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  • 1
    Language: German
    Description: In this study, a urate oxidase mutant of Arabidopsis thaliana (uox) was characterized. Urate oxidase (UOX) is a peroxisomal enzyme involved in purine ring catabolism which catalyzes the oxidation of uric acid to 5-hydroxyisourate. UOX is expressed in late embryogenesis and during germination of the seedling, but also at later stages in leaves, roots and flower parts. In each of the mutants of purine ring degradation the substrate of the affected enzyme accumulates, but under standard growth conditions only uox shows a characteristic phenotype. Its germination rate is low and the seedlings are arrested in their growth on soil at an early stage. The seedlings fail to mobilize their lipid reserves and do not develop a primary root or green cotyledons. Therefore they need an external sugar supply to become autotrophic. As xdh (the xanthine dehydrogenase mutant) and xdh uox look normal, the lack of purine degradation itself or a structural function of UOX in peroxisomes can be ruled out as the cause of the uox phenotype. A colorimetric method to quantify uric acid in plant tissues was established and demonstrated its accumulation exclusively in all tissues of uox, but most prominently in developing and mature seeds. The assay showed a comparable accumulation of xanthine (the substrate of XDH) in seeds of xdh and xdh uox without causing any obvious phenotype. Obviously uric acid exerts a toxic effect during seed and seedling development whereas other oxopurines like xanthine do not. A metabolic profiling of seeds was performed. Gas chromatography coupled to mass spectrometry revealed a drastic elevation of uridine and sorbitol/galactitol in the seeds of uox. The latter indicates increased osmotic stress during the desiccation phase. Lipid analysis by ultraperformance liquid chromatography showed a significant increase of free fatty acids, but a decrease in the content of glycerophospholipids and short-chain triacylglycerides in uox in comparison to seeds of wild type and xdh uox. Transmission electron microscopy of cotyledons dissected from seeds revealed an altered morphology of protein storage vacuoles in uox with inclusions of unknown composition whereas xdh uox resembled the wild type. At the same time, with SDS-polyacrylamide gel electrophoresis, the content of storage proteins like cruciferin was found to be significantly lower in uox seeds. Confocal laser scanning microscopy of uox lines, in which GFP is targeted to peroxisomes, revealed a progressive loss of punctiform GFP signals in uox during late seed development, starting after the accumulation of uric acid. In mature embryos dissected from dry seeds of uox, most cotyledons contained none or only few functional peroxisomes. Hypocotyls were less affected, often displaying GFP signals in the apical part. The peroxisomal defect in cotyledons of uox was confirmed by cytochemical staining for catalase with diamino benzidine (DAB), which demonstrated numerous DAB-signals in semi thin sections of cotyledons of wild type and xdh uox but none in preparations of uox. In summary, the results of this study indicate that the accumulation of uric acid during seed development in uox is the likely cause of the loss of peroxisomal function in cotyledons and hypocotyls, which then leads to the germination defect in seeds of uox and the failure of uox seedlings to establish.
    Keywords: Ddc:500 ; 500 Natural Sciences And Mathematics ; 500 Naturwissenschaften Und Mathematik ; 570 Life Sciences ; Ddc:570 ; 570 Biowissenschaften; Biologie ; 572 Biochemistry ; 572 Biochemie ; Ddc:572 ; Urate Oxidase ; Arabidopsis Thaliana ; Uric Acid ; Peroxisome ; Germination Defect
    Source: Freie Universitat Berlin
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  • 2
    Language: English
    In: PLoS ONE, 01 January 2013, Vol.8(12), p.e82755
    Description: Autoimmune pancreatitis (AIP) is defined by characteristic lymphoplasmacytic infiltrate, ductal strictures and a pancreatic enlargement or mass that can mimic pancreatic cancer (PaCa). The distinction between this benign disease and pancreatic cancer can be challenging. However, an accurate...
