Showing papers by "University of Konstanz published in 1997"
TL;DR: Pulsed ATP/depletion/repletion experiments showed that ATP generation either by glycolysis or by mitochondria was required for the active execution of the final phase of apoptosis, which involves nuclear condensation and DNA degradation.
Abstract: Apoptosis and necrosis are considered conceptually and morphologically distinct forms of cell death Here, we report that demise of human T cells caused by two classic apoptotic triggers (staurosporin and CD95 stimulation) changed from apoptosis to necrosis, when cells were preemptied of adenosine triphosphate (ATP) Nuclear condensation and DNA fragmentation did not occur in cells predepleted of ATP and treated with either of the two inducers, although the kinetics of cell death were unchanged Selective and graded repletion of the extramitochondrial ATP/pool with glucose prevented necrosis and restored the ability of the cells to undergo apoptosis Pulsed ATP/depletion/repletion experiments also showed that ATP generation either by glycolysis or by mitochondria was required for the active execution of the final phase of apoptosis, which involves nuclear condensation and DNA degradation
1,884 citations
TL;DR: S syntrophically fermenting bacteria synthesize ATP by substrate-level phosphorylation and reinvest part of the ATP-bound energy into reversed electron transport processes, to release the electrons at a redox level accessible by the partner bacteria and to balance their energy budget.
Abstract: Fatty acids and alcohols are key intermediates in the methanogenic degradation of organic matter, e.g., in anaerobic sewage sludge digestors or freshwater lake sediments. They are produced by classical fermenting bacteria for disposal of electrons derived in simultaneous substrate oxidations. Methanogenic bacteria can degrade primarily only one-carbon compounds. Therefore, acetate, propionate, ethanol, and their higher homologs have to be fermented further to one-carbon compounds. These fermentations are called secondary or syntrophic fermentations. They are endergonic processes under standard conditions and depend on intimate coupling with methanogenesis. The energetic situation of the prokaryotes cooperating in these processes is problematic: the free energy available in the reactions for total conversion of substrate to methane attributes to each partner amounts of energy in the range of the minimum biochemically convertible energy, i.e., 20 to 25 kJ per mol per reaction. This amount corresponds to one-third of an ATP unit and is equivalent to the energy required for a monovalent ion to cross the charged cytoplasmic membrane. Recent studies have revealed that syntrophically fermenting bacteria synthesize ATP by substrate-level phosphorylation and reinvest part of the ATP-bound energy into reversed electron transport processes, to release the electrons at a redox level accessible by the partner bacteria and to balance their energy budget. These findings allow us to understand the energy economy of these bacteria on the basis of concepts derived from the bioenergetics of other microorganisms.
1,749 citations
TL;DR: It is proved that Rsym is seriously flawed, because it has an implicit dependence on the redundancy of the data, and a corrected R-factor, Rmeas, is introduced as the equivalent robust indicator of data consistency.
Abstract: The quantity Rsym (also called Rmerge) is almost universally used for describing X-ray diffraction data quality. Here, we prove that Rsym is seriously flawed, because it has an implicit dependence on the redundance of the data. A corrected R-factor, Rmeas, is introduced as the equivalent robust indicator of data consistency. In addition, we introduce Rmrgd an R-factor that reflects the gain in accuracy upon averaging of equivalent reflections, as a useful indicator of the quality of reduced data. These new data quality indicators better reveal the benefits of highly redundant data and should stimulate improvements in data quality through increased merging of data from multiple crystals.
800 citations
TL;DR: The data suggest that chronic pain is accompanied by cortical reorganization and may serve an important function in the persistence of the pain experience.
669 citations
TL;DR: A simple transition scheme has emerged from the multitude of data collected on fiber type conversions under a variety of conditions, and it is now clear that fiber type transitions do not proceed in immediate jumps from one extreme to the other, but occur in a graded and orderly sequential manner.
