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Proceedings of the National Academy of... Aug 1967
Topics: Chemical Phenomena; Chemistry, Physical; Energy Transfer; Fluorescence; Peptides; Polarography; Proline; Spectrum Analysis; Statistics as Topic
PubMed: 5233469
DOI: 10.1073/pnas.58.2.719 -
The Journal of Biological Chemistry Nov 1966
Topics: Adenine Nucleotides; Isocitrate Dehydrogenase; Kinetics; Mitochondria; NAD; NADP; Polarography; Saccharomyces
PubMed: 4380945
DOI: No ID Found -
International Journal of Molecular... Jul 2017Mitochondrial dysfunction plays a central role in the neuropathology associated with status epilepticus (SE) and is implicated in the development of epilepsy. While...
Mitochondrial dysfunction plays a central role in the neuropathology associated with status epilepticus (SE) and is implicated in the development of epilepsy. While excitotoxic mechanisms are well-known mediators affecting mitochondrial health following SE, whether hyperactivation of poly(ADP-ribose) polymerase-1 (PARP-1) also contributes to SE-induced mitochondrial dysfunction remains to be examined. Here we first evaluated the temporal evolution of poly-ADP-ribosylated protein levels in hippocampus following kainic acid-induced SE as a marker for PARP-1 activity, and found that PARP-1 was hyperactive at 24 h following SE. We evaluated oxidative metabolism and found decreased NAD⁺ levels by enzymatic cycling, and impaired NAD⁺-dependent mitochondrial respiration as measured by polarography at 24 h following SE. Stereological estimation showed significant cell loss in the hippocampal CA₁ and CA₃ subregions 72 h following SE. PARP-1 inhibition using -(6-Oxo-5,6-dihydro-phenanthridin-2-yl)- ,-dimethylacetamide (PJ-34) in vivo administration was associated with preserved NAD⁺ levels and NAD⁺-dependent mitochondrial respiration, and improved CA₁ neuronal survival. These findings suggest that PARP-1 hyperactivation contributes to SE-associated mitochondrial dysfunction and CA₁ hippocampal damage. The deleterious effects of PARP-1 hyperactivation on mitochondrial respiration are in part mediated through intracellular NAD⁺ depletion. Therefore, modulating PARP-1 activity may represent a potential therapeutic target to preserve intracellular energetics and mitochondrial function following SE.
Topics: Animals; Blotting, Western; Electroencephalography; Hippocampus; Mitochondria; Neurons; Poly (ADP-Ribose) Polymerase-1; Rats; Rats, Sprague-Dawley; Status Epilepticus
PubMed: 28704930
DOI: 10.3390/ijms18071502 -
The Journal of General Physiology Sep 1965This paper considers the way in which the oxygen reaction described by Dr. Nicholls and the ADP control reactions described by Dr. Racker could cooperate to establish a...
This paper considers the way in which the oxygen reaction described by Dr. Nicholls and the ADP control reactions described by Dr. Racker could cooperate to establish a purposeful metabolic control phenomenon in vivo. This has required an examination of the kinetic properties of the respiratory chain with particular reference to methods for determinations of oxygen affinity (K(m)). The constant parameter for tissue respiration is k(1), the velocity constant for the reaction of oxygen with cytochrome oxidase. Not only is this quantity a constant for a particular tissue or mitochondria; it appears to vary little over a wide range of biological material, and for practical purposes a value of 5 x 10(7) at 25 degrees close to our original value (20) is found to apply with adequate accuracy for calculation of K(m) for mammalia. The quantity which will depend upon the tissue and its metabolic state is the value of K(m) itself, and K(m) may be as large as 0.5 microM and may fall to 0.05 microM or less in resting, controlled, or inhibited states. The control characteristic for ADP may depend upon the electron flux due to the cytochrome chain (40); less ADP is required to activate the slower electron transport at lower temperatures than at higher temperatures. The affinity constants for ADP control appear to be less dependent upon substrate supplied to the system. The balance of ADP and oxygen control in vivo is amply demonstrated experimentally and is dependent on the oxygen concentration as follows. In the presence of excess oxygen, control may be due to the ADP or phosphate (or substrate), and the kinetics of oxygen utilization will be independent of the oxygen concentration. As the oxygen concentration is diminished, hemoglobin becomes disoxygenated, deep gradients of oxygen concentration develop in the tissue, and eventually cytochrome oxidase becomes partially and then completely reduced. DPN at this point will become reduced and the electron flow diminished. The rate of ATP production falls and energy conservation previously under the control of the ADP concentration will now be controlled by the diffusion of oxygen to the respiratory enzymes in the mitochondria. Under these conditions the rate of reaction of cytochrome oxidase with oxygen and the reaction of cytochromes with one another become of key importance. The rise of ADP and the depletion of energy reserves evoke glycolytic activity, and failure of biological function may result.
