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81.
H Langen T Epprecht M Linden T Hehlgans B Gutte H R Buser 《European journal of biochemistry》1989,182(3):727-735
Heme compounds, in combination with a reducing agent and oxygen, can express various activities of cytochrome P-450 enzymes. In the present study it was found that a mixture of hemin and excess cysteine was able to degrade the insecticide DDT partially. The major products were three water-soluble, non-toxic conjugates of DDT metabolites with cysteine which had lost two or three of the five chlorine atoms of DDT per molecule and whose structures were elucidated by gas chromatography/mass spectrometry. In 0.05 M NH4HCO3, pH 7.7/ethanol (5:6, by vol.), the degradation reaction catalyzed by the hemin-cysteine model system was at least 8 x 10(4) times faster than the uncatalyzed reaction. In the presence of a designed 24-residues polypeptide or beta-casein, two DDT-binding proteins, an additional fourfold increase in the rate of DDT degradation was observed. Although the concentrations of DDT and cysteine occurring in an organism would be expected to be lower than those in the experiments described, the formation of water-soluble conjugates of DDT metabolites with cysteine (and other amino acids) could also play a role in metabolism and excretion of DDT in vivo. 相似文献
82.
Chanchal Sur Chowdhury Stavros Giaglis Ulrich A Walker Andreas Buser Sinuhe Hahn Paul Hasler 《Arthritis research & therapy》2014,16(3):R122
Introduction
Neutrophil extracellular traps (NETs) have recently been implicated in a number of autoimmune conditions, including rheumatoid arthritis (RA). We examined the underlying signaling pathways triggering enhanced NETosis in RA and ascertained whether the products of NETosis had diagnostic implications or usefulness.Methods
Neutrophils were isolated from RA patients with active disease and from controls. Spontaneous NET formation from RA and control neutrophils was assessed in vitro with microscopy and enzyme-linked immunosorbent assay (ELISA) for NETosis-derived products. The analysis of the signal-transduction cascade included reactive oxygen species (ROS) production, myeloperoxidase (MPO), neutrophil elastase (NE), peptidyl arginine deiminase 4 (PAD4), and citrullinated histone 3 (citH3). NET formation was studied in response to serum and synovial fluid and immunoglobulin G (IgG) depleted and reconstituted serum. Serum was analyzed for NETosis-derived products, for which receiver operator characteristic (ROC) curves were calculated.Results
Neutrophils from RA cases exhibited increased spontaneous NET formation in vitro, associated with elevated ROS production, enhanced NE and MPO expression, nuclear translocation of PAD4, PAD4-mediated citrullination of H3, and altered nuclear morphology. NET formation in both anti-citrullinated peptide antibody (ACPA)-positive and -negative RA was abolished by IgG depletion, but restored only with ACPA-positive IgG. NETosis-derived products in RA serum demonstrated diagnostic potential, the ROC area under the curve for cell-free nucleosomes being >97%, with a sensitivity of 91% and a specificity of 92%. No significant difference was observed between ACPA-positive and -negative cases.Conclusions
Signaling elements associated with the extrusion of NETs are significantly enhanced to promote NETosis in RA compared with healthy controls. NETosis depended on the presence of ACPA in ACPA-positive RA serum. The quantitation of NETosis-derived products, such as cell-free nucleosomes in serum, may be a useful complementary tool to discriminate between healthy controls and RA cases. 相似文献83.
R Quintero‐Torres HA Castillo‐Matadamas Jeff F Young RM Bermúdez Cruz 《Luminescence》2014,29(5):440-444
Relaxation dynamics is universal in science and engineering; its study serves to parameterize a system's response and to help identify a microscopic model of the processes involved. When measured data for a phenomenon cannot be fitted using one exponential, the choice of an alternative function to describe the decay becomes nontrivial. Here, we contrast two different, but fundamentally related approaches to fitting nontrivial decay curves; exponential decomposition and the gamma probability density function. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
84.
Sharma P Raina V Kumari R Malhotra S Dogra C Kumari H Kohler HP Buser HR Holliger C Lal R 《Applied and environmental microbiology》2006,72(9):5720-5727
Incubation of resting cells of Sphingobium indicum B90A, Sphingobium japonicum UT26, and Sphingobium francense Sp+ showed that they were able to transform beta- and delta-hexachlorocyclohexane (beta- and delta-HCH, respectively), the most recalcitrant hexachlorocyclohexane isomers, to pentachlorocyclohexanols, but only resting cells of strain B90A could further transform the pentachlorocyclohexanol intermediates to the corresponding tetrachlorocyclohexanediols. Moreover, experiments with resting cells of Escherichia coli expressing the LinB proteins of strains B90A, UT26, and Sp+ indicated that LinB was responsible for these transformations. Purified LinB proteins from all three strains also effected the formation of the respective pentachlorocyclohexanols. Although the three LinB enzymes differ only marginally with respect to amino acid sequence, they showed interesting differences with respect to substrate specificity. When LinB from strain B90A was incubated with beta- and delta-HCH, the pentachlorocyclohexanol products were further transformed and eventually disappeared from the incubation mixtures. In contrast, the LinB proteins from strains UT26 and Sp+ could not catalyze transformation of the pentachlorocyclohexanols, and these products accumulated in the incubation mixture. A mutant of strain Sp+ lacking linA and linB did not degrade any of the HCH isomers, including beta-HCH, and complementation of this mutant by linB from strain B90A restored the ability to degrade beta- and delta-HCH. 相似文献
85.