Abstract: Mammalian skeletal muscle is an extremely heterogeneous tissue, composed of a large variety of fiber types. These fibers, however, are not fixed units but represent highly versatile entities capable of responding to altered functional demands and a variety of signals by changing their phenotypic profiles. This adaptive responsiveness is the basis of fiber type transitions. The fiber population of a given muscle is in a dynamic state, constantly adjusting to the current conditions. The full range of adaptive ability spans fast to slow characteristics. However, it is now clear that fiber type transitions do not proceed in immediate jumps from one extreme to the other, but occur in a graded and orderly sequential manner. At the molecular level, the best examples of these stepwise transitions are myofibrillar protein isoform exchanges. For the myosin heavy chain, this entails a sequence going from the fastest (MHCIIb) to the slowest (MHCI) isoform, and vice-versa. Depending on the basal protein isoform profile and hence the position within the fast-slow spectrum, the adaptive ranges of different fibers vary. A simple transition scheme has emerged from the multitude of data collected on fiber type conversions under a variety of conditions.
651 citations
TL;DR: In this paper, the domain structure in thin films of an immiscible polystyrene/poly(methyl methacrylate) (PS/PMMA) blend was studied after spin-casting from a common solvent.
Abstract: The domain structure in thin films of an immiscible polystyrene/poly(methyl methacrylate) (PS/PMMA) blend was studied after spin-casting from a common solvent. Atomic force microscopy (AFM) combined with selective dissolution was used to obtain three-dimensional information on the domain morphology in thin films. Three different common solvents and three different substrate surfaces were studied. Distinct differences in the thin film domain structure and surface topography are observed depending on the substrate surface energy and the solubility of the two polymers in the three solvents. The topographic modulation can be explained by a different rate of solvent evaporation during spin-coating for the two phases. The normal and lateral organization of the phase-separated domains is governed by a complex interplay between preferential aggregation of one phase at the substrate and phase segregation in the film. Additionally, some of the results suggest that a dewetting process may be involved in the domain f...
573 citations
TL;DR: The authors make a distinction between compliance with norms and the diffusion mechanisms empowering them domestically, explaining variance in the latter with an institutional argument that captures key dynamics portrayed in other prominent accounts, illustrated by considering the domestic impact of norms embedded in the European human rights regime.
Abstract: In recent years, students of regimes and norms have paid greater attention to domestic politics. Both liberals and constructivists are `unpacking' the state in ways that further our understanding of how international norms work their effects in the domestic arena. A crucial next step is for adherents of these two schools to engage in dialogue. This article contributes to such an enterprise by developing scope conditions that predict when norms will have the constraining or constitutive effects favored, respectively, by liberals and constructivists. I make a distinction between compliance with norms and the diffusion mechanisms empowering them domestically, explaining variance in the latter with an institutional argument that captures key dynamics — rationalist or social constructivist — portrayed in other prominent accounts. The argument is illustrated by considering the domestic impact of norms embedded in the European human rights regime.
479 citations
TL;DR: In this paper, the complete family of squeezed states of light (states that have less uncertainty in one observable than does the vacuum state) have been generated using an optical parametric amplifier, and their density matrices and Wigner functions have been reconstructed from measurements of the quantum statistics of their electric fields.
Abstract: A state of a quantum-mechanical system is completely described by a density matrix or a phase-space distribution such as the Wigner function. The complete family of squeezed states of light (states that have less uncertainty in one observable than does the vacuum state) have been generated using an optical parametric amplifier, and their density matrices and Wigner functions have been reconstructed from measurements of the quantum statistics of their electric fields.
441 citations
TL;DR: It was found that the gross growth efficiency of planktonic protozoans and metazoans hardly differed between taxa, and the dependency of GGE on food concentrations was the most reliable relationship identified by multiple regression.
Abstract: A comprehensive datasct on the gross growth efficiency (GGE) of planktonic protozoans and metazoans was gathered from the literature in order to (1) identify typical ranges of values, (2) to reexamine the taxon specificity of GGE, and (3) to evaluate the impact of food concentration, predator-prey weight ratio, and temperature on GGE. All taxa (i.e. nano/microAagellates, dinoflagellates, ciliates, rotifers, cladocerans, and copepods) were found to have mean and median GGE of -2O-30%. Contrary to the common practice of using different values of GGE for ciliates and crustaceans, I found that the GGE hardly differed between taxa. Variability within all taxa was high and could only partially be attributed to the independent variables mentioned above. The dependency of GGE on food concentrations was the most reliable relationship identified by multiple regression. Establishing further generalizations regarding the dependency of GGE on other factors was hampered by methodological differences among studies and taxa and the lack of information on other potentially important factors such as the clemental composition of prey items. Future studies of GGE should recognize the importance of these factors. Knowledge of fluxes of matter and energy within ecosystems is a prerequisite for the understanding of food web regulation and of the role that oceans and lakes play in the global carbon cycle (Longhurst 199 1). However, quantifying carbon fluxes reliably in particular ecosystems is hampered by many difficulties. The complexity of aquatic food webs outpaces our capacity to make all the necessary measure
376 citations
TL;DR: Increasing evidence suggests that apoptosis and necrosis seem to represent only different shapes of cell demise, resulting from a more or less complete execution of the internal death program.
