bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Oxidation of Catecholamines and 6-Hydroxydopamine by Molecular Oxygen: Effect of Ascorbate
Authors: Roginsky Vitaly A. , Barsukova Tatjana K. , Bruchelt Gernot , Stegmann Hartmut B. 
Published: August 2018

Abstract
Comparative kinetic studies on the oxidation of catecholamines (CA) (dopamine (DA), epinephrine (EP). norepinephrine (NEP)) serving as a neuromediator in the sympathetic nervous system, 3,4-dihydroxyphenylalanine (DOPA) and 6-hydroxydopamine (6-OHDA), a wellknown neurotoxic agent, were performed in the presence of ascorbate (AscH- ) in 50 mᴍ phosphate buffer, pH 7.40, at 37 °C by using a Clark electrode, EPR and the absorption spectroscopy. The oxidation of CA and DOPA alone was found to be a self-accelerating process, with quinone products (Q) acting as autocatalysts. The rate of oxygen consumption (Rox) increased with time and reached a steady-state level. A starting value of Rox increased in the order: EP < DOPA ≈ NEP ≪ DA ≪ 6-OHDA, whereas a steady-state value of Rox changed in the order: DOPA < DA < NEP ≪ EP ≪ 6-OHDA. The changes in Rox with time were found to correlate with the resistance of primary Q to the intramolecular cyclization.
The effect of AscH- on CA oxidation depended dramatically on whether AscH- was added to non-oxidized or preoxidized CA. Added to non-oxidized CA and DOPA, AscH- inhibited their oxidation (but not that of 6-OHDA). For the case of DA, a pronounced lag period was observed by both a Clark electrode and spectrophotometrically. The addition of AscH- to preoxidized CA, DOPA and 6-OHDA induced an increase in Rox a steadystate concentration of the ascorbyl radical. The kinetic behaviour of the systems was determined by two major factors: 1) AscH- suppressed the formation of Q, a catalyst for CA oxidation, most likely due to the reaction of AscH- with the semiquinone formed from CA; 2) Q derived both from CA and 6-OHDA catalyzed AscH- oxidation. The elevated cytotoxicity of 6-OHDA was found to be in part caused by the condition that 6-OHDA oxidation was not inhibited by AscH- and by the high efficiency of 6-OHDA as a redox cycling agent in combination with A scH−. These observations explain the very pronounced and prolonged cytotoxicity of 6-OHDA even at low concentrations that increases at elevated concentrations of AscH- .
Is Atmospheric Superoxide Vitally Necessary? Accelerated Death of Animals in a Quasi-Neutral Electric Atmosphere
Authors: Goldstein Naum , Arshavskaya Tatyana V. 
Published: August 2018

Abstract
To estimate the necessity of air ions (AIs) as a natural source of atmospheric gaseous superoxide for mammalia the effect of air ion deprivation on mice and rats was investigated. Ambient air deionization inside an experimental acrylic glass cage (AGC) was performed by electrostatic field, built up by acrylic glass surfaces. Under these conditions, four hours after the animals were placed into the AGC, the concentration of negative AIs was not detectable, the concentration of positive ions was (mean ± SD) 77 ± 18 ionsxcm-3. The negative and positive AI concentrations in identical silicate glass cages (control) were 482 ± 128 ionsxcm-3 and 660 ± 148 ionsxcm-3 respectively. It was found that the prolonged deficiency of AIs in ambient air leads to accelerated death of the animals. The life span of the deprived mice and rats was 16.2 ± 0.9 and 23.0 ± 1.1 days respectively. The pathological symptoms and ultrastructural changes in the adeno-and neurohypophysis in deprived animals observed strongly suggest that animal death is related to disturbances in neurohormonal regulation and pituitary insufficiency. The possible physiological need of AIs and atmospheric superox­ide, and its role in the development of environmental stress in human beings and in particular in premature infants is discussed.
New Botrydial Sesquiterpenoids from Hymenoscyphus epiphyllus
Authors: Thines Eckhard , Anke Heidrun , Steglich Wolfgang , Sterner Olov 
Published: August 2018