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 3
    Language: English
    In: BIO-PROTOCOL, 2015, Vol.5(13)
    ISSN: 2331-8325
    Source: CrossRef
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  • 4
    Language: English
    In: The Plant cell, July 2014, Vol.26(7), pp.3090-100
    Description: Purine nucleotides can be fully catabolized by plants to recycle nutrients. We have isolated a urate oxidase (uox) mutant of Arabidopsis thaliana that accumulates uric acid in all tissues, especially in the developing embryo. The mutant displays a reduced germination rate and is unable to establish autotrophic growth due to severe inhibition of cotyledon development and nutrient mobilization from the lipid reserves in the cotyledons. The uox mutant phenotype is suppressed in a xanthine dehydrogenase (xdh) uox double mutant, demonstrating that the underlying cause is not the defective purine base catabolism, or the lack of UOX per se, but the elevated uric acid concentration in the embryo. Remarkably, xanthine accumulates to similar levels in the xdh mutant without toxicity. This is paralleled in humans, where hyperuricemia is associated with many diseases whereas xanthinuria is asymptomatic. Searching for the molecular cause of uric acid toxicity, we discovered a local defect of peroxisomes (glyoxysomes) mostly confined to the cotyledons of the mature embryos, which resulted in the accumulation of free fatty acids in dry seeds. The peroxisomal defect explains the developmental phenotypes of the uox mutant, drawing a novel link between uric acid and peroxisome function, which may be relevant beyond plants.
    Keywords: Arabidopsis -- Enzymology ; Peroxisomes -- Metabolism ; Urate Oxidase -- Metabolism ; Uric Acid -- Metabolism
    ISSN: 10404651
    E-ISSN: 1532-298X
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  • 5
    In: Pancreas, 2016, Vol.45(9), pp.1309-1319
    Description: OBJECTIVES: The lack of specific biochemical markers is a major drawback for the diagnosis of autoimmune pancreatitis (AIP). The aims were to characterize the autoantibody profiles in AIP and pancreatic ductal adenocarcinoma (PDAC) and to identify circulating autoantibodies that could be diagnostic markers differentiating PDAC and the AIP subtypes. METHODS: Tissue lysates obtained from the resected pancreas of patients with AIP and patients with PDAC were separated by 2-dimensional polyacrylamide gel electrophoresis subsequently immunoblotted with autologous sera. The immunoreactive spots were subjected to nanoscale liquid chromatography–electrospray ionization tandem mass spectrometry to identify serum autoantibodies to tissue-derived autoantigens associated with AIP and PDAC. Autoantibody concentrations for selected autoantigens were assessed by enzyme-linked immunosorbent assays. RESULTS: A total of 115 immunoreactive spots were identified by 2-dimensional polyacrylamide gel electrophoresis/immunobloting. Nanoscale liquid chromatography–electrospray ionization tandem mass spectrometry–based analysis revealed 68 autoantigens in AIP, 26 in PDAC, and 21 present in both diseases. Assessment of 13 selected AIP autoantibody serum levels revealed that 7 of them had significantly higher titers in AIP versus PDAC. IgG-directed against transaldolase could significantly differentiate between the 2 AIP subtypes. CONCLUSIONS: The novel panel of AIP autoantibodies is promising to supplement the predictive tests for AIP of the currently known autoantigens and represent a basis for a combined blood test to differentiate AIP from PDAC in the future.
    Keywords: Carcinoma, Pancreatic Ductal ; Pancreatic Neoplasms ; Pancreatitis;
    ISSN: 0885-3177
    E-ISSN: 15364828
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  • 6
    Language: English
    Description: Techn. University, Diss., 2006--Darmstadt.
    Keywords: Pipeline-Verarbeitung. Computerarithmetik. Kryptologie. Monte-Carlo-Simulation. Hochgeschwindigkeit. Zeitverhalten. Vlsi. Datenpfad. Cmos-Schaltung. Pipeline-Rechner.