333 citations
TL;DR: The diffusing-wave spectroscopy (DWS) has become a particularly important quantitative tool in colloid physics because of its applicability to systems containing very high concentrations of scatterers, and its extreme sensitivity to small motions as mentioned in this paper.
Abstract: Since its invention about a decade ago, dynamic multiple light scattering has found many applications in various areas of soft condensed matter science. It has become a particularly important quantitative tool in colloid physics because of its applicability to systems containing very high concentrations of scatterers, and its extreme sensitivity to small motions. Recent advances of this technique, currently called diffusing-wave spectroscopy because of the diffusive transport of the light waves, include remote optical measurements of frequency-dependent viscoelasticity, studies of the microscopic dynamical processes in flowing sand and aging foam, a theoretical description of dynamic scattering from orientational fluctuations in liquid crystals and imaging of dynamic heterogeneities buried inside a turbid background medium.
01 Dec 1997-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: Multi-unit electrophysiological mapping was used to establish the area of the left- and right-hemisphere auditory cortex of the mouse and to characterize various fields within the AC, which were compared with auditory cortical maps of other mammals.
Abstract: Multi-unit electrophysiological mapping was used to establish the area of the left- and right-hemisphere auditory cortex (AC) of the mouse and to characterize various fields within the AC. The AC of the left hemisphere covered a significantly larger (factor of 1.30) area compared to that of the right side. Based on best-frequency (BF) maps and other neuronal response characteristics to tone and noise bursts, five fields (primary auditory field, anterior auditory field, second auditory field, ultrasonic field, dorsoposterior field) and two small non-specified areas could be delimited on both hemispheres. The relative sizes of these fields and areas were similar on both sides. The primary and anterior auditory fields were tonotopically organized with counter running frequency gradients merging in the center of the AC. These fields covered BF ranges up to about 45 kHz. Higher BFs up to about 70 kHz were represented non-tonotopically in the separate ultrasonic field, part of which may be considered as belonging to the primary field. The dorsoposterior and second auditory fields were non-tonotopically organized and neurons had special response properties. These characteristics of the mouse AC were compared with auditory cortical maps of other mammals.
TL;DR: Proinflammatory cytokines and IL-10 are identified as strong regulators of spontaneous neutrophil apoptosis during sepsis, which seems to be associated with alterations of signal transduction pathways.
TL;DR: The simultaneous generation of superoxide and nitric oxide proved to be as efficient as a bolus of peroxynitrite which supports a possible inactivation of prostacyclin synthase under in vivo conditions, and substantiates an often suggested crucial role ofsuperoxide in the pathophysiology of the cardiovascular system.
Abstract: Vascular tone critically depends on the endothelial release of nitric oxide and prostacyclin. Superoxide anions counteract these relaxations by trapping nitric oxide under formation of peroxynitrite. As we have recently reported, peroxynitrite is able to inhibit prostacyclin formation in aortic microsomes (Zou et al., 1996). Here we show that peroxynitrite also blocks purified prostacyclin synthase with an IC50 value of about 50 nM and with a similar sensitivity also inhibits the enzyme activity in the EaHy 926 endothelial cell line. Thromboxane synthase, having the same heme-thiolate (P450) structure and a closely-related mechanism was unaffected by peroxynitrite. Anti-nitrotyrosine antibodies reacted positive by a Western blot after treatment of the purified enzyme with 1 microM peroxynitrite. Tetranitromethane also inhibited the enzyme activity which, like the inhibition by peroxynitrite, could be partially prevented in the presence of the substrate analog U46619. The simultaneous generation of superoxide and nitric oxide proved to be as efficient as a bolus of peroxynitrite which supports a possible inactivation of prostacyclin synthase under in vivo conditions. This substantiates an often suggested crucial role of superoxide in the pathophysiology of the cardiovascular system.