Abstract
Four new botrydial derivatives, hymendial (1), 7α-hydroxydihydrobotrydial (2), 7α-hy­droxy-10-O-methyldihydrobotrydial (4), and 7α-acetoxy-15α-methoxy-10-O-methyl-dihydro-botrydial (5) were isolated together with dihydrobotrydial (3) from the culture fluid of the ascomycete Hymenoscyphus epiphyllus. In addition, cytochalasin H (6a), 18-deoxycytocha-lasin H (6b) and (+)-mellein (7) were produced by this fungus. Hymendial (1), possessing an a, ß-unsaturated dialdehyde functionality, exhibits antimicrobial and cytotoxic activities and is mutagenic in the Ames Salmonella assay.
A Contribution of the Mitochondrial Adenosinetriphosphatase Inhibitor Protein to the Thermal Stability of the F0F1-ATPase Complex
Authors: Saad-Nehme Jorge , Bezerra Andre L. , Fornells Luz Alba M. , Silva Jerson L. , Meyer-Fernandes Jose R. 
Published: August 2018

Abstract
A complete inactivation is observed after a 3 min pre-incubation at 70 °C with mitochondrial F0F1-ATPase complex depleted of the ATPase natural inhibitor protein (ammonium-Sephadex submitochondrial particles) and activated MgATP-submitochondrial par­ticles (particles that after a 4 h-pre-incubation at 42 °C released the endogenous inhibitor protein). However, latent MgATP-submitochondrial particles (particles containing the inhibi­tor protein) pre-incubated under the same conditions are totally inactivated only after 15 min of pre-incubation. When ammonium-Sephadex particles are reconstituted with 20 μg/ml of purified ATPase inhibitor protein there is an increase of 15-fold in the half-time for ther­mal inactivation (t0.5), showing that the inhibitor protein protects the mitochondrial F0F1-ATPase complex against thermal inactivation.
Transformation of Cholanic Acid Derivatives into Pharmacologically Active Esters of Phenolic Acids by Heterogeneous Wittig Reaction
Authors: Ivanova Antoaneta , Milkova Tsenka , Galabov Angel S. , Nikolaeva Lubomira , Voynova Emilia 
Published: August 2018

Abstract
Steroid esters of cynnamic acid derivatives have been synthesized by a heterogeneous Wittig reaction under sonochemical conditions from the corresponding triphenylphosphonium bro­mides and unprotected phenolic aldehyds using K2CO3 as a base. 5β-Cholan-3α, 7α, 12α, 24-E-ferulate (11') exhibited a marked inhibitory effect on influenza virus A. The synthetic 3α, 24-E-diferulates of 5β-cholan-3α, 24-diol, 5β-cholan-3α, 12α, 24-triol and 5β-cholan-3α, 7α, 12α, 24-tetrol (8, 9 and 12) showed antitumor activity on leukemia P-388 in mice.
Chemical and Biological Characterization of Corticrocin, a Yellow Pigment Formed by the Ectomycorrhizal Fungus Piloderma croceum
Authors: Schreiner Thomas , Hildebrandt Ulrich , Bothe Hermann , Marner Franz-Josef 
Published: August 2018

Abstract
Corticrocin is synthesized by mycelia of Piloderma croceum in contrast to mycorradicin, which is deposited into the vacuoles of maize root cells upon colonization with arbuscular mycorrhizal fungi. Corticrocin is formed only when P. croceum is grown in darkness. This indicates that the compound is unlikely of a carotenoid origin which also follows from the chemical structure. Corticrocin is deposited at the surface of the fungal hyphae. The all-E- geometry of the polyunsaturated chain is confirmed by comparing the spectral and chrom atographic properties of the natural product with a synthetic reference.
Substrate Specificity of Chlorophyllase from Different Plants
Authors: Schoch Siegrid , Ihl Monica 
Published: August 2018

