bluuebunny/crossref_metadata_2025 huggingface dataset:
The TLR4-TRIF Pathway Protects against H5N1 Influenza Virus Infection
Authors: Shinya Kyoko , Ito Mutsumi , Makino Akiko , Tanaka Motoko , Miyake Kensuke , Eisfeld Amie J. , Kawaoka Yoshihiro
Published: October 2011

Prestimulation of the TLR4 pathway with lipopolysaccharide (LPS) protects mice from lethal infection with H5N1 influenza virus. Here, we reveal that the TLR4-TRIF pathway is required for this protective effect by using mice whose TLR4-related molecules were knocked out. Microarray analysis of primary mouse lung culture cells that were LPS pretreated and infected with an H5N1 virus indicated that TLR3 mRNA was upregulated. Primary lung culture cells of TLR3 knockout mice showed no response to LPS pretreatment against H5N1 virus infection, suggesting that TLR3 is also involved in the preventive effect of LPS. Our data suggest that the TLR4-TRIF axis has an important role in stimulating protective innate immunity against H5N1 influenza A virus infection and that TLR3 signaling is involved in this pathway.
Magnetic properties of reaction products of chromocene and aliphatic alcohols
Authors: Votinský Jiří , Kalousová Jaroslava , Nádvorník Milan , Klikorka Jiří , Komárek Karel
Published: October 2011

Chromocene reacts with aliphatic alcohols (n = 1 to 4) at 20 °C to give cyclopentadiene and very reactive chromium(II) alcoholates. All the prepared alcoholates are antiferromagnetic compounds with the Weiss constant -280 to -170 K. The magnetic moment corresponds to contribution of four unpaired electrons and to d4 configuration of Cr(II) atom. An interpretation of the antiferromagnetism of the alcoholates is suggested.
Simplified analysis of a stochastic system
Authors: Herles Vladimír
Published: October 2011

Contradictious results published by different authors about the dynamics of systems with random parameters have been examined. Statistical analysis of the simple 1st order system proves that the random parameter can cause a systematic difference in the dynamic behavior that cannot be (in general) described by the usual constant-parameter model with the additive noise at the output.
Infrared spectra and conformation of substituted methyl cyclohexanecarboxylates and 2-hydroxycyclohexanecarboxylates
Authors: Vašíčková Soňa , Tichý Miloš
Published: October 2011

Infrared bands due to carbonyl and hydroxyl stretching vibration were measured for 32 esters of substituted cyclohexane and trans-decalin carboxylic acids and 2-hydroxy acids. The bands were computer-separated and most of them assigned to the appropriate rotamers. The conformational equilibrium in methyl trans-2-hydroxy-cis-4-isopropylcyclohexanecarboxylate was determined using comparison of integrated intensities of the hydroxyl bands of the mobile compound with those of the conformationally biased standards. The OH/COOCH3 vicinal interaction was found to be attractive (about 2.6 kJ mol-1).
Pea alcohol dehydrogenase: Substrate specificity and binding of coenzyme to enzyme
Authors: Stiborová Marie , Lapka Roman , Nováková Noemi , Leblová Sylva
Published: October 2011

Pea alcohol dehydrogenase (EC 1.1.1.1) shows a broad specificity with respect to aldehydes and alcohols. The pH-optimum of substrate oxidation is 8.7 and of substrate reduction 7.0. The enzyme is inhibited by ATP, adenosine, and adenine. The inhibition is competitive with respect to NAD. The inhibition by ATP is pH-dependent. The competitive character of the inhibition by adenine and its derivatives with respect to NAD indicates the importance of the adenine moiety of the coenzyme for its binding to the enzyme. Phenanthroline is a competitive inhibitor with respect to NAD, a mixed inhibitor with respect to ethanol and a noncompetitive inhibitor with respect to acetaldehyde. Experiments carried out simultaneously with ATP and phenanthroline show that the adenine moiety of NAD does not bind via the zinc atom to the enzyme protein.
Flow optimization by flow redistributors in wetted reactor II
Authors: Sára Antonín , Kolomazník Karel , Dolník Lubomír , Soukup Jaroslav
Published: October 2011

General procedure is proposed for flow optimization inside the packing of wetted reactors by use of flow redistributors. Improvement of efficiency and life time of packing are illustrated on the example of the refining hydrogenation reactor, where the flow inside the packing in the wall region is in equilibrium with the wall flow.
Electronic absorption spectra and π-electron structure of 2-propenylidene-1,2-dihydropyridine and its derivatives
Authors: Kuthan Josef , Ilavský Dušan , Krechl Jiří
Published: October 2011

The results of the PPP calculations of the singlet-singlet transitions of 1-methyl-3'-cyano-3'-alkoxycarbonyl-2-propenylidene-1,2-dihydropyridines II and 1-methyl-4-amino-3,3'-dicyano-3',5-di(methoxycarbonyl)-2-propenylidene-1,2-dihydropyridine (III) are in a satisfactory agreement with the experimental absorption curves in the visible and near ultraviolet region. Based on this finding, the absorption of the parent heterocyclic system of 2-propenylidene-1,2-dihydropyridine (I) is predicted. Some aspects of the π-electron structure of the substances I-III in the S0, S1 S2 and states are discussed.
Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone
Authors: Macháček Vladimír , El-bahai Said A. , Štěrba Vojeslav
Published: October 2011

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.
2-Deoxy-2-fluoro-D-glucosides. Preparation of 17-oxoestra-1,3,5(10)-trien-3-yl 2-deoxy-2-fluoro-β-D-glucopyranoside
Authors: Pacák Josef , Köllnerová Zdislava , Černý Miloslav
Published: October 2011

