Biography:

In the past Christian Bauer has collaborated on articles with Armin Kurtz and Gerolf Gros. One of their most recent publications is Heterotropic interactions in monomeric βSH chains from human hemoglobin. Which was published in journal Archives of Biochemistry and Biophysics.

More information about Christian Bauer research including statistics on their citations can be found on their Copernicus Academic profile page.

Christian Bauer's Articles: (25)

Heterotropic interactions in monomeric βSH chains from human hemoglobin

AbstractThe O2 affinity of βSH chains is lowered by H+, inositol hexaphosphate (IHP), and CO2. As the oxygen affinity of βSH monomers (β1SH) is lower than that of βSH tetramers (β4SH), it is possible that IHP and CO2 exert their influence on the O2 affinity of βSH chains by increasing the dissociation constant of β4SH rather than by a direct effect on the molecule. In order to test for this hypothesis we have measured the O2 affinity of βSH chains as a function of protein concentration at various concentrations of IHP and inorganic phosphates in the absence and presence of CO2. From these data association constants for the binding of IHP to β1SH and β4SH as well as for the equilibrium 4β1SH ⇌ β4SH were calculated. We found that IHP and CO2 influence the oxygen affinity of β1SH. It was furthermore established that inorganic phosphate enhances the stability of β4SH while IHP favors its dissociation in monomers.

High pK value of the N-terminal amino group of the γ-chain causes low CO2 binding of human fetal hemoglobin

AbstractThe N-terminal amino acid residue of the γ-chains of human fetal hemoglobin (Hb FII) is glycine rather than valine like in many other hemoglobins including the human adult pigment (Hb A). In the course of an evaluation of functional implications associated with this replacement we have studied the CO2 binding properties of Hb FII in comparison with Hb FIc where the N-termini of the γ-chains are blocked. By comparing Hb FII and Hb FIc it is possible to specifically estimate carbamate formation at the N-termini of the γ-chains in Hb FII. These data were used to calculate the carbamate equilibrium and ionization constant of these groups. At 37 °C, −log10 of the ionization constant (pKz) was found to be 8.1 and is thus significantly higher than pKz of the N-terminal valines of the β-chains of Hb A which has been reported to be 6.6 at 37 °C. The high pKz value of the γ-chain α-amino group explains the much lower carbamate formation in Hb FII compared to Hb A.

Heterotropic interactions in monomeric βSH chains from human hemoglobin

AbstractThe O2 affinity of βSH chains is lowered by H+, inositol hexaphosphate (IHP), and CO2. As the oxygen affinity of βSH monomers (β1SH) is lower than that of βSH tetramers (β4SH), it is possible that IHP and CO2 exert their influence on the O2 affinity of βSH chains by increasing the dissociation constant of β4SH rather than by a direct effect on the molecule. In order to test for this hypothesis we have measured the O2 affinity of βSH chains as a function of protein concentration at various concentrations of IHP and inorganic phosphates in the absence and presence of CO2. From these data association constants for the binding of IHP to β1SH and β4SH as well as for the equilibrium 4β1SH ⇌ β4SH were calculated. We found that IHP and CO2 influence the oxygen affinity of β1SH. It was furthermore established that inorganic phosphate enhances the stability of β4SH while IHP favors its dissociation in monomers.

Heterotropic interactions in monomeric βSH chains from human hemoglobin

AbstractThe O2 affinity of βSH chains is lowered by H+, inositol hexaphosphate (IHP), and CO2. As the oxygen affinity of βSH monomers (β1SH) is lower than that of βSH tetramers (β4SH), it is possible that IHP and CO2 exert their influence on the O2 affinity of βSH chains by increasing the dissociation constant of β4SH rather than by a direct effect on the molecule. In order to test for this hypothesis we have measured the O2 affinity of βSH chains as a function of protein concentration at various concentrations of IHP and inorganic phosphates in the absence and presence of CO2. From these data association constants for the binding of IHP to β1SH and β4SH as well as for the equilibrium 4β1SH ⇌ β4SH were calculated. We found that IHP and CO2 influence the oxygen affinity of β1SH. It was furthermore established that inorganic phosphate enhances the stability of β4SH while IHP favors its dissociation in monomers.

High pK value of the N-terminal amino group of the γ-chain causes low CO2 binding of human fetal hemoglobin

AbstractThe N-terminal amino acid residue of the γ-chains of human fetal hemoglobin (Hb FII) is glycine rather than valine like in many other hemoglobins including the human adult pigment (Hb A). In the course of an evaluation of functional implications associated with this replacement we have studied the CO2 binding properties of Hb FII in comparison with Hb FIc where the N-termini of the γ-chains are blocked. By comparing Hb FII and Hb FIc it is possible to specifically estimate carbamate formation at the N-termini of the γ-chains in Hb FII. These data were used to calculate the carbamate equilibrium and ionization constant of these groups. At 37 °C, −log10 of the ionization constant (pKz) was found to be 8.1 and is thus significantly higher than pKz of the N-terminal valines of the β-chains of Hb A which has been reported to be 6.6 at 37 °C. The high pKz value of the γ-chain α-amino group explains the much lower carbamate formation in Hb FII compared to Hb A.

