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In JoVE (1)
Other Publications (6)
Articles by Christian Schauer in JoVE
JoVE Neuroscience
Imaging Calcium Responses in GFP-tagged Neurons of Hypothalamic Mouse Brain Slices
Department of Physiology, School of Medicine, University of Saarland, Homburg, Germany
In this protocol, we update recent progress in imaging Ca2+ signals of GFP-tagged neurons in brain tissue slices using a red fluorescent Ca2+ indicator dye.
Other articles by Christian Schauer on PubMed
Polycyclic Aromatic Hydrocarbons in Urban Air Particulate Matter: Decadal and Seasonal Trends, Chemical Degradation, and Sampling Artifacts
Aerosol filter samples collected at a major urban traffic junction (LKP) and at a suburban residential location (IWC) in the metropolitan area of Munich (Germany) throughout the years 2001 and 2002 have been analyzed for 12 of the 16 EPA priority polycyclic aromatic hydrocarbon (PAH) pollutants by liquid chromatography with fluorescence detection. The mean mass concentration of the sum of all investigated PAH in the sampled air at LKP (1.9-5.0 ng m(-3)) was roughly two times higher than at IWC (0.8-2.9 ng m(-3)), and at both locations it was about 2-3 times higher in winter (heating season) than in summer and spring or autumn. Comparisons with earlier measurement campaigns indicate a steep decrease of PAH abundance by almost an order of magnitude from 1980 to 1993 and a much slower decrease since then. Distinctly different seasonal trends and short-term fluctuations have been observed for semivolatile 3- and 4-ring PAH and for particle-bound 5- and 6-ring PAH. Based on systematic correlation analyses with a wide range of air quality parameters, most of the differences can be attributed to not only varying emissions but also chemical reactions with atmospheric oxidants which were found to play an important role. The results of denuder experiments prove that substantial degradation of the particularly toxic tracer benzo[a]pyrene and of the other investigated 5- and 6-ring PAH can occur during filter sampling and on airborne particles (formation of oxygenated and nitrated derivatives). Filter reaction artifacts are shown to lead to an underestimation of the actual PAH content of urban air particulate matter by up to 100% of the measurement value or more, with a near-linear dependence on ozone volume mixing ratio. The role and applicability of ozone as a tracer of atmospheric oxidizing capacity for particle-bound PAH is discussed and confirmed by comparison with earlier investigations and by complementary laboratory experiments (reaction kinetics and product studies).
The Diesel Exhaust Component Pyrene Induces Expression of IL-8 but Not of Eotaxin
Environmental pollutants can influence the expression of immunoregulatory molecules and, in this way, promote allergies. The local synthesis of proinflammatory chemokines is an important aspect in the development of allergic airway inflammation. We have characterized the influence of pyrene, a polycyclic aromatic hydrocarbon (PAH) contained, for example, in diesel exhaust particles (DEP), on transcription and secretion of the chemokines interleukin-8 (IL-8) and eotaxin. Reporter genes under control of the respective promoters were tested in the human cell lines A549 and HeLa, mRNA production was assayed in A549 cells and protein production was measured by ELISA in cell supernatants from primary human fibroblasts. Pyrene content of cell supernatants was measured by analytical HPLC. Promoter activity, mRNA production and protein expression of IL-8 were increased by pyrene. The activating effect in reporter gene studies was abolished by mutating either an NF-kappaB or an AP-1 binding site in the IL-8 promoter. In contrast, pyrene showed no effect on transcription from the eotaxin promoter, despite the important role of this chemokine in asthma. Our data show that pyrene has specific effects on chemokine synthesis, which are not restricted to mediators primarily associated with atopic diseases. Pyrene also affected cells not derived from lung tissue, which suggests a broader immunoregulatory influence for this pollutant.
Analysis of Nitrated Polycyclic Aromatic Hydrocarbons by Liquid Chromatography with Fluorescence and Mass Spectrometry Detection: Air Particulate Matter, Soot, and Reaction Product Studies
Polycyclic aromatic hydrocarbons (PAH) and their nitrated derivatives (nitro-PAH) are environmental pollutants which pose a threat to human health even at low concentration levels. In this study, efficient analytical methods for the analysis of nitro-PAH and PAH (extraction, clean-up, chromatographic separation, and spectrometric detection) have been developed, characterized, and applied to aerosol samples. The separation and quantification of 12 nitro-PAH was carried out by reversed-phase high performance liquid chromatography (HPLC), on-line reduction, and fluorescence detection. The detection limits were in the range of 0.03-0.5 microg L(-1) (6-100 pg in the investigated sample aliquots), and the recovery rates from soot samples were 70-90%. Nitro-PAH and PAH concentrations have been determined for different types of soot and for urban, rural, and alpine fine air particulate matter (PM2.5). For the first time, trace amounts of nitro-PAH have been detected in a high-alpine clean air environment. The on-line reduction and fluorescence technique has been complemented by atmospheric pressure chemical ionization time-of-flight mass spectrometry (APCI-TOF-MS). The MS detection allowed the analysis of partially nitrated and oxygenated PAH in laboratory studies of the heterogeneous reaction of PAH on soot and glass fiber substrates with gaseous nitrogen oxides and ozone. It led to the tentative identification of a previously unknown nitrated derivative of the particularly toxic PAH benzo[ a]pyrene (BaP-nitroquinone), and provides the first experimental evidence that PAH-nitroquinones can be formed by reaction of PAH with atmospheric photooxidants.