2-Deoxy-2-fluoro-D-glucopyranosides derived from phenol, estrone and 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose were prepared and the rates of acid hydrolysis of phenyl β-D-glucopyranoside and phenyl 2-deoxy-2-fluoro-β-D-glucopyranoside compared.
Study of 3-(5-X-2-furyl)acrylic acids and their methyl esters by gas chromatography
Authors: Rajniaková Oľga , Štetinová Jarmila , Kováč Jaroslav
Published: October 2011

The Kovát's indices and homomorphous factors of 3-(5-substituted-2-furyl)acrylic acids and their methyl esters were determined on stationary phases UCW 98 and OV 17 at 180 °C. It was found that the values of both chromatographic parameters increase with increasing polarity of the molecule.
Synthesis of 8-azidoadenosine 5'-phosphate
Authors: Houštěk Josef , Smrt Jiří
Published: October 2011

Sodium azide reacts with 8-bromoadenosine 5'-phosphate (I) in dimethyl sulfoxide under the formation of 8-azidoadenosine 5'-phosphate (II). The compound II was prepared alternatively from 8-azidoadenosine (V) and phosphoryl chloride.
Stochastic model of the nonideal flow mixer
Authors: Kudrna Vladimír
Published: October 2011

The flow mixer is described by use of the unidimensional stochastic model based on the earlier published general approach. It is demonstrated that on basis of the proposed model two individual models result which are most frequently used in chemical engineering for description of mixers and reactors: the dispersion model and model of the cascade of ideal mixers. On the basis of the model proposed it is also possible to derive the usual relation for calculation of the reactor conversion at macroflow.
Characterization of heavy crude oil fractions by means of the 13C NMR technique
Authors: Hájek Milan , Šebor Gustav , Lang Ivo , Starčuk Zenon , Weisser Otto , Vodička Luděk
Published: October 2011

The 13C NMR spectra of samples of heavy crude oil fractions were interpreted. The spectra of all samples were of the same character. In the region of the aliphatic carbon shifts, ten different carbon atom types were discerned; some possible structure types of hydrocarbons were attributed to them and the arrangement of the aromatic rings in a mean molecule of the samples examined was discussed.
Optimization of the multichamber crystallizer
Authors: Nývlt Jaroslav , Provazník Luděk
Published: October 2011

Mathematical model of the multichamber crystallizer is proposed and is solved for various combinations of temperature distributions among individual chambers. Results of a series of calculations have demonstrated that the most important factors are the temperatures in the first two chambers of the crystallizer while sufficient crystallization surface area in other chambers suffices for reduction of supersaturation even at a large temperature difference. Optimization of the five-chamber crystallizer with the mean size of product crystals chosen as the optimization criteria is then performed for constants corresponding to crystallization of Glauber salt.
The syn-anti dichotomy in bimolecular elimination of alkyltrimethylammonium salts: Steric and polar effects on rates and orientation in the competing pathways
Authors: Závada Jiří , Pánková Magdalena
Published: October 2011

The title problem has been investigated in two homologous series of positionally isomeric alkyltrimethylammonium salts, RCH2CHXC5H11 and RCHXCH2C5H11 (R = H, CH3, C2H5, n-C3H7, iso-C3H7 and tert-C4H9; X = N(+)(CH3)3Cl)(-), employing potassium tert-butoxide in tert-butanol and also potassium methoxide in methanol as the base-solvent combination. The overall rate constants of the individual olefin-isomer formation have been determined in these series and dissected, approximately, into the syn- and anti-components. The alkyl structure-reactivity relationship is thus obtained separately for the two complementary mechanisms of bimolecular elimination. The long-standing question whether steric or polar influence of alkyl group dominates in the complex reaction is re-examined on these grounds. Contrary to earlier extreme views it is shown that both the steric as well as the polar effects are very important, the former being operative mainly in the stereochemical (syn-anti) whereas the latter in the orientational (Hofmann-Saytzeff) control of the dichotomous reaction.
Decomposition of ferricenium cation in alkaline medium
Authors: Holeček Jaroslav , Handlíř Karel , Klikorka Jiří , Bang Nguyen Dinh
Published: October 2011

Stoichiometry and kinetics of decomposition of ferricenium compounds have been studied in alkaline medium. The reaction stoichiometry depends on type of the ferricenium compound. The decomposition rate of ferricenium ions is affected significantly by the presence of anions of inorganic salts with which ferricenium ion forms relatively stable complexes. From time course of the reaction probable mechanism of the decomposition process has been suggested, and its kinetic parameters have been determined.
Application of shift reagents in 1H and 19F NMR spectroscopy. Interactions with chlorofluoroalkanols C3, C4
Authors: Skácel František , Hájek Milan , Liška František , Trška Petr , Ksandr Zbyněk
Published: October 2011

The interaction Eu(FOD)3-substrate was examined in CDCl3 and CCl4 solutions by the methods of 1H and 19F NMR spectroscopy, and the stoichiometry, equilibrium constants, and limiting induced shifts of the adducts substrate-shift reagent were determined. 1-Propanol, 4-chloro-3,3,4-trifluoro-2-methyl-2-butanol, and 2,2,3,3-tetrafluoropropanol were employed as the substrates.
Influence of sulphuric acid concentration on current yield of peroxodisulphate
Authors: Balej Jan , Kadeřávek Martin
Published: October 2011