Abstract
The activity of chlorophyllase (chlorophyll-chlorophyllido-hydrolase, EC 3.1.1.14) ex­tracted from six different species was compared with enzyme extracted from leaves of Tree of Heaven. The chlorophyllase activity from Swiss chard was similar to the Tree of Heaven enzyme, all the others were less active or inactive. We tested the substrate specificity with bacteriochlorophyll a, chlorophylls a and b. pheophytins a and b and also the synthetic pig­ ments Zn pheophytins a and b and Zn pyropheophytin a. The natural pigments were the best substrates, but the Zn derivatives were also hydrolysed, except Zn pyropheophytin a which was accepted only by the enzyme extracted from the leaves of Tree of Heaven.
Nitidon, a New Bioactive Metabolite from the Basidiomycete Junghuhnia nitida (Pers.: Fr.) Ryv.
Authors: Gehrt Alexandra , Erkel Gerhard , Anke Timm , Sterner Olov 
Published: August 2018

Abstract
Nitidon, a highly oxidised pyranone derivative produced by the basidiomycete Junghuhnia nitida, has been isolated and its biological activities evaluated. The structure was determined by spectroscopic methods. Nitidon exhibits antibiotic and cytotoxic activities and induces morphological and physiological differentiation of tumor cells at nanomolar concentrations.
Hemolytic Activity of Aminoethyl-dodecanoates
Authors: Kleszczyńska H. , Łuczyński J. , Witek S. , Przestalski S. 
Published: August 2018

Abstract
The effect of new lysosomotropic compounds on red blood cell hemolysis and erythrocyte membrane fluidity has been investigated. In earlier studies it was shown that the compounds inhibit the growth of yeast and plasma membrane H+-ATPase activity. The study was per­ formed with eight aminoethyl esters of lauric acid variously substituted at nitrogen atom. Esters of dodecanoic acid were chosen for study because at that chain length dimethylaminoethyl esters showed maximum activity. The hemolytic activity of the substances studied exhib­its diversified activity in their interaction with the erythrocyte membrane: they differ in hemolytic activity and affect membrane fluidity differently. Erythrocyte membrane fluidity changes under the effect of those compounds which possess highest hemolytic activity. The hemolytic activity of the aminoesters investigated was found to follow a sequence that de­pended on basicity (i.e. ability of the protonated form formation) of the compound and its polar head group size. The most active are the compounds that possess not more than four carbon atoms substituted at nitrogen and highest pKa value.
Immobilization of Polymethylgalacturonase Producing Aspergillus niger on Luffa Sponge Material
Authors: Slokoska Ludmila S. , Angelova Maria B. 
Published: August 2018

Abstract
The vegetable sponge of Luffa cylindrica was studied as a matrix for the immobilization of Aspergillus niger 26. p roducer of polymethylgalacturonase (PMG). Entrapped spores could grow and multiply within the lattice of the sponge. The influence of loofa sponge inoculum content, initial spore inoculum content, and du ration of the growth cycle on the enzyme activity and mycelium growth was studied. The best yield of PMG was reach ed with 1 piece of loofa sponge (approx. 0.10 g dry weight), 109 spores per g carrier and 48 h duration of one cycle. Data obtained during long-term semicontinuous cultivation showed that production capacity increased significantly and the production period was extended more than 10 times compared with the free cell culture.
Circadian Synthesis of Light-Harvesting-Chlorophyll-Proteins in Euglena gracilis Is under Translational Control
Authors: Kiinne A. , Pistorius E. , Kloppstech K. , Groot E. de 
Published: August 2018