    Source: Networked Digital Library of Theses and Dissertations
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  • 7
    Language: English
    Description: Darmstadt, Techn. Univ., Diss., 2006 Dateien im PDF-Format
    Source: Networked Digital Library of Theses and Dissertations
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  • 8
    Dissertation
    Dissertation
    [S.l.] : [s.n.],
    Description: Darmstadt, Techn. Univ., Diss., 2006. Dateien im PDF-Format.
    Source: Networked Digital Library of Theses and Dissertations
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  • 9
    Language: English
    In: Journal of Shoulder and Elbow Surgery
    Description: Current ulnar collateral ligament (UCL) reconstruction techniques are substantially less stiff and demonstrate lower load to failure compared with the native UCL. UCL repair with the addition of an internal brace has demonstrated superior biomechanical performance compared with docking UCL reconstruction, but internal bracing has not yet been used in UCL reconstruction. To evaluate the time-zero biomechanical performance of a UCL docking technique reconstruction with and without an internal brace compared with native UCL properties. Twelve matched pairs of cadaveric elbows were dissected and fixed at 90° for biomechanical testing. A cyclic valgus torque protocol was used to test the anterior band of the UCL in native specimens. After native specimens were failed, palmaris grafts were used for a docking reconstruction with or without internal brace and were subjected to the same valgus torque test protocol. Torsional stiffness, ultimate failure torque, and ulnohumeral gapping were determined. Stiffness in UCL reconstructions using a standard docking technique (3.0 ± 0.4 N m/deg) were significantly less stiff ( .001) than native UCL (4.0 ± 0.8 N m/deg), whereas reconstructions using an internal brace (3.6 ± 0.6 N m/deg) were not different ( = .120) compared with native. Ultimate failure torque for standard docking (18.3 ± 4.1 N m) was significantly lower ( .001) than native UCL (36.9 ± 10.1 N m), whereas the internal brace samples (35.3 ± 9.8 N m) were not different ( .772) than native. UCL reconstruction with an internal brace augmentation provides superior stiffness and time-zero failure strength when compared with the standard docking technique.
    Keywords: Elbow ; Ucl Reconstruction ; Internal Brace
    ISSN: 1058-2746
    E-ISSN: 1532-6500
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  • 10
    Language: English
    In: American Journal of Preventive Medicine, 2006, Vol.30(2), pp.S67-S76
    Description: Racial disparities exist in prostate cancer incidence. An important contributor to these disparities may be socioeconomic status. Virginia Cancer Registry data, 1990–1999 (37,373 cases) were geocoded to the Census tract and county level. The annualized, age-adjusted incidence rates for African Americans and whites were calculated, and crude and smoothed maps of these rates were produced. Statistical tests for clustering of cases were conducted. Prostate cancer incidence was statistically modeled as a function of area-based measures of poverty, median household income, education, rural status, ratio of physicians to population in each county, percentage of men in each county obtaining prostate cancer screening with the prostate-specific antigen (PSA) test, and percent of households headed by females. Prostate cancer incidence was elevated in the eastern and central portions of the state. Statistical tests for clustering were highly significant (Tango’s test, 〈0.008; spatial scan statistic, 〈0.001). Poverty and lower education were associated with a decreased incidence among whites but not African Americans. Median household income and urban status were positively associated with incidence for both populations. Among whites, increased percent of female heads of households and ratio of physicians per population were associated with increased incidence. Associations between predictor variables and prostate cancer incidence were seen only in the census tract level analyses. Overall, the findings support the argument that area measures of poverty and education do not explain the increased incidence of prostate cancer among African Americans. Other factors, such as dietary practices, may help explain racial disparities in prostate cancer incidence. Because of the large differences between tract and county level results, the time and expense of obtaining data geocoded to the tract level seems worthwhile.
    Keywords: Medicine ; Public Health
    ISSN: 0749-3797
    E-ISSN: 1873-2607
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