Overall anodic polarization curves and partial polarization curves of oxygen evolution and formation of peroxosulphates (S2O82- + SO52-) were measured potentiostatically on a smooth platinum anode in 1-13M-H2SO4 at 25 °C at a small degree of conversion of SO42- to S2O82- ions. The known dependences of the current yield of peroxodisulphate on the total concentration of sulphuric acid at various current densities were substantiated. The found results were used to explain mechanism of formation of S2O82- ions, according to which in contrast to previous explanations the possibility of simultaneous discharging of SO42- and HSO4- ions is considered with partial rates depending on the reaction conditions. A mathematical formulation of this mechanism is in qualitative agreement with experiments, an evidence for the probability of the mechanism. A correlation of the current yield with the actual concentrations of SO42- and HSO4- ions at various temperatures helps to further elucidate the negative influence of the temperature on the current yield.
Reactions of gallocyanine methyl ester with ions of noble earths
Authors: Kotouček Milan , Kučerová Marie , Lasovský Jan
Published: October 2011

Reactions of gallocyanine methyl ester with ten ions of noble earths have been followed spectrophotometrically in 10 to 30% (m/m) ethanol medium at pH 6.5 to 7.8. The trivalent cations and the ligand form complexes of ML3 type, their stability constants have been calculated by analysis of curves of concentration ratios and continuous variations.
Study of the reactions of alizarin green dyes with vanadates in the presence of cetyltrimethylammonium and Ag(1,10-phen)2+ cations
Authors: Son Nguyen Truong , Lasovský Jan , Ružička Eduard , Šimek Jiří , Szotkowská Jaroslava
Published: October 2011

The reactions of five dyes of the alizarin green series with vanadates in the presence of cetyltrimethylammonium (CTA+, S) or Ag(1,10-phen)2+ cations were studied. At lower concentrations of tenside than the cmc value, defined ternary complexes with composition VL2S4 or VL2S6 or quaternary complexes VL3[Ag(1,10-phen)2]9 are formed in solution. The equilibrium constants of the studied complexation reactions were determined and a method for the photometric and chelometric determination of vanadium were proposed.
Influence of alumina on selectivity of cobalt catalyst for oxidation of ammonia
Authors: Šimeček Antonín , Bernauer Bohumil , Zbuzek Bořivoj , Vosolsobě Jan , Jurovčák Ondrej
Published: October 2011

Alumina has been tested as carrier of active component of cobalt catalyst for oxidation of ammonia to nitrogen oxide. Mutual diffusion of the carrier and the active component has been found to take place under the oxidation conditions. In surface layer of the active component CoAl2O4 is formed which shows considerably lower selectivity (with respect to NO) than pure Co3O4. Time stability of the catalyst selectivity on alumina depends on temperature of its pretreatment before introduction of the active component.
Galvanostatic electrolysis with current reversal. Case of follow-up chemical reaction leading to electroactive substance after current reversal
Authors: Dračka Oldřich , Fischer Oldřich
Published: October 2011

For the galvanostatic method with current reversal, two cases are solved, in which an electroinactive substance M is formed by an irreversible electrode reaction and from this a substance P is formed by a chemical reaction. After a current reversal, P is consumed at the electrode. In one case, the substance P is moreover irreversibly converted to an electroinactive product Z. The corresponding schemes are M → P → Z and M ##e P. The solution is derived both for homogeneous chemical reactions and for reactions of substances accumulated on the electrode. The possibilities of distinguishing these cases from others and determination of the kinetic parameters are discussed.
Determination of low concentrations of dibenzyl sulfoxide in aqueous solutions
Authors: Vláčil František , Khanh Huynh Dang
Published: October 2011

A spectrophotometric method was developed for the determination of low concentrations of sulfoxide in water, relying on the formation of a leuco-compound from the reaction of L-tryptophan with p-dimethylaminobenzaldehyde and its oxidation by sulfoxide in hydrochloric acid medium. The optimum conditions for the determination were found by using the simplex method. The calibration curve, measured at 620 nm, is linear up to the sulfoxide concentration 7.5 . 10-5 mol l-1 (i.e. 17.3 ppm), the limit of determination is 0.1 ppm, the reproducibility, expressed as the relative standard deviation (for n = 6) is 3-4%. Oxidants interfere with the determination. Nitrates can be removed by means of a strongly basic anion exchanger in the chloride form. Mixture water-acetone (6 + 1) passing with a low flow rate should be applied to the elution of the partly sorbed sulfoxide.
Comparison of the viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate)
Authors: Hrouz Jaroslav , Ilavský Michal , Havlíček Ivan , Dušek Karel
Published: October 2011

The viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate) in the main transition region have been investigated. It was found that the time-temperature superposition could be carried out in the case of the penetration viscoelastic behaviour; the temperature dependence of the penetration and tensile shift factors was the same. The superimposed curves of the penetration and Young modulus allowed us to calculate the dependence of the Poisson ratio and thus to characterize the change in sample volume with deformation. It was demonstrated that the penetration method of determination of the viscoelastic behaviour is equivalent to the tensile method.
Vapour-liquid equilibrium in tetrachloromethane-isobutyl alcohol system
Authors: Rajiah Alagandala , Wichterle Ivan
Published: October 2011

The isobaric vapour-liquid equilibrium in the tetrachloromethane-isobutyl alcohol was measured by a recirculation method at 101.325 kPa. The data were correlated by the NRTL and the Margules equations.
Preparation of 6-amino-6-deoxy-D-allonic and 6-amino-6-deoxy-D-gluconic acid
Authors: Kefurt Karel , Čapek Karel , Kefurtová Zdeňka , Jarý Jiří
Published: October 2011