Abstract
Two proteins with apparent molecular masses of 17 and 24 kD that are synthesized in a circadian manner in the phytoflagellate Euglena gracilis, were recognized as proteins belong­ing to the family of light-harvesting-chlorophyll-proteins (LHCPs) of class I (17 kD) and of class II (24 kD). Identification was achieved by N-terminal sequencing of the proteins isolated from two-dimensional polyacrylamide gels and by detection with an anti-LHCP II se­rum. While it was found that the total amount of LHCPs remains almost constant, when Euglena is grown under diurnal conditions (12 h light and 12 h dark), we could show that the amount of newly synthesized 17 and 24 kD proteins varies about 20-fold with a maximum of synthesis in the light phase. In contrast, the analysis of the mRNA levels at different times revealed only minor differences in the stationary concentration of the LHCP specific mRNA, indicating that the control of LHCP synthesis is at the translational level. Principally, the same finding was obtained using inhibitors of transcription. Thus, it is concluded that the expression of LHCPs in Euglena gracilis in contrast to that of higher plants is primarily regulated at the translational level.
Theoretical Studies on the Tautomeric Properties of Diamino-5-formamidopyrimidines
Authors: Cysewski Piotr 
Published: August 2018

Abstract
The results of theoretical geometry prediction of formamidopyrimidine(fapy)-adenine and fapy-guanine tautomers are presented. Among 54 potential tautomeric structures of fapy-adenine the most stable structure corresponds to the diamino-keto isomer. The solvent effect has insignificant influence on the fapy-adenine tautomers succession. The fapy-guanine has 172 potential isomers. There are three most stable tautomers of this guanine derivative, which may exchange the order depending on the polarity of the environment. In vapour the most probable is the 4-enol-6-keto-diamino tautomer, while in water environment the 4,6-diketo-diamino isomer is dominant. A more polar solvent stabilises more polar fapy-guanine tauto­mers. The geometric parameters and point-atomic charges corresponding to most probable tau­tomers are also supplied.
Caffeoyl Quinic and Tartaric Acids and Flavonoids from Lapsana communis L. subsp. communis (Asteraceae)
Authors: Fontanel D. , Galtier C. , Viel C. , Gueiffier A. 
Published: August 2018

Abstract
Six hydroxycinnamic acids : caffeic acid, chlorogenic acid, 3,5-O-dicaffeoylquinic acid 2-O-caffeoyltartaric acid (caftaric acid) and 2,3-O-dicaffeoyltartaric acid (chicoric acid) have been isolated from Lapsana communis L. subsp. communis aerial parts. Among flavonoids, only isoquercitrin, luteolin and luteolin-7-O-β-glucuronide were identified. Except for chlorogenic acid, these com­ pounds represent the first report in Lapsana communis. Chicoric acid is the major phenylpropanoic constituent in this plant.
Protective Effect of Vitamin E in a Rat Model of Focal Cerebral Ischemia
Authors: Stohrer M. , Eichinger Andrea , Schlachter M. , Stangassinger M. 
Published: August 2018

Abstract
Under certain pathological conditions such as cerebral ischemia and reperfusion the occur­rence of free radicals is remarkably increased. However, only very little information is avail­ able on their quantitative relevance for the pathophysiology and final outcome of diseases. The aim of the present study was to evaluate the contribution of oxygen radicals in the pathogenesis of a stroke. For this purpose a rat model for stroke was used. Two of three vitamin E deficient groups were repleted with different dosages of DL-a-tocopherylacetate. N o signs of vitamin E deficiency could be observed. However, the weight gain during reple­tion was increased in the vitamin E repleted groups. Brain infarction was created by occlusion of the right middle cerebral artery (MCAO) for two hours. After 24 hours the measurements of infarct volumes were taken. The infarct volume of the group with the highest repletion dosage was significantly reduced by 81%. This was also expressed in a higher rate of gait disturbances after MCAO of the deficient animals. The control of vitamin E status exhibited a similar repletion-dependent level in plasma and brain. These results strongly support the hypothesis that the generation of oxygen radicals occurring during reperfusion is an impor­tant aspect of the pathophysiological mechanism in brain infarction.
Phytochemical Study and Antiinflammatory Properties of Lobelia laxiflora L
Authors: Philipov Stefan , Istatkova Ralitsa , Ivanovska Nina , Denkova Pavletta , Tosheva Kalina , Navas Hernàn , Villegas Juan 
Published: August 2018