Topics: Adenine Nucleotides; Animals; Cytochromes; Electron Transport Complex IV; Fluorometry; In Vitro Techniques; Kinetics; Mitochondria; Oxidoreductases; Oxygen; Polarography; Rats; Succinate Dehydrogenase
PubMed: 4285727
DOI: 10.1085/jgp.49.1.163 -
Journal of Nuclear Medicine : Official... Jun 1979The reduction of [99Tc]pertechnetate was studied as a function of pH in complexing media of pyrophosphate, methylene diphosphonate (MDP), and ethane-1, hydroxy-1, and...
The reduction of [99Tc]pertechnetate was studied as a function of pH in complexing media of pyrophosphate, methylene diphosphonate (MDP), and ethane-1, hydroxy-1, and 1-diphosphonate (HEDP). Tast (sampled d-c) and normal-pulse polarography were used to study the reduction of pertechnetate, and normal-pulse polarography (sweeping in the anodic direction) to study the reoxidation of the products. Below pH 6 TcO4-was reduced to Tc(III), which could be reoxidized to Tc(IV). Above pH 10, TcO4-was reduced in two steps to Tc(V) and Tc(IV), each of which could be reoxidized to TcO4-. Between pH 6 and 10 the results differed according to the ligand present. In pyrophosphate and MDP, TcO4- was reduced in two steps to Tc(IV) and Tc(III); Tc(III) could be reoxidized in two steps to Tc(IV) and TcO4-. In HEDP, on the other hand, TcO4- was reduced in two steps to Tc(V) and Tc(III), and could be reoxidized to Tc(IV) and TcO4-. Additional waves were observed; they apparently led to unstable products.
Topics: Diphosphates; Etidronic Acid; Hydrogen-Ion Concentration; Oxidation-Reduction; Polarography; Technetium
PubMed: 43885
DOI: No ID Found -
Journal of Biomedicine & Biotechnology 2012The goal of the research was to identify the structural and functional characteristics of the rat's left ventricle under antiorthostatic suspension within 1, 3, 7 and 14...
The goal of the research was to identify the structural and functional characteristics of the rat's left ventricle under antiorthostatic suspension within 1, 3, 7 and 14 days, and subsequent 3 and 7-day reloading after a 14-day suspension. The transversal stiffness of the cardiomyocyte has been determined by the atomic force microscopy, cell respiration--by polarography and proteins content--by Western blotting. Stiffness of the cortical cytoskeleton increases as soon as one day after the suspension and increases up to the 14th day, and starts decreasing during reloading, reaching the control level after 7 days. The stiffness of the contractile apparatus and the intensity of cell respiration also increases. The content of non-muscle isoforms of actin in the cytoplasmic fraction of proteins does not change during the whole experiment, as does not the beta-actin content in the membrane fraction. The content of gamma-actin in the membrane fraction correlates with the change in the transversal stiffness of the cortical cytoskeleton. Increased content of alpha-actinin-1 and alpha-actinin-4 in the membrane fraction of proteins during the suspension is consistent with increased gamma-actin content there. The opposite direction of change of alpha-actinin-1 and alpha-actinin-4 content suggests their involvement into the signal pathways.
Topics: Animals; Cell Size; Cells, Cultured; Elasticity; Hindlimb Suspension; Mechanotransduction, Cellular; Myocardial Contraction; Myocytes, Cardiac; Rats; Rats, Wistar; Ventricular Function, Left; Weightlessness Simulation
PubMed: 23093854
DOI: 10.1155/2012/659869 -
Biological Psychology Jun 1985Transcutaneous partial oxygen tension (tc pO2) and skin blood flow (via heat clearance) were measured noninvasively in 22 male subjects who performed stress-inducing...
Transcutaneous partial oxygen tension (tc pO2) and skin blood flow (via heat clearance) were measured noninvasively in 22 male subjects who performed stress-inducing tasks (i.e. hand-grip exercise, cold pressor test, breath holding, hyperventilation and mirror-tracing). An analysis of variance and covariance was conducted for tc pO2, heat clearance, heart rate, respiration rate, finger pulse volume and systolic/diastolic blood pressure. Results indicate that tc pO2 can depict phasic cardiorespiratory challenge. Heat clearance proved to be less sensitive to the demand conditions used here. An analysis of covariance revealed a negative correlation between tc pO2 and blood pressure and respiration rate, as well as a positive correlation between tc pO2 and heat clearance. This suggests that phasic changes in tc pO2 are induced by both peripheral vasomotor activity and changes in arterial pO2.