Partial tosylation of monoisopropylidene glucose I and monoisopropylidene allose II gave their 6-O-tosyl derivatives III and IV which were further converted to 6-azido-6-deoxy-D-glucose (XV ) and 6-azido-6-deoxy-D-allose (XVI) via 5,6-anhydrocompounds XII and X as intermediates. Oxidation of the products gave corresponding lactones XVIII and XVII. On their catalytic hydrogenation in methanol lactams XXII and XXI were prepared, while hydrogenation in water gave 6-amino-6-deoxy-D-allonic (XXIII) and 6-amino-6-deoxy-D-gluconic (XXIV) acids.
Analogues of oxytocin with esters of glutamic acid instead of glutamine in position 4: Synthesis of a compound with high and specific galactogogic activity
Authors: Lebl Michal , Barth Tomislav , Jošt Karel
Published: October 2011

The reaction of [4-glutamic acid]deamino-1-carba-oxytocin (Ib) with diazoalkanes yielded the corresponding methyl ester Ic and ethyl ester Id. Alternatively, the methyl ester was prepared by means of carbodiimide or thionyl chloride, or by treating the caesium salt of compound Ib with methyl iodide. [2-O-Methyltyrosine, 4-glutamic acid methyl ester]deamino-1-carba-oxytocin (Ih) was also synthetized. The structure of the analogues was verified and their galactogogic and uterotonic activities tested. Compound Ic had the highest galactogogic potency observed as yet (1 307 I.U./mg).
Noncataleptic potential neuroleptics: 2-Methyl-10-(4-methylpiperazino)- and -10-[4-(2-hydroxyethyl)piperazino]-10,11-dihydrodibenzo[b,f]thiepin
Authors: Valenta Vladimír , Jílek Jiří , Pomykáček Josef , Dlabač Antonín , Valchář Martin , Metyš Jan , Protiva Miroslav
Published: October 2011

[5-Methyl-2-(phenylthio)phenyl]acetic acid (XV) was synthesized on the one hand from the acid VIII using the known homologization technique via the alcohol X and nitrile XII, on the other from 5-methyl-2-(phenylthio)acetophenone (XIII) by means of the Willgerodt reaction. Via the intermediates XIX and XX, the synthesis led to 10-chloro-2-methyl-10,11-dihydrodibenzo[b,f]thiepin (XXI), giving by treatment with 1-methylpiperazine and 1-(2-hydroxyethyl)piperazine the title compounds III and IV. These compounds have low cataleptic and high central depressant activity; on the other hand, they do not influence the levels of dopamine metabolites in the rat brain which is considered an indication of their lacking the neuroleptic character.
Amino acid sequence of basic acrosin inhibitor from bull seminal plasma
Authors: Meloun Bedřich , Čechová Dana
Published: October 2011

The molecule of the inhibitor contains 57 amino acid residues whose sequence is the following: Pyr-Gly-Ala-Gln-Val-Asp-Cys-Ala-Glu-Phe-Lys-Asp-Pro-Lys-Val-Tyr-Cys-Thr-Arg-His-Ser-Asp-Pro-Gln-Cys-Gly-Ser-Asn-Gly-Glu-Thr-Tyr-Gly-Asn-Lys-Cys-Ala-Phe-Cys-Lys-Ala-Val-Met-Lys-Ser-Gly-Gly-Lys-Ile-Asn-Leu-Lys-His-Arg-Gly-Cys-Lys. The N-terminal group of the inhibitor is pyrrolidone carboxylic acid. The sequential data were obtained by analyses of peptides isolated from tryptic and chymotryptic digests of the oxidized or carboxymethylated inhibitor. The molecular weight of the inhibitor is 6 200.
The effect of solvation by acetone on the basicity of silylalkylamines
Authors: Papoušková Zlata , Fialová Vlasta , Chvalovský Václav
Published: October 2011

The relative basicity of fifteen methylethoxysilylalkylamines of the type (CH3)3-m(C2H5O)m.Si(CH2)nNH2 in acetone has been studied by potentiometric titration. For n 1 the basicity increases with increasing m, which is likely due to increasing electronic interaction of the oxygen of acetone with the silicon of silylalkylamines. The basicity of silylmethylamines (n = 1) changes nonsystematically, probably as a consequence of the competing action of opposite effects.
The C=O stretching vibration of aromaric α,β-unsaturated carbonyl and arylfurancarbonyl compounds
Authors: Perjéssy Alexander , Temkovitz Peter , Boykin David W.
Published: October 2011

Wavenumbers of the C=O stretching fundamental in the series of 145 conformers of aromatic α,β-unsaturated carbonyl and arylfurancarbonyl compounds were investigated in terms of Yukawa-Tsuno structure-reactivity equation. The parameters of these correlation were compared with the results obtained using Hammett or Brown equation. The separation and the transmission of normal and resonance substituent effects have been discussed in the individual series.
Noncataleptic neuroleptics: Potential metabolites of 2-chloro-10-[4-(2-hydroxyethyl)piperazino]-10,11-dihydrodibenzo[b,fthiepin
Authors: Valenta Vladimír , Svátek Emil , Dlabač Antonín , Bartošová Marie , Protiva Miroslav
Published: October 2011

The synthesis of nine potential metabolites of the title compound is being described. Using oxidation reactions, compound I was transformed to the S-oxide VII, A-oxide IX and A,S-dioxide X. Substitution reactions of 2,10-dichloro-10,11-dihydrodibenzo[b,f]thiepin with 1-ethoxycarbonylpiperazine, piperazine and ethylenediamine afforded the amines II, III, IV and XIII. Leuckart reaction of 2-chlorodibenzo[b,f]thiepin-10(11H)-one led in addition to the expected formamido derivative XI to the heptacyclic pyridine derivative XIV. Hydrolysis of compounds II and XI gave the secondary amine III and the primary amine XII. Oxidation of substances III, XII and XIII afforded the sulfoxides VIII, XV and XVI. Most of the prepared piperazine derivatives exhibit some central depressant, adrenolytic and antihistamine activity.
Determination of β-glycosidases, β-glucuronidase, and alkaline phosphatase by an enzyme electrode sensitive to phenol
Authors: Macholán Lumír
Published: October 2011