Abstract
Three new piperidine alkaloids were isolated from stems, leaves and flowers of Lobelia laxiflora L. (Campanulaceae). The structures of racem. cis-8,10-diethyl-3,4-dehydrolobelidiol (1), racem. trans-8-ethyl-10-phenyl-3,4-dehydrolobelidiol (2) and racem. cis-8-ethyl-10-phenyl-3, 4-dehydrolobelidiol (3) were established by spectral analyses. The residues obtained from the ethanol extracts from stems (S), leaves (L), and flowers (F) were applied in carrageenan (Car)-and cobra venom (CV)-induced acute inflammation in mice. A suppression of paw edema formation at a dose of 100 mg kg-1 was established. In this study the antiinflammatory potential of Lobelia I. was regarded in connection with the complement system. The sequential activation and assembly into functional units of complement components can proceed via two different pathways, named classical (CP) and alternative (AP). The ability of the residues, nonalkaloid fractions, alkaloid fractions and the three alkaloids at a concentration from 0.125 to 1.0 mg ml-1 to inhibit complement activation and thus to prevent inflammatory process was estimated in vitro in human serum via both pathways. All of them inhibited complement activity with a predominant action on CP.
Inhibition of RNA Synthesis in vitro by Acridines - Relation between Structure and Activity
Authors: Piestrzeniewicz Mariola K. , Wilmańska Dorota , Studzian Kazimierz , Szemraj Janusz , Czyż Małgorzata , Denny William A. , Gniazdowski Marek 
Published: August 2018

Abstract
The effects of acridine derivatives (proflavine and 2,7-dialkyl derivatives, diacridines and triacridines, 9-aminoacridine carboxamides, and 9-anilinoacridine, amsacrine and its congeners) on overall RNA synthesis in vitro, on synthesis of initiating oligonucleotides and the binding of the enzyme to DNA were studied. The primary mechanism of action is related to inhibition of the enzyme binding to DNA. The acridines (intercalating or non-intercalating and bis-intercalating ligands) assayed here differ in the properties of their complexes with DNA. Correlation is generally observed between inhibition of RNA synthesis in vitro and cytotoxicity in cell cultures for di- and triacridines and 9-aminoacridine carboxamide derivatives. No relationship was found between the effect on RNA polymerase system and biological effects for amsacrine and its derivatives in contrast to the other series of acridines studied here. The aniline ring seems to decrease the inhibitory potency of a ligand. The discrepancy between the biological effect and RNA synthesis inhibition may be due to a different mechanism of cytotoxicity action of amsacrine which is a potent topoisomerase II poison.
Ultraviolet-B Induced Damage to Photosystem II in Intact Filaments of Spirulina platensis
Authors: Kolli Bala Krishna , Tiwari Swati , Mohanty Prasanna 
Published: August 2018

