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    PGC1alpha drives NAD biosynthesis linking oxidative metabolism to renal protection (2016)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2016-03-17
    Description: The energetic burden of continuously concentrating solutes against gradients along the tubule may render the kidney especially vulnerable to ischaemia. Acute kidney injury (AKI) affects 3% of all hospitalized patients. Here we show that the mitochondrial biogenesis regulator, PGC1alpha, is a pivotal determinant of renal recovery from injury by regulating nicotinamide adenine dinucleotide (NAD) biosynthesis. Following renal ischaemia, Pgc1alpha(-/-) (also known as Ppargc1a(-/-)) mice develop local deficiency of the NAD precursor niacinamide (NAM, also known as nicotinamide), marked fat accumulation, and failure to re-establish normal function. Notably, exogenous NAM improves local NAD levels, fat accumulation, and renal function in post-ischaemic Pgc1alpha(-/-) mice. Inducible tubular transgenic mice (iNephPGC1alpha) recapitulate the effects of NAM supplementation, including more local NAD and less fat accumulation with better renal function after ischaemia. PGC1alpha coordinately upregulates the enzymes that synthesize NAD de novo from amino acids whereas PGC1alpha deficiency or AKI attenuates the de novo pathway. NAM enhances NAD via the enzyme NAMPT and augments production of the fat breakdown product beta-hydroxybutyrate, leading to increased production of prostaglandin PGE2 (ref. 5), a secreted autacoid that maintains renal function. NAM treatment reverses established ischaemic AKI and also prevented AKI in an unrelated toxic model. Inhibition of beta-hydroxybutyrate signalling or prostaglandin production similarly abolishes PGC1alpha-dependent renoprotection. Given the importance of mitochondrial health in ageing and the function of metabolically active organs, the results implicate NAM and NAD as key effectors for achieving PGC1alpha-dependent stress resistance.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tran, Mei T -- Zsengeller, Zsuzsanna K -- Berg, Anders H -- Khankin, Eliyahu V -- Bhasin, Manoj K -- Kim, Wondong -- Clish, Clary B -- Stillman, Isaac E -- Karumanchi, S Ananth -- Rhee, Eugene P -- Parikh, Samir M -- K08-DK090142/DK/NIDDK NIH HHS/ -- K08-DK101560/DK/NIDDK NIH HHS/ -- P30-DK079337/DK/NIDDK NIH HHS/ -- R01 DK095072/DK/NIDDK NIH HHS/ -- R01-DK095072/DK/NIDDK NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2016 Mar 24;531(7595):528-32. doi: 10.1038/nature17184. Epub 2016 Mar 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA. ; Center for Vascular Biology Research, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA. ; Division of Clinical Chemistry, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA. ; Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA. ; Bioinformatics and Systems Biology Core, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA. ; Nephrology and Endocrine Divisions, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA. ; Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02139, USA. ; Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26982719" target="_blank"〉PubMed〈/a〉
    Keywords: 3-Hydroxybutyric Acid/metabolism ; Acute Kidney Injury/drug therapy/*metabolism ; Adipose Tissue/drug effects/metabolism ; Amino Acids/metabolism ; Animals ; Cytokines/metabolism ; Dinoprostone/biosynthesis/metabolism ; Humans ; Ischemia/drug therapy/metabolism ; Kidney/drug effects/*metabolism/physiology/physiopathology ; Male ; Mice ; Mice, Inbred C57BL ; Mitochondria/metabolism ; NAD/*biosynthesis ; Niacinamide/deficiency/pharmacology/therapeutic use ; Nicotinamide Phosphoribosyltransferase/metabolism ; Oxidation-Reduction ; Signal Transduction/drug effects ; Stress, Physiological ; Transcription Factors/deficiency/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamics and kinetics of the interaction of copper (II) ions with native DNA (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 625-661 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on equilibrium binding studies, as well as on kinetic investigations, two types of interactions of Cu2+ ions with native DNA at low ionic strength could be characterized, namely, a nondenaturing and a denaturing complex formation. During a fast nondenaturing complex formation at low relative ligand concentrations and at low temperatures, different binding sites at the DNA bases become occupied by the metal ions. This type of interaction includes chelate formation of Cu2+ ions with atoms N(7) of purine bases and the oxygens of the corresponding phosphate groups, chelation between atoms N(7) and O of C(6) of the guanine bases, as well as the formation of specific intestrand crosslink complexes at adjacent G°C pairs of the sequence dGpC. CD spectra of the resulting nondenatured complex (DNA-Cu2+)nat may be interpreted in terms of a conformational change of DNA from the B-form to a C-like form on ligand binding. A slow cooperative denaturing complex formation occurs at increased copper concentrations and/or at increased temperatures. The uv absorption and CD spectra of the resulting