A rapid and relatively simple procedure is described for kinetic measurement of low activities of enzymes hydrolyzing phenol conjugates. Phenol generated by the enzyme reactions in the pH-optimum range 5.0-9.5 is continuously monitored by an oxygen membrane electrode of the Clark type. The surface of the electrode exposed to the solution is coated by a layer of chemically insolubilized polyphenol oxidase. The current response of the electrode, indicating the uptake of oxygen - diffusing from the solution together with phenol into the enzyme membrane - is proportional to the enzyme concentration (according to the kind of hydrolase in the range from 0.2 to at least 2-9 ncat). The dependences of the initial rate of enzyme reaction on enzyme and substrate concentration and the Km- and Vmax-values at optimal pH were measured with alkaline phosphatase, emulsin (β-glucosidase) and β-glucuronidase. The kinetic measurements showed that sweet almond emulsin contains two enzymes differing in their affinity toward phenyl-β-D-galactopyranoside.
Relation between surface tension and parameters of the Lennard-Jones equation for intermolecular potential
Authors: Šišková Marie
Published: October 2011

A relation has been derived between surface tension of pure substances and the parameters of the Lennard-Jones equation for intermolecular potential. The substitution for these parameters from empirical relations makes it possible to calculate the surface tension from critical temperature and critical volume of the substance considered. The derived relation has been verified by comparing the calculated values of surface tensions with the values measured for 22 pure substances.
The syntheses of methyl esters of pentadeconic acids with double branched chain
Authors: Tureček František , Turečková Olga , Julák Jaroslav
Published: October 2011

Methyl 2,4-dimethyltridecanoate, methyl 2,6-dimethyltridecanoate and methyl 2,8-dimethyltridecanoate were prepared in order to identify the components of the lipidic fractions from scotochromogenous bacteria.
Vasopressin analogs modified in position 3. Influence of changes of configuration
Authors: Zaoral Milan , Konopinska Danuta , Bláha Ivan , Krchňák Viktor , Škopková Jana , Machová Alena
Published: October 2011

The condensation of p-toluenesulfonyl-S-benzylcysteinyl-tyrosine azide with D-phenylalanine methyl ester afforded p-toluenesulfonyl-S-benzylcysteinyl-tyrosyl-D-phenylalanine methyl ester which was subsequently converted into the hydrazide and azide and coupled with glutaminyl-asparaginyl-S-benzylcysteine methyl ester. p-Toluenesulfonyl-S-benzylcysteinyl-tyrosyl-D-phenylalanyl-glutaminyl-asparaginyl-S-benzylcysteine methyl ester was condensed via the hydrazide and azide with prolyl-Nγ-p-toluenesulfonyl-αγ-diaminobutyryl-glycine amide. After removal of the protecting groups, closure of the disulfide bridge and purification, [3-D-phenylalanine, 8-α,γ-diaminobutyric acid]vasopressin was obtained which shows an appreciable antidiuretic effect of distinct specifity.
Asymmetric distribution of a metal in a heterogenized homogeneous catalyst
Authors: Řeřicha Roman , Vítek Antonín , Kolihová Dana , Sychra Václav , Šír Zdeněk , Hetflejš Jiří
Published: October 2011

Beads of a styrene-divinylbenzene copolymer modified by dimethylaminomethyl groups (an analogue of the Amberlyst A-21 anex), were used as a support for H2PtCl6 in the form of its trialkylammonium salt (about 12 wt.% of Pt). A distribution of the metal in individual beads was estimated analyzing traces of Pd in 107 single beads by flameless atomic absorption spectrometry (ratio Pd : Pt = 1 : 104). The distribution curve is assymetric and fits a three-parameter, log-normal curve (Johnson SL family of empirical distributions). The correlation coefficient between the weight of one bead and its absolute content of Pd was rather low (0.56). So, it is obvious that any biased sampling of such catalysts may cause misleading results, both in the elemental analysis and in catalytic data, especially in experiments carried out on millimole scale. A working procedure for an unbiased sampling of bead catalysts is proposed.
Structure of reaction product of 3-aminocrotononitrile with esters of alkoxymethylenecyanoacetic acid
Authors: Ilavský Dušan , Jehlička Václav , Kuthan Josef
Published: October 2011

Study of dipole moments of 3,5-dicyanopyrridine derivatives II-IV has shown that cyclocondensation of 3-aminocrotononitrile with esters of alkoxymethylenecyanoacetic acid gives the2-pyridone derivative I which can be transformed in 2-chloro- or 2-bromo derivatives IV and V by action of the respective halogenation agents. The substance IV is conversed into 2-iodo- and 2-dimethylamino derivatives VI and VII on action of HI and dimethylformamide, respectively. Alkylation of the 2-pyridone I with methyl iodide takes place at nitrogen atom to give the compound IX. The 1,4-dihydropyridine derivative X has been obtained by action of NaBH4 on IV.
Different activity of HZSM-5 and HNaY zeolites in the interaction with ethylene: Effect of water vapour
Authors: Nováková Jana , Kubelková Ludmila , Dolejšek Zdeněk , Jírů Pavel
Published: October 2011

The reaction of ethylene on HZSM-5 and HNaY zeolites, differing widely in acidity, was compared by means of IR and MS methods. Different surface and gaseous products were observed. The presence of water vapour effected mainly the activity of the HZSM-5 zeolite.
The infrared absorption spectra of mixed Ag3[AsO4, VO4] crystals
Authors: Hájek Bohumil , Muck Alexander , Smrčková Olga
Published: October 2011