A new candidate for the regulation of erythropoiesis: Insulin-like growth factor I

AbstractThe effect of pure human insulin-like growth factor I (IGF I) on the colony formation of late stage erythroid precursor cells (CFU-e) from fetal mouse liver and adult bone marrow was studied in a serum-free culture system. We found that IGF I in physiological concentrations stimulated erythroid colony formation. The combined effect of IGF I and erythropoietin was smaller than the sum of their single effects. The number of colonies induced by IGF I was linearly dependent on the number of plated cells. Our results indicate that IGF I is the first early defined mitogen that stimulates the late stages of erythroid differentiation independently of erythropoietin.

The cytochrome ba complex from the thermoacidophilic crenarchaeote Acidianus ambivalens is an analog of bc1 complexes

AbstractA novel cytochrome ba complex was isolated from aerobically grown cells of the thermoacidophilic archaeon Acidianus ambivalens. The complex was purified with two subunits, which are encoded by the cbsA and soxN genes. These genes are part of the pentacistronic cbsAB–soxLN–odsN locus. The spectroscopic characterization revealed the presence of three low-spin hemes, two of the b and one of the as-type with reduction potentials of + 200, + 400 and + 160 mV, respectively. The SoxN protein is proposed to harbor the heme b of lower reduction potential and the heme as, and CbsA the other heme b. The soxL gene encodes a Rieske protein, which was expressed in E. coli; its reduction potential was determined to be + 320 mV. Topology predictions showed that SoxN, CbsB and CbsA should contain 12, 9 and one transmembrane α-helices, respectively, with SoxN having a predicted fold very similar to those of the cytochromes b in bc1 complexes. The presence of two quinol binding motifs was also predicted in SoxN. Based on these findings, we propose that the A. ambivalens cytochrome ba complex is analogous to the bc1 complexes of bacteria and mitochondria, however with distinct subunits and heme types.

Full length articleCharacterization of an IgG monoclonal antibody targeted to both tissue cyst and sporocyst walls of Toxoplasma gondii

Highlights•We generated IgG mouse monoclonal antibodies directed against antigens of Toxoplasma gondii oocysts.•MAb K8/15-15 recognized antigens in both sporocyst and tissue cyst walls of T. gondii.•MAb K8/15-15 reacted against antigens in cyst walls of some related coccidia.•Sporocyst walls of Hammondia hammondi, Hammondia heydorni, and Cystoisospora felis were also labeled by mAb K8/15-15.•An additional monoclonal antiboddy (G1/19) reacted solely with T. gondii sporozoites.

Research paperFastDC derived from human monocytes within 48 h effectively prime tumor antigen-specific cytotoxic T cells☆

AbstractPreviously, we have shown that dendritic cells (DCs) with full T-cell stimulatory capacity can be derived from human monocytes after 48 h of in vitro culture (FastDC). Compared to a standard 7-day protocol, this new strategy not only reduces the time span and the amount of recombinant cytokines required, but may also resemble DC development in vivo more closely. Using a melanoma antigen model, we show here that FastDC prime CTL responses against tumor antigens as effectively as standard monocyte-derived DCs (moDCs). FastDC and moDCs derived from monocytes of HLA-A2+ donors were loaded with the melanoma-associated, HLA-A*0201-restricted peptide Melan-A and cocultured with autologous CD3+ T cells. After two weekly restimulations with freshly prepared, peptide-loaded FastDC or moDCs, binding of CD8+ T cells to fluorescently labeled MHC-I/Melan-A-peptide complexes and intracellular cytokine staining revealed that the two DC preparations had an equal capacity to prime Melan-A-specific, IFN-γ producing CD8+ T cells. CTLs derived from cocultures with FastDC lysed Melan-A-loaded T2 cells even more effectively than CTLs primed by moDCs. Comparative analysis also revealed that FastDC possess an equal capacity to migrate in response to the chemokine receptor CCR-7 ligand 6Ckine. Importantly, DCs can be generated with higher yield and purity using the FastDC-protocol. The reliability and efficacy of this new strategy for DC development from monocytes may facilitate clinical investigation of DC-based tumor immunotherapy.

