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51.
Tsikas D Thum T Becker T Pham VV Chobanyan K Mitschke A Beckmann B Gutzki FM Bauersachs J Stichtenoth DO 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2007,851(1-2):229-239
Dimethylamine [DMA, (CH(3))(2)NH)] is abundantly present in human urine. Main sources of urinary DMA have been reported to include trimethylamine N-oxide, a common food component, and asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide (NO) synthesis. ADMA is excreted in the urine in part unmetabolized and in part after hydrolysis to DMA by dimethylarginine dimethylaminohydrolase (DDAH). Here we describe a GC-MS method for the accurate and rapid quantification of DMA in human urine. The method involves use of (CD(3))(2)NH as internal standard, simultaneous derivatization with pentafluorobenzoyl chloride and extraction in toluene, and selected-ion monitoring of m/z 239 for DMA and m/z 245 for (CD(3))(2)NH in the electron ionization mode. GC-MS analysis of urine samples from 10 healthy volunteers revealed a DMA concentration of 264+/-173 microM equivalent to 10.1+/-1.64 micromol/mmol creatinine. GC-tandem MS analysis of the same urine samples revealed an ADMA concentration of 27.3+/-15.3 microM corresponding to 1.35+/-1.2 micromol/mmol creatinine. In these volunteers, a positive correlation (R=0.83919, P=0.0024) was found between urinary DMA and ADMA, with the DMA/ADMA molar ratio being 10.8+/-6.2. Elevated excretion rates of DMA (52.9+/-18.5 micromol/mmol creatinine) and ADMA (3.85+/-1.65 micromol/mmol creatinine) were found by the method in 49 patients suffering from coronary artery disease, with the DMA/ADMA molar ratio also being elevated (16.8+/-12.8). In 12 patients suffering from end-stage liver disease, excretion rates of DMA (47.8+/-19.7 micromol/mmol creatinine) and ADMA (5.6+/-1.5 micromol/mmol creatinine) were found to be elevated, with the DMA/ADMA molar ratio (9.17+/-4.2) being insignificantly lower (P=0.46). Between urinary DMA and ADMA there was a positive correlation (R=0.6655, P<0.0001) in coronary artery disease, but no correlation (R=0.27339) was found in end-stage liver disease. 相似文献
52.
Increased production of bacteriocin ST4SA byEnterococcus mundtii ST4SA in modified corn steep liquor
Johan C. J. Coetzee Svetoslav D. Todorov Johann F. Görgens Leon M. T. Dicks 《Annals of microbiology》2007,57(4):617-622
Enterococcus mundtii ST4SA produces a broad-spectrum bacteriocin (bacST4SA), active against Gram-positive and Gramnegative bacteria. Growth in corn steep liquor (CSL) with a sugar content of 5.0 and 10.0 g/l yielded bacST4SA levels of 12800 AU/ml. A four-fold increase in bacST4SA production (51200 AU/ml) was recorded in CSL with a sugar content of 7.5 g/l supplemented with 6.5 g/l yeast extract (CSL-YE). Poor growth and low levels of bacST4SA production were observed when cells were grown in CSL-YE controlled at pH 5.5. Fermentation at pH 7.5 yielded 25600 AU/ml after 6 h, but the activity levels decreased to approximately 1000 AU/ml during the next 6 h. Adjustment of the culture pH from 6.5 to 5.5 after 6 h of fermentation extended bacST4SA activity (51200 AU/ml) over 8 h. Activity then decreased to 25600 AU/ml and was maintained this level for 10 h. Optimal levels of bacST4SA production (102400 AU/ml) were obtained after 6 h of fermentation in CSL-YE supplemented with 7.5 g/l glucose at the start of the fermentation. This level of production was maintained by changing the culture pH from 6.5 after 6 h of fermentation to pH 5.5. This study proved that bacST4SA could be produced at high levels in an inexpensive industrial medium byE. mundtii ST4SA. 相似文献
53.
A conceptual framework is developed and used for improving the livelihood of Sub-Saharan communities faced with multiple stresses
resulting from adverse environments, vector-transmitted diseases, and limited food. Ecosocial systems are the units for management.
The accumulation of ecological, economic, and social capital is the objective of management, the reduction of maintenance
costs is the key strategy, and technologies must satisfy ecological, economic, and social criteria. Interacting social system
components are communities, facilitators, scientists, and political as well as administrative organizations. An adaptive approach
to management allows flexibility in human and financial resource allocation and results in changes in knowledge and efficacy
of management operations. The implementation strategy at two sites in Ethiopia relies on a two-stage procedure. In Stage 1,
human and cattle health management set the conditions for development. In Stage 2, the ecosocial system is kept on a trajectory
to enhanced ecological, economic, and social capital. In each stage, the assignment of responsibilities leads to four implementation
phases. In Stage 1, successful precision targeting of tsetse and drug-based Trypanosoma spp. control increased the economic and social capital at the Luke site in southwestern Ethiopia but threatened the ecological
capital because of overstocking and land degradation. In Stage 2, a women’s group living in the outskirts of Addis Ababa (Ethiopia)
transformed barren land into a horticultural enterprise to enhance ecosystem service provision, including production of horticultural
goods, and increase soil fertility expressed by nutrients and water availability. This article reviews concepts on human livelihood
improvement in Sub-Saharan Africa and identifies principles that became important during project execution. 相似文献
54.