Pros and Cons of Intraperitoneal Chemotherapy in the Treatment of Epithelial Ovarian Cancer
Development of the pros and cons of intraperitoneal (IP) chemotherapy in the treatment of epithelial ovarian cancer based on the most prominent data published on the evolution of IP chemotherapy and on experience with this therapeutic strategy in clinical routine. The literature published on IP chemotherapy in ovarian cancer between 1970 and 2008 was identified systematically by computer-based searches in MEDLINE and the Cochrane Library. Furthermore, a preliminary analysis of data recorded during an observational nationwide multicenter study of the Austrian AGO on IP-IV chemotherapy using the GOG-172 treatment regimen was performed. The literature review unequivocally revealed a significantly greater toxicity for IP than for intravenous (IV) cisplatin-based chemotherapy. However, according to a Cochrane meta-analysis, IP-IV administration of chemotherapy is associated with a 21.6% decrease in the risk for death. In agreement with earlier reports, the most frequently mentioned side-effects in the Austria-wide observational study were long-lasting neurotoxicity, abdominal pain, fatigue, gastrointestinal and metabolic toxicities, and catheter-related complications. Most of these toxicities were identified as mirroring the toxicity profile of high-dose IV cisplatin (>or=100 mg/m(2)). In some patients, the classic IP-IV regimen with cisplatin/paclitaxel was changed to an alternative schedule comprising carboplatin AUC 5 (d1) and weekly paclitaxel 60 mg/m(2) (d1, 8, 15) completely administered via the IP route. This treatment was better tolerated and quality of life was significantly less compromised. However, neutropenia and thrombocytopenia were the limiting side-effects of this IP regimen. In cases where optimal cytoreduction with residual disease
Clinical Consequences of the Calypso Trial Showing Superiority of PEG-liposomal Doxorubicin and Carboplatin over Paclitaxel and Carboplatin in Recurrent Ovarian Cancer: Results of an Austrian Gynecologic Oncologists' Expert Meeting
The Calypso trial showed an improved progression-free survival with PEG-liposomal doxorubicin (PLD) and carboplatin (P) as compared with the standard regimen paclitaxel (PCLTX) and P in the second- or third-line treatment of platinum-sensitive epithelial ovarian cancer [1]. A panel of Austrian gynecologic oncologists discussed the clinical consequences of the data from the Calypso study for the routine practice. PLD + P had a significantly lower rate of alopecia and neuropathy than the taxane regimen, both toxicities which compromise the quality of life. Due to possible significant thrombocytopenia, the blood counts of patients undergoing PLD + P therapy should be monitored weekly. Patients receiving PLD/P are at higher risk of nausea and vomiting. Palmoplantar erythrodysesthesia (hand-foot syndrome) is a significant toxicity of PLD + P most prevalent after the third or fourth cycle. Prophylaxis consists of avoiding pressure on feet and hands and other parts of the body. Similarly, prophylaxis of mucositis seems important and includes avoiding consumption of hot, spicy and salty foods and drinks. Mouth dryness should be avoided. Premedication with antiemetics and dexamethasone dissolved in 5% glucose is done to prevent hypersensitivity to PLD. In conclusion, the therapeutic index is more favorable for PLD + P than for PCTX + P.
Genetic Identification of GnRH Receptor Neurons: a New Model for Studying Neural Circuits Underlying Reproductive Physiology in the Mouse Brain
GnRH signaling regulates reproductive physiology in vertebrates via the hypothalamic-pituitary-gonadal axis. In addition, GnRH signaling has been postulated to act on the brain. However, elucidating its functional role in the central nervous system has been hampered because of the difficulty in identifying direct GnRH signaling targets in live brain tissue. Here we used a binary genetic strategy to visualize GnRH receptor (GnRHR) neurons in the mouse brain and started to characterize these cells. First, we expressed different fluorescent proteins in GnRHR neurons and mapped their precise distribution throughout the brain. Remarkably, neuronal GnRHR expression was only initiated after postnatal day 16, suggesting peri- and postpubertal functions of GnRH signaling in this organ. GnRHR neurons were found in different brain areas. Many GnRHR neurons were identified in areas influencing sexual behaviors. Furthermore, GnRHR neurons were detected in brain areas that process olfactory and pheromonal cues, revealing one efferent pathway by which the neuroendocrine hypothalamus may influence the sensitivity towards chemosensory cues. Using confocal Ca(2+) imaging in brain slices, we show that GnRHR neurons respond reproducibly to extracellular application of GnRH or its analog [D-TRP(6)]-LH-RH, indicating that these neurons express functional GnRHR. Interestingly, the duration and shape of the Ca(2+) responses were similar within and different between brain areas, suggesting that GnRH signaling may differentially influence brain functions to affect reproductive success. Our new mouse model sets the stage to analyze the next level of GnRH signaling in reproductive physiology and behavior.
