ka) can be identified very well. Stage 1 sedimentation rates vary between 0.4 and >2.0 cm/kyr. In general, glacial stage 2 sedimentation rates are probably lower and vary between 0.4 and 0.7 cm/kyr. The glacial-interglacial shifts in delta18O values of N. pachyderma sin. may reach values of 1.3 to 2.5 per mil indicating (1) that, in addition to the glacial-interglacial global ice-volume signal, changes in surface-water salinity have effected the isotope records and (2) that these salinity changes have varied laterally. Glacial-interglacial differences in salinity were small in the Lomonosov Ridge area (0-0.4 per mil) and relatively high in the Morris-Jesup-Rise area (up to 1.4 per mil). This implies that the supply of low-saline waters onto the Eurasian shelves and its further transport into the central Arctic Ocean via the Transpolar Drift should have continued during the last glacial and should have significantly influenced the surface water characteristics in parts of the central Arctic. On the Morris-Jesup-Rise, on the other hand, the glacial low-saline-water signal at that time was strongly reduced in comparison to the modern situation. At the glacial-interglacial stage 1/2 boundary, a strong meltwater signal is recorded in a sharp depletion in delta18O as well as delta13C. This central Arctic Ocean meltwater event can be correlated from the Makarov Basin through the Lomonosov Ridge and Amundsen Basin to the eastern Gakkel Ridge. The beginning of this event is AMS 14C dated at 15.7 ka, i.e., significantly older than the major decrease in the global ice-volume signal which occurs between 9 and 13.5 ka. Large amounts of freshwater/meltwater were probably supplied from the Eurasian continent due to the decay of the Barents-Sea-Ice-Sheet, causing this distinct early meltwater anomaly in the central Arctic Ocean. The extension of a well-oxygenated surface-near water mass in the Arctic Ocean and (at least seasonal) open-ice conditions and some increased bioproductivity were probably established at the end of Termination I, as indicated by the increase in delta13C to modern values as well as increased carbonate (i.e., foraminifers, coccoliths, ostracodes) and total organic carbon contents