Berger Andreas Valant-Vetschera Karin Schinnerl Johann Brecker Lothar 《Phytochemistry Reviews》2022,21(3):915-939
Phytochemistry Reviews - The species-rich genus Palicourea (Rubiaceae: Palicoureeae) is source of an intriguing diversity of alkaloids derived from tryptamine and its precursor tryptophan. So far... 相似文献
55.
Berger Andreas Valant-Vetschera Karin Schinnerl Johann Brecker Lothar 《Phytochemistry Reviews》2022,21(3):941-986
Phytochemistry Reviews - Tribes Palicoureeae and Psychotrieae (Rubiaceae, Gentianales) are complex and speciose sister groups with a pantropical distribution. Since the initial studies on... 相似文献
56.
Johann H van Niekerk 《Ostrich》2019,90(1):37-40
This study describes the relationship between Helmeted Guineafowl Numida meleagris and invasive alien trees on livestock and maize farms south-east of Johannesburg, Gauteng province, South Africa. The dependence of the birds on alien trees affects strategies for the removal of these trees. During June to December 2014, Helmeted Guineafowl were recorded weekly on maps along a 42 km transect. Since Helmeted Guineafowl live in cohesive social groups of 15–20 birds, they roost communally in one or two trees during winter rather than spreading across an entire tree grove. The distribution of alien trees across the landscape in patches has enabled Helmeted Guineafowl flocks to reach new feeding patches near to roosting trees, as old feeding patches are depleted. One Helmeted Guineafowl flock of 15–20 birds requires ~0.09 ha covered with mature alien trees for roosting. Suggestions are presented relating to the reduction of alien trees in compliance with the Conservation of Agricultural Resources Act 43 of 1983 and conservation of Helmeted Guineafowl. 相似文献
57.
Carpentier Alice S. Berthe Cécile Ender Isabel Jaine Fabrice R. A. Mourier Johann Stevens Guy De Rosemont Moeava Clua Eric 《Coral reefs (Online)》2019,38(6):1353-1353
Coral Reefs - This erratum has been initiated as many corrections which were submitted during proofing were overlooked by vendor. 相似文献
58.
59.
Yihang Li Maria F. Pazyra-Murphy Daina Avizonis Mariana de S Tavares Russo Sophia Tang Chiung-Ya Chen Yi-Ping Hsueh Johann S. Bergholz Tao Jiang Jean J. Zhao Jian Zhu Kwang Woo Ko Jeffrey Milbrandt Aaron DiAntonio Rosalind A. Segal 《The Journal of cell biology》2022,221(2)
Cancer patients frequently develop chemotherapy-induced peripheral neuropathy (CIPN), a painful and long-lasting disorder with profound somatosensory deficits. There are no effective therapies to prevent or treat this disorder. Pathologically, CIPN is characterized by a “dying-back” axonopathy that begins at intra-epidermal nerve terminals of sensory neurons and progresses in a retrograde fashion. Calcium dysregulation constitutes a critical event in CIPN, but it is not known how chemotherapies such as paclitaxel alter intra-axonal calcium and cause degeneration. Here, we demonstrate that paclitaxel triggers Sarm1-dependent cADPR production in distal axons, promoting intra-axonal calcium flux from both intracellular and extracellular calcium stores. Genetic or pharmacologic antagonists of cADPR signaling prevent paclitaxel-induced axon degeneration and allodynia symptoms, without mitigating the anti-neoplastic efficacy of paclitaxel. Our data demonstrate that cADPR is a calcium-modulating factor that promotes paclitaxel-induced axon degeneration and suggest that targeting cADPR signaling provides a potential therapeutic approach for treating paclitaxel-induced peripheral neuropathy (PIPN). 相似文献
60.
Chang-An Yu Hua Tian Li Zhang Kai-Ping Deng Sudha K. Shenoy Linda Yu Di Xia Hoeon Kim Johann Deisenhofer 《Journal of bioenergetics and biomembranes》1999,31(3):191-200
The mitochondrial cytochrome bc
1 complex is a multifunctional membrane protein complex. Itcatalyzes electron transfer, proton translocation, peptide processing, and superoxide generation.Crystal structure data at 2.9 Å resolution not only establishes the location of the redox centersand inhibitor binding sites, but also suggests a movement of the head domain of the iron–sulfurprotein (ISP) during bc
1 catalysis and inhibition of peptide-processing activity during complexmaturation. The functional importance of the movement of extramembrane (head) domain ofISP in the bc
1 complex is confirmed by analysis of the Rhodobacter sphaeroides bc
1 complexmutants with increased rigidity in the ISP neck and by the determination of rate constants foracid/base-induced intramolecular electron transfer between [2Fe–2S] and heme c
1 in nativeand inhibitor-loaded beef complexes. The peptide-processing activity is activated in bovineheart mitochondrial bc
1 complex by nonionic detergent at concentrations that inactivate electrontransfer activity. This peptide-processing activity is shown to be associated with subunits Iand II by cloning, overexpression and in vitro reconstitution. The superoxide-generation siteof the cytochrome bc
1 complex is located at reduced b
L and Q–. The reaction is membranepotential-, and cytochrome c-dependent. 相似文献