TL;DR: In this paper, a method for the application of colloid monolayers to almost any surface where these difficulties are circumvented is presented, at first the monlayers are fabricated on glass substrates and afterwards floated off on a water surface.
Abstract: Hexagonally closed packed monolayers of colloids have found more and more applications, e.g. as lithographic masks. The monolayers are usually produced with the help of a self-organizing process where a suspension of colloids is applied to the desired substrate and left to dry. This method requires a good wettability and smoothness of the substrate, which severely limits the number of possible substrates. We present a new method for the application of colloid monolayers to almost any surface where these difficulties are circumvented. At first the monolayers are fabricated on glass substrates and afterwards floated off on a water surface. From there, they are transferred to the desired substrate. Examples where transferred monolayers were used as lithographic masks are shown on glass, indium tin oxide, and tungsten diselenide. The transfer of a colloid monolayer to a copper grid for transmission electron microscopy demonstrates the applicability of the technique to curved surfaces as well.
TL;DR: The data point to a direct link between the CK-PCr system and Ca2+-flux regulation during the excitation and relaxation phases of muscle contraction.
TL;DR: Protein complexes isolated from detergent solubilised rat brain extracts, containing octameric mitochondrial creatine kinase, porin and the adenine nucleotide translocator were reconstituted into malate loaded lipid vesicles and induced a cyclosporin A sensitive malate release.
TL;DR: In this article, the quantum-mechanical analogue of the classical phase-space distribution function was used to show that the motion of atoms behaves in a strongly non-classical manner.
Abstract: Beams of atoms can exhibit interference and diffraction phenomena just like waves of light. For a coherent beam of helium atoms in a double-slit experiment, measurements of the quantum-mechanical analogue of the classical phase-space distribution function show that the motion of atoms behaves in a strongly non-classical manner.
TL;DR: Reggie-1 and reggie-2 are identified as neuronal surface proteins, present on newly differentiated ganglion cells at the retinal margin and which are reexpressed in mature ganglION cells upon injury and during axonal regeneration.
Abstract: Fish--in contrast to mammals--regenerate retinal ganglion cell axons when the optic nerve is severed. Optic nerve injury leads to reexpression of proteins, which typically are first expressed in newly differentiated retinal ganglion cells and axons. Here we identified two new proteins of fish retinal ganglion cells, reggie-1 and reggie-2, with monoclonal antibody M802 and molecular cloning techniques. In normal fish, M802 stained the few retinal axons derived from newborn ganglion cells which in fish are added lifelong to the retinal margin. After optic nerve injury, however, M802 labeled all retinal ganglion cells and retinal axons throughout their path into tectum. Consistent with M802 staining, reggie-1 and reggie-2 mRNAs were present in lesioned retinal ganglion cells, as demonstrated by in situ hybridization, but were not detectable in their normal mature counterparts. In western blots with membrane proteins of the adult goldfish brain, M802 recognizes a 48x10(3) Mr protein band. At the amino acid level, 48x10(3) Mr reggie-1 and reggie-2 are 44% identical, lack transmembrane and membrane anchor domains, but appear membrane associated by ionic interactions. Reggie-1 and reggie-2 are homologous to 35x10(3) Mr ESA (human epidermal surface antigen) but are here identified as neuronal surface proteins, present on newly differentiated ganglion cells at the retinal margin and which are reexpressed in mature ganglion cells upon injury and during axonal regeneration.
TL;DR: Analysis of ultrathin sections from isolated bovine chromaffin cells grown on plastic support, after fast freezing, by quantitative electron microscopy determined the size and intracellular distribution of dense core vesicles (DVs or Chromaffin granules) and of clear vesicle (CVs) and found that DVs appear randomly packed inside cells.