Mixed Ag3[AsO4, VO4] crystals were prepared over the whole concentration range. In the 0-40% mol. Vanadate concentration range the mixed crystals are isostructural with Ag3AsO4 (T4d, Z = 2). Site- and factor group analyses were carried out for this space group and structure. Above 60 mol% vanadate, the mixed crystals are tetragonal with Ag3VO4 structure. It follows from the behaviour of the ν4AsO3-4 vibration that, in cubic mixed crystals with 40 mol% Ag3VO4, the site-symmetry T is reduced to effective site-symmetry C3 by the effect of lattice vibrations of the T(F) and R(F) types.
Paper chromatography of sulfinic acids and their detection
Authors: Marek Jan
Published: October 2011

A method of detection of aromatic sulfinic acids has been proposed, based on the treatment with nitrous gases, followed by spraying with a solution of the sodium salt of 2-naphthol-3,6-disulfonic acid (R-salt) and exposure to ammonia vapours. The mechanism of this method of detection has been elucidated. Chromatographic analysis of four aromatic sulfinic acids in several solvent systems has also been carried out.
Amperometric assay of vitamin C using an ascorbate oxidase enzyme electrode
Authors: Posádka Pavel , Macholán Lumír
Published: October 2011

An oxygen electrode of the Clark type, coated by a thin, active layer of chemically insolubilized ascorbate oxidase from squash peelings specifically detects by measuring oxygen uptake 10 to 400 μg of ascorbic acid in 3 ml of phosphate buffer. The record of current response to substrate addition lasts 1-2 min. The ascorbic acid values determined in various samples of fruit juices are in good agreement with the data obtained by titration and polarography. The suitable composition of the membrane and its lifetime and stability during long-term storage are described; optimal reaction conditions of vitamin C determination and the possibilities of interference of other compounds are also examined. Of the 35 phenols, aromatic amines and acids tested chlorogenic acid only can cause a positive error provided that the enzyme membrane has been prepared from ascorbate oxidase of high purity.
Liquid-liquid equilibrium. Possibilities of the regular solution theory for modelling liquid-liquid equilibrium in ternary systems
Authors: Novák Josef P. , Voňka Petr , Matouš Jaroslav , Pick Jiří
Published: October 2011

The applicability of the regular solution model for the description of the liquid-liquid equilibrium in ternary systems is discussed in the work and the conditions are established for the formation of two and three liquid phases. In the analysis it was found that certain forms of binodal curves cannot be obtained using only binary constants. On the other hand it appeared that the regular solution predicts a number of variants which have not been found experimentally yet. In the last part of the work, the effect of ternary constant is discussed as well.
Applicability of the van Laar equation to correlation of strongly non-ideal systems
Authors: Novák Josef P. , Palacká Eva , Voňka Petr , Pick Jiří
Published: October 2011

The performed analysis of the van Laar equation and its comparison with the results of analyses of the Redlich-Kister, NRTL and Wilson equations demonstrate that the Redlich-Kister equation have approximately the same range of applicability, the NRTL equation with a suitable choice of the parameter α allowing to attain higher limiting activity coefficients. For moderately asymmetric systems, the Wilson equation provides higher activity coefficients than other two-parameter equations but lower than the three-parameter ones. On the contrary, for very asymmetric systems, the Wilson equation allows to reach on the whole the highest limiting activity coefficients.
Vapour-liquid equilibrium correlation procedure in high pressure region
Authors: Wichterle Ivan
Published: October 2011

A new procedure is proposed for evaluation of binary interaction parameters required for the Redlich-Kwong-Soave method of calculation of high pressure vapour-liquid equilibria.
Perturbation theory of solutions of non-electrolytes. The effect of permanent and induced multipole interactions on excess thermodynamic functions of binary systems
Authors: Ševčík Miloš , Boublík Tomáš
Published: October 2011

Perturbation theory proposed to describe fluids with the multipole interactions was extended to the systems with significant induced interactions. The relations obtained were used to study the effect of the permanent and induced multipole interactions on excess thermodynamic functions of binary solutions formed by a simple fluid (interacting according to the Lennard-Jones pair potential) and a fluid with anisotropic intermolecular forces. Model solutions were studied first; the same procedure was then used to predict behaviour of the real systems cyclopentane-chloroform at 298.15 K and xenon-hydrogen chloride at 195.4 K. A considerable effect of anisotropic interaction on excess quantities of the model- as well as actual solutions was proved.
Paramagnetism of carbonization products formed from isotactic propylene containing synthetic zeolites
Authors: Rychlý Josef , Matisová-Rychlá Lydia , Plaček Ján
Published: October 2011

The paramagnetism was studied of products obtained by the carbonization of isotactic polypropylene with synthetic zeolites NH4Y and NiY and their mixtures with ammonium phosphate, N-bromosuccinimide and dibenzoyl peroxide. The interpretation of ESR signals in carbonized samples is based on the existence of stable carbenes. In the case of synergistic mixtures of flame retardants such as ammonium phosphate, N-bromosuccinimide and dibenzoyl peroxide in polypropylene the increased rate of polymer oxidation is observed at 190°C which may by attributed mainly to the presence of ammonium phosphate.
Loss of RKIP expression during the carcinogenic evolution of endometrial cancer
Authors: Martinho Olga , Faloppa Carlos Chaves , Neto Cristovam Scapulatempo , Longatto-Filho Adhemar , Baiocchi Glauco , da Cunha Isabela Werneck , Soares Fernando Augusto , Fregnani José Humberto Tavares Guerreiro , Reis Rui Manuel
Published: October 2011

Aims

Endometrial cancer is one of the most common cancers in women worldwide, but there is a lack of diagnostic markers for early detection of these tumours. The raf kinase inhibitory protein (RKIP) negatively regulates the Raf/MEK/ERK pathway, and the downregulation of RKIP is associated with tumour progression and metastasis in several human neoplasms. The aim of this study was to assess the expression levels of RKIP in endometrial cancer and determine whether this expression correlates with clinical outcome in these patients.