Buser P 《Comptes rendus biologies》2006,329(5-6):398-405
This paper analyses an interesting story, that of the physiologist Ivan Petrovitch Pavlov. While investigating the causes of salivary secretions in the waking, behaving dog, he discovered a class of causes that he called psychic, since they were associated with perceiving a visual, acoustic or other signal, delivered before food that normally created salivation. A temporary relationship was therefore established, between the secretory command and the cerebral site associated with an initially neutral stimulus that had become a signal. This gave rise to the "conditional reflex". Pavlov was probably not the first who had observed this kind of association, but he very skillfully exploited these data to create a coherent conceptual system. In 23 "lectures", he very precisely summarized his views and retraced the fundamental issues explaining the main features of the purely physiological cerebral command of behaviour. The Pavlovian system necessarily became, in the particular environment of the soviet regime, a kind of credo on physical-mental relationships based upon a generalized reflexology, not allowing any deviation, nor any dissidence, nor any concession to subjectivity. The notion of conditional reflex has indeed resisted to time, but number of subtleties of the Pavlovian thinking and many phenomena that he described now seem forgotten and to have lost much of their heuristic value. Most of the recent theories of learning have only rarely followed Pavlov's line, to concentrate on more complex learning modalities. 相似文献
86.
Narayan P Subramaniyam Outi RM Väisänen Katrina E Wendel Jaakko AV Malmivuo 《Nonlinear biomedical physics》2010,4(Z1):S4
Background
The electroencephalography (EEG) is an attractive and a simple technique to measure the brain activity. It is attractive due its excellent temporal resolution and simple due to its non-invasiveness and sensor design. However, the spatial resolution of EEG is reduced due to the low conducting skull. In this paper, we compute the potential distribution over the closed surface covering the brain (cortex) from the EEG scalp potential. We compare two methods – L-curve and generalised cross validation (GCV) used to obtain the regularisation parameter and also investigate the feasibility in applying such techniques to N170 component of the visually evoked potential (VEP) data.Methods
Using the image data set of the visible human man (VHM), a finite difference method (FDM) model of the head was constructed. The EEG dataset (256-channel) used was the N170 component of the VEP. A forward transfer matrix relating the cortical potential to the scalp potential was obtained. Using Tikhonov regularisation, the potential distribution over the cortex was obtained.Results
The cortical potential distribution for three subjects was solved using both L-curve and GCV method. A total of 18 cortical potential distributions were obtained (3 subjects with three stimuli each – fearful face, neutral face, control objects).Conclusions
The GCV method is a more robust method compared to L-curve to find the optimal regularisation parameter. Cortical potential imaging is a reliable method to obtain the potential distribution over cortex for VEP data.87.
Bacillus pumilus was isolated from surface-sterilized tissues of the medicinal plant Ocimum sanctum. Scanning electron microscopic (SEM) imaging confirmed the presence of a rod shaped bacterium within the plant tissues. The bacterium was identified as B. pumilus by biochemical analyses and 16S rRNA gene sequencing. In vitro analyses indicate that the isolated strain of B. pumilus was endowed with multiple plant growth promotion (PGP) traits such as phosphate solubilization and the production of indole acetic acid (IAA), siderophore and hydrogen cyanide (HCN). Phosphate solubilization (37.3 μg ml?1) and IAA production (36.7 μg ml?1) by the isolate was found to reach a maximum after 60 h of incubation. Siderophore mediated iron sequestration by B. pumilus may confer a competitive advantage to the host with respect to pathogen inhibition. Siderophore produced by the isolate was found to be of a trihydroxamate type with hexadentate nature. The B. pumilus isolate also exhibited cellulolytic, proteolytic and chitinolytic activity. Cell free supernatant, culture filtrates of the isolate were found to suppress the growth of fungal phytopathogens. The culture filtrate retained its antifungal activity even after exposure to heat. In addition to PGP, the isolate exhibited probiotic properties such as acid tolerance (pH2), bile salt tolerance (2 %), auto-aggregation, antibiotic resistance and the absence of haemolytic activity. These finding suggest the possibility of utilizing this endophytic strain of B. pumilus as a bioinoculant to enhance plant growth and also as a probiotic. 相似文献
88.
RM Christie 《Biotechnic & histochemistry》2013,88(2):51-56
Although the color of indigo is strongly dependent on its environment, it is blue in most commonly encountered situations. Indigo's absorption at such long wavelengths for such a small molecule is unique, and I provide here an overview of the concepts advanced to account for this feature. A traditional valence–bond approach may be used to provide a reasonable qualitative explanation. A more rigorous, quantitative explanation is provided by molecular orbital methods of varying degrees of sophistication and several explanations have been proposed based on these models. Commonly, it is suggested that the important structural unit in determining color is based on the cross-conjugated “H-chromophore” concept. A second closely related explanation describes it as two symmetrically coupled merocyanine chains. Another proposal suggests that the basic chromophore may be interpreted as the aza analogue of two coupled anti aromatic-cyclopentadienyl ions. PiSYSTEM, a commercially available quantum mechanics program, has been used to provide a successful quantitative account of the colors of indigo and indirubin, a red isomer. 相似文献
89.
Bergman JM Abrams MT Davide JP Greenberg IB Robinson RG Buser CA Huber HE Koblan KS Kohl NE Lobell RB Graham SL Hartman GD Williams TM Dinsmore CJ 《Bioorganic & medicinal chemistry letters》2001,11(11):1411-1415
A series of aryloxy substituted piperazinones with dual farnesyltransferase/geranylgeranyltransferase-I inhibitory activity was prepared. These compounds were found to have potent inhibitory activity in vitro and are promising agents for the inhibition of Ki-Ras signaling. 相似文献
90.
Andre Loboda Michael V Nebozhyn James W Watters Carolyne A Buser Peter Martin Shaw Pearl S Huang Laura Van’t Veer Rob AEM Tollenaar David B Jackson Deepak Agrawal Hongyue Dai Timothy J Yeatman 《BMC medical genomics》2011,4(1):1-10