Abstract: We have analyzed ultrathin sections from isolated bovine chromaffin cells grown on plastic support, after fast freezing, by quantitative electron microscopy. We determined the size and intracellular distribution of dense core vesicles (DVs or chromaffin granules) and of clear vesicles (CVs). The average diameter of DVs is 356 nm, and that of CVs varies between 35-195 nm (average 90 nm). DVs appear randomly packed inside cells. When the distance of the center of DVs to the cell membrane (CM) is analyzed, DV density is found to decrease as the CM is approached. According to Monte Carlo simulations performed on the basis of the measured size distribution of DVs, this decay can be assigned to a "wall effect." Any cortical barrier, regardless of its function, seems to not impose a restriction to a random cortical DV packing pattern. The number of DVs closely approaching the CM (docked DVs) is estimated to be between 364 and 629 (average 496), i.e., 0.45 to 0.78 DVs/micron2 CM. Deprivation of Ca2+, priming by increasing [Ca2+]i, or depolarization by high [K+]e for 10 s (the effect of which was controlled electrophysiologically and predicted to change the number of readily releasable granules [RRGs]) does not significantly change the number of peripheral DVs. The reason may be that (a) structural docking implies only in part functional docking (capability of immediate release), and (b) exocytosis is rapidly followed by endocytosis and replenishment of the pool of docked DVs. Whereas the potential contribution of DVs to CM area increase by immediate release can be estimated at 19-33%, that of CVs is expected to be in the range of 5.6-8.0%.
TL;DR: In this article, the authors investigated whether triggering of caspase activity and/or activation of poly-(ADP-ribose) polymerase (PARP) played a role in cerebellar granule cell (CGC) apoptosis elicited by peroxynitrite (ONOO−) or NO donors.
Abstract: Excitotoxicity and excess generation of nitric oxide (NO) are believed to be fundamental mechanisms in many acute and chronic neurodegenerative disorders. Disturbance of Ca2+ homeostasis and protein nitration/nitrosylation are key features in such conditions. Recently, a family of proteases collectively known as caspases has been implicated as common executor of a variety of death signals. In addition, overactivation of poly-(ADP-ribose) polymerase (PARP) has been observed in neuronal excitotoxicity. We therefore designed this study to investigate whether triggering of caspase activity and/or activation of PARP played a role in cerebellar granule cell (CGC) apoptosis elicited by peroxynitrite (ONOO−) or NO donors. CGC from wild-type or PARP −/− mice were exposed to various nitric oxide donors. Caspase activation and its implications for membrane alterations, Ca2+ homeostasis, intracellular proteolysis, chromatin degradation, and cell death were investigated. CGC exposed to NO donors undergo apoptosis, which is mediated by excess synaptic release of excitotoxic mediators. This excitotoxic mechanism differs from direct NO toxicity in some other neuronal populations and does not involve PARP activation. Inhibition of caspases with different peptide substrates prevented cell death and the related features, including intracellular proteolysis, chromatin breakdown, and translocation of phosphatidylserine to the outer surface of the cell membrane. Increased Ca2+ influx following N-methyl-D-aspartate (NMDA) receptor (NMDA-R) activation was not inhibited by caspase inhibitors. In CGC, NO donors elicit apoptosis by a mechanism involving excitotoxic mediators, Ca2+ overload, and subsequent activation of caspases.
TL;DR: Hematotoxins such as alpha-amanitin may induce liver failure by an indirect mechanism involving sensitization of parenchymal cells toward endogenously produced TNF.
TL;DR: In this paper, a series of 5'-O-protected thymidine derivatives irradiated at 365 nm under identical conditions were tested for photolabile protection of nucleoside 5'-hydroxyls.
TL;DR: It is demonstrated that a cooperation of TNFR1 and TNFR2 is required for hepatotoxicity as mice deficient of either receptor were resistant against Con A and transmembrane TNF is sufficient to mediate hepatic damage.
Abstract: The significance of tumor necrosis factor receptor 1 (TNFR1) for TNF function in vivo is well documented, whereas the role of TNFR2 so far remains obscure. In a model of concanavalin A (Con A)-induced, CD4+ T cell-dependent experimental hepatitis in mice, in which TNF is a central mediator of apoptotic and necrotic liver damage, we now provide evidence for an essential in vivo function of TNFR2 in this pathophysiological process. We demonstrate that a cooperation of TNFR1 and TNFR2 is required for hepatotoxicity as mice deficient of either receptor were resistant against Con A. A significant role of TNFR2 for Con A-induced hepatitis is also shown by the enhanced sensitivity of transgenic mice overexpressing the human TNFR2. The ligand for cytotoxic signaling via both TNF receptors is the precursor of soluble TNF, i.e. transmembrane TNF. Indeed, transmembrane TNF is sufficient to mediate hepatic damage, as transgenic mice deficient in wild-type soluble TNF but expressing a mutated nonsecretable form of TNF developed inflammatory liver disease.