Methods

Tissue microarrays constructed using tissue samples from 209 endometrial adenocarcinomas, 49 endometrial polyps and 48 endometrial hyperplasias were analysed for RKIP expression by immunohistochemistry.

Results

The authors found that RKIP expression decreases significantly during malignant progression of endometrial cancer; it is highly expressed in non-neoplastic tissues (polyps 79.6%; hyperplasias 87.5%) and expressed at very low levels in endometrioid adenocarcinomas (29.7%). No correlations were observed between RKIP expression, clinicopathological data and survival.

Conclusion

This study demonstrated for the first time that RKIP expression is lost during the carcinogenic evolution of endometrial tumours and that the loss of RKIP expression is associated with a malignant phenotype. Functional studies are needed to address the biological role of RKIP downregulation in endometrial cancer.
Systematic study of the relationships between energy levels of (Tl+)2, (In+)2, (Ga+)2 dimer centers and the crystalline environment
Authors: Sun Qiang , Wang Lili , Gong Liangyu , Shi Jinsheng
Published: October 2011

In this paper, we present the first systematic study of correlations between energy levels of (Tl+)2, (In+)2, and (Ga+)2 dimer centers and the crystalline environment by using dielectric theory of chemical bonding for complex crystals. Our model has successfully built links between the EA′, EB′, and EC′ of these centers and the environmental factor h. The h has linear relationships with EA′, EB′, and EC′. The calculated results are in good agreement with the experimental values. This model can serve as a prediction tool and can be applied to assign the absorption band energies of (Tl+)2, (In+)2, and (Ga+)2 centers.
Facile one-pot synthesis of sugar–thiazolidinone derivatives
Authors: Darehkordi Ali , Saidi Kazem , Ghazi Somayeh
Published: October 2011

A simple, efficient, and cost-effective method for the synthesis of a series of sugar–thiazolidinone derivatives by a one-pot reaction of the corresponding thiosemicarbazone of d-galactose, d-glucose, and d-mannose compounds in the presence of dimethyl or diethyl acetylenedicarboxylate is described. Two different methods were used and high yields were obtained in both cases: (A) in EtOAC–H2O at an ambient temperature and (B) microwave irradiation under solvent-free conditions.
Hardness of Approximating Flow and Job Shop Scheduling Problems
Authors: Mastrolilli Monaldo , Svensson Ola
Published: October 2011

We consider several variants of the job shop problem that is a fundamental and classical problem in scheduling. The currently best approximation algorithms have worse than logarithmic performance guarantee, but the only previously known inapproximability result says that it is NP-hard to approximate job shops within a factor less than 5/4. Closing this big approximability gap is a well-known and long-standing open problem.

This article closes many gaps in our understanding of the hardness of this problem and answers several open questions in the literature. It is shown the first nonconstant inapproximability result that almost matches the best-known approximation algorithm for acyclic job shops. The same bounds hold for the general version of flow shops, where jobs are not required to be processed on each machine. Similar inapproximability results are obtained when the objective is to minimize the sum of completion times. It is also shown that the problem with two machines and the preemptive variant with three machines have no PTAS.
Circadian expression of clock and putative clock-controlled genes in skeletal muscle of the zebrafish
Authors: Amaral Ian P. G. , Johnston Ian A.
Published: October 2011

To identify circadian patterns of gene expression in skeletal muscle, adult male zebrafish were acclimated for 2 wk to a 12:12-h light-dark photoperiod and then exposed to continuous darkness for 86 h with ad libitum feeding. The increase in gut food content associated with the subjective light period was much diminished by the third cycle, enabling feeding and circadian rhythms to be distinguished. Expression of zebrafish paralogs of mammalian transcriptional activators of the circadian mechanism ( bmal1, clock1, and rora) followed a rhythmic pattern with a ∼24-h periodicity. Peak expression of rora paralogs occurred at the beginning of the subjective light period [Zeitgeber time (ZT)07 and ZT02 for roraa and rorab], whereas the highest expression of bmal1 and clock paralogs occurred 12 h later (ZT13–15 and ZT16 for bmal and clock paralogs). Expression of the transcriptional repressors cry1a, per1a/1b, per2, per3, nr1d2a/2b, and nr1d1 also followed a circadian pattern with peak expression at ZT0–02. Expression of the two paralogs of cry2 occurred in phase with clock1a/1b. Duplicated genes had a high correlation of expression except for paralogs of clock1, nr1d2, and per1, with cry1b showing no circadian pattern. The highest expression difference was 9.2-fold for the activator bmal1b and 51.7-fold for the repressor per1a. Out of 32 candidate clock-controlled genes, only myf6, igfbp3, igfbp5b, and hsf2 showed circadian expression patterns. Igfbp3, igfbp5b, and myf6 were expressed in phase with clock1a/1b and had an average of twofold change in expression from peak to trough, whereas hsf2 transcripts were expressed in phase with cry1a and had a 7.2-fold-change in expression. The changes in expression of clock and clock-controlled genes observed during continuous darkness were also observed at similar ZTs in fish exposed to a normal photoperiod in a separate control experiment. The role of circadian clocks in regulating muscle maintenance and growth are discussed.
Changing standard chow diet promotes vascular NOS dysfunction in Dahl S rats
Authors: Spradley Frank T. , Ho Dao H. , Kang Kyu-Tae , Pollock David M. , Pollock Jennifer S.
Published: October 2011