Abstract
When Spirulina platensis filaments were exposed to 0.75 mW.m-2.s-1 of ultraviolet-B radiation (the ultraviolet-B radiation under clear sky condition is ~1.0 mW.m-2.s-1), an inhibition in photosystem II activity was observed, the inhibition being 90% after 90 min exposure. Upon exposure to ultraviolet-B, the room temperature emission characteristics of Spirulina cells were altered when excited with light primarily absorbed by chlorophyll a or phycobilisomes. When the cells were exposed for 3 h the emission at 685 nm (F685), when excited at 440 nm (primarily chlorophyll a absorption), was enhanced compared to 715 nm (F 715) band of photosystem I suggesting a decrease in energy transfer from photosystem II to photosys­ tem I. Similarly, when the cells were excited at 580 nm (primarily the phycobilisomes), the ratio of emission intensity at 685 nm (F685) to that of 655 nm (F655) was decreased in the exposed cells. This change in emission characteristics seems to be linked with the uncoupling of the energy transfer from allophycocyanin to chlorophyll a of photosystem II. A small shift in emission peak positions was also indicated when excited either at 440 nm or 580 nm. Analysis of the fast induction of chlorophyll a transients in the presence and absence of 10 μm 3-(3,4-dichlorophenyl)-l,l-dimethylurea (DCMU) indicated that ultraviolet-B expo­ sure initially affects Qᴀ, the primary stable acceptor of photosystem II, and then the plastoquinone (PQ) pool. Our results on the loss in photosystem Il-catalyzed Hill activity with p-benzoquinone or dichlorobenzoquinone as electron acceptors also supports the contention that ultraviolet-B, even at low dose, initially alters the Qᴀ of photosystem II and subsequently PQ pool. The analysis of functional pool size of Spirulina suggests a substantial decrease in the functional pool size after 2 h UV-B exposure. These results indicate that in Spirulina low intensity of ultraviolet-B initially damages the reaction centre of photosystem II.
The Representation of Space and the Hippocampus in Rats, Robots and Humans
Authors: Burgess Neil , Donnett James G. , O ’Keefe John 
Published: August 2018

Abstract
Experimental evidence suggests that the hippocampus represents locations within an allocentric representation of space. The environmental inputs that underlie the rat’s representa­tion of its own location within an environment (in the firing of place cells) are the distances to walls, and different walls are identified by their allocentric direction from the rat. We propose that the locations of goals in an environment is stored downstream of the place cells, in the subiculum. In addition to firing rate coding, place cells may use phase coding relative to the theta rhythm of the EEG. In some circumstances path integration may be used, in addition to environmental information, as an input to the hippocampal system. A detailed computational model of the hippocampus successfully guides the navigation of a mobile robot. The model’s behaviour is compared to electrophysiological and behavioural data in rats, and implications for the role of the hippocampus in primates are explored.
Modular Organization of Motor Behavior
Authors: Bizzi E. , Saltiei P. , Tresch M. 
Published: August 2018

Abstract
The issue of translating the planning of arm movements into muscle forces is discussed in relation to the recent discovery of structures in the spinal cord. These structures contain circuitry that, when activated, produce precisely balanced contractions in groups of muscles. These synergistic contractions generate forces that direct the limb toward an equilibrium point in space. Remarkably, the force outputs, produced by activating different spinal-cord structures, sum vectorially. This vectorial combination of motor outputs might be a mecha­nism for producing a vast repertoire of motor behaviors in a simple manner.
How It Is to Be the Brain of a Monkey
Authors: Krüger J. 
Published: August 2018

Abstract
Hypotheses are presented on neural peculiarities of the monkey brain that distinguish monkeys from other mammals and man:
- The unique’ feature of cortical tissue is that it can be applied serially. It fulfils some requirements of a powerful visual system.
- The richness of visual as compared to other signals has yielded a basis for recognizing the bodily similarity of oneself to conspecifics. A visuo/motor coupling trained on oneself but applied to conspecifics (“aping”) evolved.
- Long series of (generalized visuo/visual) computations feasible in a very large cortex would produce excessive delays that would not correspond to outer world delays. The new human solution to this is an “offline” system in which temporal relationships are described by excitation patterns. This gives rise to a rapid expansion of the cortex.
- In humans, a “meaning” has to be attributed to the mutual (computational) relationships of excitation patterns in the offline system, by a reference to the corresponding relationships that would be valid in the normal (online) system. “Perception” is a corollary of this.
- The offline treatment of time, together with “aping”, leads to new types of helping and other social interactions.
- Monkeys may be compared to humans not using their offline system in the state of “absent- mindedness”.
- Experimental approaches departing from excitation patterns are discussed