TL;DR: Sequence analysis of PIG cDNAs revealed similarities to genes encoding proteins involved in amino acid transport, thiamine biosynthesis, short-chain dehydrogenases, metallothioneins, cytochrome P-450 monooxygenases, and peptidyl-prolyl isomerases.
Abstract: Rust fungi are plant parasites that depend on living host tissue for growth. For invasion of leaves, dikaryotic urediospores differentiate germ tubes and infection structures that penetrate through stomata. Biotrophic growth occurs by intercellular mycelia that form haustoria within host cells. A cDNA library was constructed from haustoria isolated from broad bean leaves infected by Uromyces fabae. Differential screening revealed that a high proportion (19%) of the haustorial cDNAs are specifically expressed in planta but are not expressed, or are much weaker, in germlings or infection structures produced in vitro. A total of 31 different in planta-induced genes (PIGs) were identified. Some of the PIGs are highly expressed in haustoria. The PIGs are single or low copy number genes in the rust genome. A variety of developmentally regulated expression patterns of PIG mRNAs were observed. Sequence analysis of PIG cDNAs revealed similarities to genes encoding proteins involved in amino acid transport, thiamine biosynthesis, short-chain dehydrogenases, metallothioneins, cytochrome P-450 monooxygenases, and peptidyl-prolyl isomerases.
TL;DR: This article used a modified version of the Sternberg et al. (1978, 1980) prepared speech production paradigm to look for evidence of the generation of prosodic structure during the final stages of sentence production.
TL;DR: This new class of fluorophore yields promising probes for the study of protein/DNA interactions that are suitable for synthesis as phosphormidites and site-specific incorporation into oligonucleotides.
TL;DR: It is demonstrated that an hfq null mutant does not synthesize glycogen, is starvation and multiple stress sensitive, and exhibits strongly reduced expression of representative sigmaS-regulated genes, which are consistent with strongly reduced s SigmaS levels in the hfQ mutant.
Abstract: The hfq-encoded RNA-binding protein HF-I has long been known as a host factor for phage Qbeta RNA replication and has recently been shown to be essential for translation of rpoS, which encodes the sigmaS subunit of RNA polymerase. Here we demonstrate that an hfq null mutant does not synthesize glycogen, is starvation and multiple stress sensitive, and exhibits strongly reduced expression of representative sigmaS-regulated genes. These phenotypes are consistent with strongly reduced sigmaS levels in the hfq mutant. However, the analysis of global protein synthesis patterns on two-dimensional O'Farrell gels indicates that approximately 40% of the more than 30 proteins whose syntheses are altered in the hfq null mutant are not affected by an rpoS mutation. We conclude that HF-I is a global regulator involved in the regulation of expression of sigmaS and sigmaS-independent genes.
TL;DR: The in vitro differentiation of human peripheral blood monocytes to macrophages is characterized by a profound change in the PDE isoenzyme pattern, functionally reflected by an altered susceptibility towards selective PDE inhibitors under appropriate stimulating conditions.