Topics: Adult; Blood Flow Velocity; Blood Gas Analysis; Blood Pressure; Cardiovascular System; Heart Rate; Humans; Male; Monitoring, Physiologic; Oxygen; Polarography; Respiration; Skin; Skin Temperature; Stress, Physiological
PubMed: 4041519
DOI: 10.1016/0301-0511(85)90003-1 -
British Journal of Pharmacology Dec 19701. New halogenated 1,4-naphthoquinones were synthesized and together with other known 1,4-naphthoquinones, were screened for antibacterial activity by a turbidimetric...
1. New halogenated 1,4-naphthoquinones were synthesized and together with other known 1,4-naphthoquinones, were screened for antibacterial activity by a turbidimetric method, and for antifungal activity by the diffusion method on agar plates.2. The half-wave potentials and the influence on the oxidative phosphorylation of some of these compounds were determined.3. 2-chloro-3,2'-chloro-ethyl-1,4-naphthoquinone (half-wave potential=-187 mV) was the most active compound, completely inhibiting cell respiration.4. While the natural active naphthoquinones, vitamin K and ubiquinones, possess, as substituent, the electron repelling methyl group, the microbiologically active 1,4-naphthoquinones are substituted, in the quinone moiety, with electron attracting groups such as OH or Cl.5. The half-wave potentials can give only an initial indication of the activity of the compounds studied; a good correlation, on the contrary, can be found between the ultraviolet spectra of such compounds and their activity which seems to depend on the ability of active compounds to exist in an extensively conjugated structure and to form hydrogen bonds.
Topics: Agar; Antifungal Agents; Bacteria; Candida; Cysteine; Densitometry; Enterococcus faecalis; Escherichia coli; Glutathione; Methods; Naphthoquinones; Oxygen Consumption; Polarography; Shigella sonnei; Spectrum Analysis; Staphylococcus; Ubiquinone; Ultraviolet Rays; Vitamin K
PubMed: 4992959
DOI: 10.1111/j.1476-5381.1970.tb10662.x -
Journal of the Royal Society, Interface Jun 2017The evolution of structural colour mechanisms in biological systems has given rise to many interesting optical effects in animals and plants. The instance of the scarab...
The evolution of structural colour mechanisms in biological systems has given rise to many interesting optical effects in animals and plants. The instance of the scarab beetle is particularly distinctive. Its exoskeleton has a bright, golden appearance and reflects both right-handed and left-handed circularly polarized light concurrently. The chiral nanostructure responsible for these properties is a helicoid, in which birefringent dielectric planes are assembled with an incremental rotation. This study correlates details of the beetle's circularly polarized reflectance spectra directly with physical aspects of its structural morphology. Electron micrography is used to identify and measure the physical dimensions of the key constituent components. These include a chiral multilayer configuration comprising two chirped, left-handed helicoids that are separated by a birefringent retarder. A scattering matrix technique is used to simulate the system's optical behaviour in which the roles of each component of the morphological substructure are elucidated by calculation of the fields throughout its depth.
Topics: Animals; Birefringence; Coleoptera; Integumentary System; Light; Polarography; Surface Properties
PubMed: 28615493
DOI: 10.1098/rsif.2017.0129 -
Environmental Health Perspectives Mar 1986Techniques have been developed for detection, quantitation, and isolation of bacterial metallothioneins (MTs) from cyanobacterial species. These methods involve... (Comparative Study)
Comparative Study
Techniques have been developed for detection, quantitation, and isolation of bacterial metallothioneins (MTs) from cyanobacterial species. These methods involve differential pulse polarography and reverse-phase high-performance liquid chromatography (HPLC) and have allowed detection of picomole quantities of these high sulfhydryl content proteins. The prokaryotic molecule was found to be induced in the presence of Cd or Zn salts with regulation at the level of transcription. Cu was not found to induce synthesis of the prokaryotic MT. Exposure to the former metals resulted in a growth lag followed by simultaneous induction of MT synthesis and onset of growth. Amino acid analysis and N-terminal sequence analysis indicated that the bacterial MTs from cyanobacteria are unique, having many aromatic and aliphatic residues and no apparent association of hydroxylated or basic amino acids with cysteines. Although the characteristic Cys-X-Cys sequences were present, no apparent amino acid sequence homology with the eukaryotic MTs was found in the first 42 residues.
Topics: Amino Acid Sequence; Amino Acids; Brachyura; Cadmium; Copper; Cyanobacteria; Humans; Metallothionein; Polarography; Species Specificity; Zinc
PubMed: 3086079
DOI: 10.1289/ehp.866571