We hypothesized that vascular nitric oxide synthase (NOS) function and expression is differentially regulated in adult Dahl salt-sensitive rats maintained on Teklad or American Institutes of Nutrition (AIN)-76A standard chow diets from 3 to 16 wk old. At 16 wk old, acetylcholine (ACh)-mediated vasorelaxation and phenylephrine (PE)-mediated vasoconstriction in the presence and absence of NOS inhibitor, Nω-nitro-l-arginine methyl ester (l-NAME), was assessed in small-resistance mesenteric arteries and aortas. Rats maintained on either diet throughout the study had similar responses to ACh and PE in the presence or absence of l-NAME in both vascular preparations. We reasoned that changing from one diet to another as adults may induce vascular NOS dysfunction. In the absence of l-NAME, small arteries from Teklad-fed rats switched to AIN-76 diet and vice versa had similar responses to ACh and PE. Small-arterial NOS function was maintained in rats switched to AIN-76A from Teklad diet, whereas NOS function in response to ACh and PE was lost in the small arteries from rats changed to Teklad from AIN-76A diet. This loss of NOS function was echoed by reduced expression of NOS3, as well as phosphorylated NOS3. The change in NOS phenotype in the small arteries was observed without changes in blood pressure. Aortic responses to ACh or PE in the presence or absence of l-NAME were similar in all diet groups. These data indicate that changing standard chow diets leads to small arterial NOS dysfunction and reduced NOS signaling, predisposing Dahl salt-sensitive rats to vascular disease.
Spatiotemporal analysis of electrically evoked activity in the chicken optic tectum: a VSDI study
Authors: Weigel Stefan , Luksch Harald
Published: October 2011

The midbrain is an important processing area for sensory information in vertebrates. The optic tectum and its mammalian counterpart, the superior colliculus, receive multimodal, topographic information and contain a sensory map that plays a role in spatial attention and orientation movements. Many studies have investigated the tectal circuitry by cytochemistry and by characterization of particular cell types. However, only a few studies have investigated network activation throughout the depth of the tectum. Our study provides the first data on spatiotemporal activity profiles in the depth and width of the avian optic tectum. We used an optical imaging approach with voltage-sensitive dyes to investigate population responses at a high temporal and spatial resolution. With the necessary caution due to cell extension across several layers, we can thus link our findings tentatively with the general layout of the avian optic tectum. Single electrical stimuli in the retinorecipient layers 1–4 evoked a complex optical response pattern with two components: a short, strong transient response and a weaker persistent response that lasted several hundred milliseconds. The response started in layer 5 and spread within this layer before it propagated into deeper layers. This is in line with neuroanatomical and earlier physiological data. Analysis of temporal sequence and pharmacological manipulations revealed that these responses were mainly driven by postsynaptic activation. Thus tectal network responses to patterned input can be studied by voltage-sensitive dye imaging.
An in vitro spinal cord slice preparation for recording from lumbar motoneurons of the adult mouse
Authors: Mitra Pratip , Brownstone Robert M.
Published: October 2011

The development of central nervous system slice preparations for electrophysiological studies has led to an explosion of knowledge of neuronal properties in health and disease. Studies of spinal motoneurons in these preparations, however, have been largely limited to the early postnatal period, as adult motoneurons are vulnerable to the insults sustained by the preparation. We therefore sought to develop an adult spinal cord slice preparation that permits recording from lumbar motoneurons. To accomplish this, we empirically optimized the composition of solutions used during preparation in order to limit energy failure, reduce harmful ionic fluxes, mitigate oxidative stress, and prevent excitotoxic cell death. In addition to other additives, this involved the use of ethyl pyruvate, which serves as an effective nutrient and antioxidant. We also optimized and incorporated a host of previously published modifications used for other in vitro preparations, such as the use of polyethylene glycol. We provide an in-depth description of the preparation protocol and discuss the rationale underlying each modification. By using this protocol, we obtained stable whole cell patch-clamp recordings from identified fluorescent protein-labeled motoneurons in adult slices; here, we describe the firing properties of these adult motoneurons. We propose that this preparation will allow further studies of how motoneurons integrate activity to produce adult motor behaviors and how pathological processes such as amyotrophic lateral sclerosis affect these neurons.
State space analysis of timing: exploiting task redundancy to reduce sensitivity to timing
Authors: Cohen Rajal G. , Sternad Dagmar
Published: October 2011

Timing is central to many coordinated actions, and the temporal accuracy of central nervous system commands presents an important limit to skilled performance. Using target-oriented throwing in a virtual environment as an example task, this study presents a novel analysis that quantifies contributions of timing accuracy and shaping of hand trajectories to performance. Task analysis reveals that the result of a throw is fully determined by the projectile position and velocity at release; zero error can be achieved by a manifold of position and velocity combinations (solution manifold). Four predictions were tested. 1) Performers learn to release the projectile closer to the optimal moment for a given arm trajectory, achieving timing accuracy levels similar to those reported in other timing tasks (∼10 ms). 2) Performers develop a hand trajectory that follows the solution manifold such that zero error can be achieved without perfect timing. 3) Skilled performers exploit both routes to improvement more than unskilled performers. 4) Long-term improvement in skilled performance relies on continued optimization of the arm trajectory as timing limits are reached. Average and skilled subjects practiced for 6 and 15 days, respectively. In 6 days, both timing and trajectory alignment improved for all subjects, and skilled subjects showed an advantage in timing. With extended practice, performance continued to improve due to continued shaping of the trajectory, whereas timing accuracy reached an asymptote at 9 ms. We conclude that skilled subjects first maximize timing accuracy and then optimize trajectory shaping to compensate for intrinsic limitations of timing accuracy.