Research paperCombined use of toll-like receptor agonists and prostaglandin E2 in the FastDC model: Rapid generation of human monocyte-derived dendritic cells capable of migration and IL-12p70 production

AbstractPhenotypical maturation, IL-12p70 production and migration upon chemokine receptor CCR7 ligation are currently proposed as requirements for the use of human monocyte-derived dendritic cells (DC) in antitumoral vaccination. We have previously described a short-term protocol for DC generation from monocytes including stimulation with TNF-α, IL-1β and PGE2 (FastDC). These “conventional” FastDC are mature, migrate in response to CCR7 ligation and effectively stimulate autologeous T cells in vitro, but are deficient in IL-12p70 production. Here, conventional FastDC were compared to FastDC activated with different TLR ligands. High levels of IL-12p70 were induced by combined activation of FastDC with TLR4 and TLR7/8 ligands. IL-12 secretion could be maximized by additional T cell-derived stimulation. However, TLR-stimulated FastDC failed to migrate upon CCR7 ligation, independent of additional activation with CD40 ligand and IFN-γ. The presence of PGE2 during TLR ligation fully restored migratory capacity of FastDC, but left IL-12p70 production and activation of tumor antigen-specific cytotoxic T cells unaffected, challenging previous findings obtained with standard 7-day monocyte-derived DC. The FastDC model thus not only represents an effective tool for antitumoral vaccination, but may also provide novel insights into human DC biology.

Laboratory InvestigationRenal mesangium is a target for calcitonin gene-related peptide

Renal mesangium is a target for calcitonin gene-related peptide. Rat calcitonin gene-related peptide (CGRPα; EC50, 1 nM) was shown to stimulate cAMP formation in cultured rat renal mesangial cells. CGRP concentration dependently (EC50, 1 nM) also inhibited contraction of mesangial cells by angiotensin II (10 nivi). Angiotensin II (10 nM) caused a transient increase of the intracellular calcium concentration from 140 nM to 480 nM in the mesangial cells, but these calcium transients were not altered by CGRP. CGRP (10 nM) decreased vascular resistance in the isolated rat kidney perfused at constant pressure (100 mm Hg; P < 0.01). The decreased vascular resistance was accompanied by a rise of the glomerular filtration fraction. CGRP, moreover, attenuated the effects of angiotensin II on renal vascular resistance and glomerular filtration (P < 0.01). In conclusion, CGRP causes relaxation of renal mesangial cells and decreases renal vascular resistance. As a result CGRP raises glomerular filtration and the filtration fraction. The effect may be linked to cyclic AMP formation. Thus, regulation of renal vascular and glomerular function may represent a novel action of CGRP apart from its cardiovascular effects.

Exchange rate dynamics in a target zone—A heterogeneous expectations approach

AbstractWe present a simple behavioral model with chartists and fundamentalists and analyze their trading behavior in both a floating and a target zone exchange rate regime. When applied to the floating regime, the model replicates the well-known stylized facts, such as excess volatility, fat tails, volatility clustering, and exchange rate disconnect. Our main result is that when applied to a credible target zone, our model predicts that the exchange rate remains in the center of the band for a considerable period, even though the fundamental exchange rate does not exhibit mean reversion tendencies. This is consistent with the empirical evidence and contrasts with the traditional target zone model based on Krugman [1991. Target zones and exchange rate dynamics. Quarterly Journal of Economics 16, 669–682], which predicts that the exchange rate in a target zone clusters close to the edges of the band. The hump-shaped distribution of the exchange rate obtained in our model greatly reduces the frequency of central bank intervention. We also conclude that the introduction of a target zone regime significantly reduces exchange rate volatility by decreasing speculative activity in the FX market.

Echinococcus multilocularis infections in domestic dogs and cats from Germany and other European countries

AbstractA cross-sectional survey was conducted to estimate the prevalence of Echinococcus multilocularis and E. granulosus infections in domestic dogs and cats from Germany and other European countries. Faecal samples of 21,588 dogs and 10,650 cats routinely submitted to a private veterinary laboratory between June 2004 and June 2005 were examined using the ZnSO4–NaCl flotation method. Taeniid eggs were detected in 54 (0.25%) and 37 (0.34%) of the canine and feline faecal samples, respectively. Taeniid eggs were separated and subjected to a DNA preparation and a modified two-step PCR for the detection of Echinococcus spp. based on mitochondrial 12S rRNA genes. PCR products from Echinococcus-negative but cestode-positive reactions were cloned and sequenced to determine the Taenia species. E. multilocularis DNA was specifically amplified in 43 (0.24%) and 25 (0.23%) of the samples from dogs and cats, respectively. E. granulosus DNA was not detected in any sample, while, E. multilocularis-positive samples were detected in dogs from Germany only, those of cats originated from Germany, Denmark and The Netherlands. The prevalence of E. multilocularis egg-positive canine samples was significantly higher in southern (0.35%) than in northern Germany (0.13%). In contrast, no significant regional difference was observed in cats from Germany. Taeniid eggs from Echinococcus-negative samples and from a few samples with macroscopically detected Taenia sp. proglottids were identified as eggs of T. crassiceps (n = 8), T. martis, T. serialis, T. polyacantha, T. taeniaeformis and T. pisiformis in dogs (n = 1 of each) and T. taeniaeformis (n = 11) in cats. The spectrum of cestodes detected in domestic dogs and cats indicate the consumption of small rodents as infection source. The high proportion of E. multilocularis-positive samples, suggest domestic dogs and cats as a possible source of E. multilocularis infection for humans.