complex, (DNA-Cu2+)denat, indicate DNA denaturation during this type of interaction. Such a conclusion is confirmed by microcalorimetric measurements, which show that the reaction consumes nearly the same amount of heat as acid denaturation of DNA.From these and the kinetic results, the following mechanism for the denaturing action of the ligands is suggested: binding of Cu2+ ions to atoms N(3) of the cytosine bases takes place when the cytosines come to the outside of the double helix as a result of statistical fluctuations. After the completion of the binding process, the bases cannot return to their initial positions, and thus local denaturation at the G·C pairs is brought about. The probability of the necessary fluctuations occurring is increased by chelation of Cu2+ ions between atoms N(7) and O of C(6) of the guanine bases during nondenaturing complex formation, which loosens one of the hydrogen bonds within the G·C pairs, as well as by raising the temperature. The implications of the new binding model, which comprises both the sequence-specific interstand crosslinks and the described mechanism of denaturing complex formation, are discussed and some predictions are made. The model is also used to explain the different renaturation properties of the denatured complexes of Cu2+, Cd2+, and Zn2+ ions with DNA.In temperature-jump experiments with the nondenatured complex (DNA-Cu2+)nat, a specific kinetic effect is observed, namely, the appearance of a lag in the response to the perturbation. The resulting sigmoidal shape of the kinetic curves is considered to be a consequence of the necessity of disrupting a certain number of the crosslinks existing in the nondenatured complex before the local unwinding of the binding regions (a main step of denaturing complex formation) may proceed.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180311
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  • 3
    Electronic Resource
    Electronic Resource
    Wechselstrompolarographische kriterien der nucleinsäuredenaturierung (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 61-68 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical possibilities for investigation of nucleic acids with high molecular weight are restricted to the determination of the adsorption behavior. According to our experience the alternating current polarography (Breyer-polarography) is mainly appropriate for the characterization of changes in the secondary structure of DNA. The Breyer-polarogram shows the alternating current of the dropping electrode in dependence on their potential which varied from 0-2 v. negative against the normal calomel electrode (NCE). By addition of native DNA to the supporting electrolyte (buffer solution) the current drops down in the range of adsorption between 0 and 1 v. At 1.16 v. against NCE the desorption takes place together with the formation of a rounded desorption peak. The investigation was carried out in phosphate buffer solution 0.1m with 0.075m NaCl or in a phosphate buffer 0.18m with 0.03m NaCl. In the pH range above pH 8 NaOH was added to realize the higher pH values. A calf thymus DNA sample having a mean molecular weight of about 18 million was used. The concentration of DNA was 5 × 10-3-1 × 10-1 wt.-%. The polarographic measurements were performed with an a.c./d.c.-polarograph “GWP 564” from Akademiewerkstätten für Forschungsbedarf der Deutschen Akademie der Wissenschaften zu Berlin (DAW). The denaturation of the double helix causes a sharp desorption peak at negative potentials of the alternating current polarogram. This new criterion for the helix-coil transition is due to formation of unpaired bases. These nearly free bases undergo a specific adsorption and the desorption takes place within a narrow potential range. Nevertheless, at present time an electron transfer to particular bases cannot be excluded at special conditions. The increase of the sharp peak permits to estimate: (a) the melting curve of the double helix in agreement with spectroscopic measurements; (b) the photolysis of the double helix; (c) the strand separation in acid and alkaline solution. In the alkaline range the sharp peak increases and reaches its maximum at pH 〉 12. In the acid range, however, no sharp peak is observed and the rounded desorption peak decreases. Therefore, the best way of following the conformation changes is to measure the current difference between the curves of the solutions with and without DNA at electrocapillary-zero-potential. On the classical d.c.-polarogram one can measure small current steps only, which may be caused mainly by capacity changes. Moreover, the scission of the molecule by ultrasonic action can be followed. In this case the rounded peak of DNA increases but the sharp peak does not appear. Similar alternating current polarograms are obtained with poly-A in the native state, because helical and unordered regions coexist in the same molecule. The very rapid indication of these structure changes allows one to carry out kinetic measurements at a fixed potential with this method.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050107
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