Abstract: 1. During in vitro culture in 10% human AB serum, human peripheral blood monocytes acquire a macrophage-like phenotype. The underlying differentiation was characterized by increased activities of the macrophage marker enzymes unspecific esterase (NaF-insensitive form) and acid phosphatase, as well as by a down-regulation in surface CD14 expression. 2. In parallel, a dramatic change in the phosphodiesterase (PDE) profile became evident within a few days that strongly resembled that previously described for human alveolar macrophages. Whereas PDE1 and PDE3 activities were augmented, PDE4 activity, which represented the major cyclic AMP-hydrolysing activity of peripheral blood monocytes, rapidly declined. 3. Monocytes and monocyte-derived macrophages responded to lipopolysaccharide (LPS) with the release of tumour necrosis factor-alpha (TNF). In line with the change in CD14 expression, the EC50 value of LPS for induction of TNF release increased from approximately 0.1 ng ml-1 in peripheral blood monocytes to about 2 ng ml-1 in macrophages. 4. Both populations of cells were equally susceptible towards inhibition of TNF release by cyclic AMP elevating agents such as dibutyryl cyclic AMP, prostaglandin E2 (PGE2) or forskolin, which all led to a complete abrogation of TNF production in a concentration-dependent manner and which were more efficient than the glucocorticoid dexamethasone. 5. In monocytes, PDE4 selective inhibitors (rolipram, RP73401) suppressed TNF formation by 80%, whereas motapizone, a PDE3 selective compound, exerted a comparatively weak effect (10-15% inhibition). Combined use of PDE3 plus PDE4 inhibitors resulted in an additive effect and fully abrogated LPS-induced TNF release as did the mixed PDE3/4 inhibitor tolafentrine. 6. In monocyte-derived macrophages, neither PDE3- nor PDE4-selective drugs markedly affected TNF generation when used alone (< 15% inhibition), whereas in combination, they led to a maximal inhibition of TNF formation by about 40-50%. However, in the presence of PGE2 (10 nM), motapizone and rolipram or RP73401 were equally effective and blocked TNF release by 40%. Tolafentrine or motapizone in the presence of either PDE4 inhibitor, completely abrogated TNF formation in the presence of PGE2. Thus, an additional cyclic AMP trigger is necessary for PDE inhibitors to become effective in macrophages. 7. Finally, the putative regulatory role for PDE1 in the regulation of TNF production in macrophages was investigated. Zaprinast, at a concentration showing 80% inhibition of PDE1 activity (100 micromol l-1), did not influence TNF release. At higher concentrations (1 mmol l-1), zaprinast became effective, but this inhibition of TNF release can be attributed to a significant inhibitory action of this drug on PDE3 and PDE4 isoenzymes. 8. In summary, the in vitro differentiation of human peripheral blood monocytes to macrophages is characterized by a profound change in the PDE isoenzyme pattern. The change in the PDE4 to PDE3 ratio is functionally reflected by an altered susceptibility towards selective PDE inhibitors under appropriate stimulating conditions.
TL;DR: It is believed that sulfonate reduction is one aspect of a respiratory system transferring electrons from, e.g., formate to sulfite reductase via an electron transport system which presumably generates a proton gradient across the cell membrane.
Abstract: Organosulfonates are important natural and man-made compounds, but until recently (T. J. Lie, T. Pitta, E. R. Leadbetter, W. Godchaux III, and J. R. Leadbetter. Arch. Microbiol. 166:204-210, 1996), they were not believed to be dissimilated under anoxic conditions. We also chose to test whether alkane- and arenesulfonates could serve as electron sinks in respiratory metabolism. We generated 60 anoxic enrichment cultures in mineral salts medium which included several potential electron donors and a single organic sulfonate as an electron sink, and we used material from anaerobic digestors in communal sewage works as inocula. None of the four aromatic sulfonates, the three unsubstituted alkanesulfonates, or the N-sulfonate tested gave positive enrichment cultures requiring both the electron donor and electron sink for growth. Nine cultures utilizing the natural products taurine, cysteate, or isethionate were considered positive for growth, and all formed sulfide. Two clearly different pure cultures were examined. Putative Desulfovibrio sp. strain RZACYSA, with lactate as the electron donor, utilized sulfate, aminomethanesulfonate, taurine, isethionate, and cysteate, converting the latter to ammonia, acetate, and sulfide. Strain RZATAU was identified by 16S rDNA analysis as Bilophila wadsworthia. In the presence of, e.g., formate as the electron donor, it utilized, e.g., cysteate and isethionate and converted taurine quantitatively to cell material and products identified as ammonia, acetate, and sulfide. Sulfite and thiosulfate, but not sulfate, were utilized as electron sinks, as was nitrate, when lactate was provided as the electron donor and carbon source. A growth requirement for 1,4-naphthoquinone indicates a menaquinone electron carrier, and the presence of cytochrome c supports the presence of an electron transport chain. Pyruvate-dependent disappearance of taurine from cell extracts, as well as formation of alanine and release of ammonia and acetate, was detected. We suspected that sulfite is an intermediate, and we detected desulfoviridin (sulfite reductase). We thus believe that sulfonate reduction is one aspect of a respiratory system transferring electrons from, e.g., formate to sulfite reductase via an electron transport system which presumably generates a proton gradient across the cell membrane.