Gasterophilus spp. infections in horses from northern and central Kazakhstan

Highlights•This is the first study on gastrointestinal parasites of horses in Central Asian countries since the dissolution of the Soviet Union.•Four Gasterophilus spp. (G. haemorrhoidalis, G. intestinalis, G. nasalis, G. pecorum) were found in northern and central provinces of Kazakhstan.•All horses were infected with 2nd and 3rd stage larvae throughout the year, indicates that two overlapping generations of botflies exist in the Kazakh steppe during a year.•The larval burdens were extremely high, and 22% of the horses harboured >1000 Gasterophilus spp. larvae each.

A Cheap Lunch for Emerging Markets: Removing International Financial Market Imperfections with Modern Financial Instruments

SummaryThis paper develops a market-based procedure to significantly reduce the indebtedness of emerging markets by applying an asset-backed security approach to a pool of emerging market bonds. In an extensive simulation study based on historical data, the cumulated interest savings over a horizon of 10 years amount to about 20% of the credit sum on average (with a standard deviation of 8%) and up to 44% for individual countries—dependent on the internal distribution of the surplus. The theoretical structure of the transaction is explicitly derived in cooperation with professionals from major commercial banks, and it implies only negligible implementation cost. The implementation requires neither institutional reforms nor debt forgiveness, but can supplement or substitute previous measures.

A life-cycle perspective on automotive fuel cells☆

Highlights•Individual inventories for each fuel cell system component, current and future.•Environmental and human health burdens from fuel cell production and end-of-life.•Comparison passenger transport in fuel cell and conventional vehicles.•Fuel cell can be more critical to overall burdens than hydrogen production.•Fuel cell developments require radical but possible changes to reduce burdens.

Life Cycle Assessment of Power-to-Gas: Approaches, system variations and their environmental implications

Highlights•Complete Life Cycle Assessment of Power-to-Gas with system variations.•System expansion provides more meaningful results than subdivision.•For Power-to-Hydrogen, the type of electricity supply is essential.•For Power-to-Methane, source of CO2 and the approach applied can make a difference.•Sensitivity analysis and impacts other than climate change were explored.

Multi-objective optimization of energy arbitrage in community energy storage systems using different battery technologies

Highlights•Multi-objective optimization of energy arbitrage in community energy storage systems.•Economic feasibility from the perspective of an aggregator and a distribution system operator.•Pareto frontiers of the two objectives for each scenario and six different battery technologies.•Lithium-ion battery technologies show the best economic and environmental performance.•The combination of energy arbitrage with peak shaving shows promising potential.

Sustainability of electricity supply technology portfolio

AbstractThis paper outlines the approach to the evaluation of sustainability of current and future electricity supply options of interest for a major Swiss utility Axpo Holding AG. The motivation behind this effort has been to provide a solid basis for a state-of-the-art interdisciplinary assessment and use this framework within a dialog with a wide spectrum of stakeholders. The development and implementation of the methodology was coordinated by Axpo in co-operation with the Paul Scherrer Institut (PSI) and other scientific institutions.The evaluation covers environmental, social and economic dimensions of sustainability. Methods used include among others life cycle assessment (LCA), impact pathway approach (IPA) and probabilistic safety assessment (PSA). The associated databases developed by PSI have been extensively used, subject to major extensions necessary for analyzing the future technologies. Learning curves were employed for future cost estimates. Furthermore, particularly in the social area expert surveys were used. The results were aggregated using total (internal plus external) costs approach and multi-criteria decision analysis (MCDA). For MCDA a set of criteria and the associated indicators was established. In total 75 indicators were quantified, including 11 environmental, 33 social and 31 economic.Eighteen current and 18 future technologies have been analysed including nuclear as well as fossil and renewable technologies. Total costs were estimated for these technologies providing a clear ranking with nuclear having the lowest costs and some of the renewables showing remarkable cost reductions until 2030. This ranking is partially controversial mainly due to the limited representation of social aspects in the total costs. The results of MCDA-applications involving elicitation of preferences from a relatively homogeneous stakeholder group, i.e. 85 employees of the Axpo Group (including also NOK, EGL, CKW and Axpo IT), are summarized. In addition, sensitivity of technology ranking to preference profiles is demonstrated. Broader consideration of social factors favours renewables and depending on the specifics of preference profiles may lower the ranking of nuclear. Further applications of the MCDA-approach with various stakeholder groups are planned.

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