bluuebunny/crossref_metadata_2025 huggingface dataset:
Syntheses of 17β-(2-maleimido)androstanes
Authors: Drašar Pavel , Havel Miroslav
Published: August 2011

Starting from pregnane derivatives, 17β-(2-maleimido)androstanes of 5α- and Δ5-series, with and without a 3β-acetoxy group, were prepared via methyl 3-androstanyl-3-cyano acrylates. The maleimidoandrostanes were synthesized as models of cardiotonic steroids.
Use of phenylacetyl group for protection of the lysine Nε-amino group in synthesis of peptides
Authors: Brtník František , Barth Tomislav , Jošt Karel
Published: August 2011

Nε-Phenylacetyllysine was used in the synthesis of deamino-lysine-vasopressin. The phenylacetyl protecting group is stable under conditions of peptide synthesis and can be removed by action of penicillin amidohydrolase (E.C.3.5.1.11) without damaging the built peptide chain.
Thermolytic digest of chicken pepsin
Authors: Baudyš Miroslav , Kostka Vladimír , Keilová Helena
Published: August 2011

Chicken pepsin prepared by the activation of pepsinogen was digested with thermolysin. The thermolytic digest was fractionated by chromatography on Sephadex G-25 fine. Certain fractions were subsequently subjected to ion exchange chromatography on Dowex 50-X2. The final purification was effected by paper chromatography and high voltage electrophoresis. By these procedures a series of homogeneous peptides was obtained; of the latter 54 nonoverlapping (save for a few exceptions) peptides are described in this paper. These peptides in addition to the thermolytic peptides reported before represent 80% of the linear structure of the whole molecule. The N-terminal amino acid sequence of chicken pepsin is discussed from the viewpoint of the recent data obtained by the analysis of the thermolytic digest.
Process characteristics of screw impellers with a draught tube for Newtonian liquids. Time of homogenization
Authors: Seichter Pavel
Published: August 2011

A conductivity method has been used to assess the homogenization efficiency of screw impellers with draught tubes. The value of the criterion of homochronousness, i.e. the dimensionless time of homogenization, in the creeping flow regime of Newtonian liquids is dependent on the geometrical simplexes of the mixing system. In particular, on the ratio of diameters of the vessel and the impeller and on the ratio of the screw lead to the impeller diameter. Expression have been proposed to calculate the mixing times. Efficiency has been examined of individual configurations of screw impellers. The lowest energy requirements for homogenization have been found for the system with the ratio D/d = 2.
Comparison of different methods for study of pore structure
Authors: Tomanová Dagmar , Zbuzek Bořivoj , Jeřábek Karel , Schneider Petr
Published: August 2011

Samples of controlled pore glass were used as model materials for comparison of pore distributions obtained by low temperature nitrogen adsorption/desorption and by mercury porosimetry. Pore distributions calculated from nitrogen sorption data by means of Broekhoff and de Boer equations seemed to be more reliable than results based on Kelvin equation or those obtained by mercury porosimetry, since the latter predict too narrow pores.
Ketimine-enamine tautomers of tetrazolo[1,5-a]quinoxaline derivatives
Authors: Klicnar Jiří , Toman Jaromír
Published: August 2011

4-Ethoxycarbonylmethylene-4,5-dihydrotetrazolo[1,5-a]quinoxaline and its α-substituted derivative display ketimine-enamine tautomeric isomerism. Their IR spectra and hydrazinolysis of 3,4-dihydro-3-oxo-quinoxaline analogues and related substances were studied.
Epimer of 7-deoxyaklavinone
Authors: Jizba Josef V. , Sedmera Petr , Vokoun Jindřich , Blumauerová Margita , Vaněk Zdenko
Published: August 2011

The structure (9R,10S)-7-deoxyaklavinone (VII) was assigned to a minor metabolite isolated from Streptomyces coeruleorubidus on the basis of 1H, 13C NMR and CD spectra. Evidence that compounds II and VII, isomeric with 7-deoxyaklavinone, are natural compounds is presented.
Effect of the structure of activated carbon on its saturation by hexachloroplatinic acid
Authors: Machek Vladimír , Šourková Marie , Růžička Vlastimil
Published: August 2011

The kinetics and equilibrium of adsorption of hexachloroplatinic acid on activated carbon was studied. The time course of saturation by chloroplatinic acid dissolved in water and in acetone, respectively, was examined on three types of activated carbon with different texture parameters. The effect of the support properties on the shape of the adsorption isotherm for the acid in solution was also investigated.
Single and competitive hydrodesulphurization of thiophene and benzo[b]thiophene on molybdenum catalysts
Authors: Pokorný Pavel , Zdražil Miroslav
Published: August 2011

The reactivity of benzo[b]thiophene and thiophene and the amount of 2,3-dihydrobenzo[b]thiophene and tetrahydrothiophene in the title reaction on sulphided Co-Mo-Al2O3 and MoS2 catalysts has been determined at the temperature range 543-623 K and hydrogen pressures 0.5-2.0 MPa in a tubular flow integral reactor. Under above conditions, benzo[b]thiophene was more reactive than thiophene and the difference in their reactivities in the competitive reaction was substantially greater than in the single reaction. The selectivity to the intermediate 2,3-dihydrobenzo[b]thiophene and tetrahydrothiophene in the reaction of benzo[b]thiophene and thiophene respectively, was measured in the whole region of total conversion. Based on these and reported data, the mechanism of hydrodesulphurization is discussed.
Synthesis of 1-benzyl-6-azauracil derivatives, chlorinated in the nucleus
Authors: Nováček Alois , Sedláčková Venuše , Vondráček Bohumír , Ševčík Bohumil , Bedrník Petr , Gut Jiří
Published: August 2011

Glyoxylic acid 2-benzylsemicarbazone derivatives, chlorinated in the aromatic nucleus (Ia-Id) were prepared either by reaction of glyoxylic acid semicarbazone with the corresponding benzyl chlorides or by treatment of benzylidene semicarbazide with substituted benzyl chlorides and reaction of the formed semicarbazides IIIa-IIId with glyoxylic acid. The semicarbazones Ia-Id were cyclized by heating with sodium hydroxide in ethylene glycol to give the corresponding 1-benzyl-6-azauracils IIa-IId.
Fluorinated tricyclic neuroleptics: Synthesis and pharmacology of 2-chloro-8-fluoro-4-(4-methylpiperazino)-4,5-dihydrothieno[2,3-b]-1-benzothiepin
Authors: Polívka Zdeněk , Holubek Jiří , Svátek Emil , Metyšová Jiřina , Protiva Miroslav
Published: August 2011

Diazotization of 4-fluoroanthranilic acid (V) and the following reaction with sodium disulfide gave the dithio diacid VII which was reduced with lithium aluminium hydride to 4-fluoro-2-mercaprobenzyl alcohol (XI). Its reaction with 2-chloro-5-iodothiophene afforded the alcohol XIII which was transformed via the chloride XIV and the nitrile XV to [2-(5-chloro-2-thienylthio)-4-fluorophenyl]acetic acid (XVI). Cyclization with phosphorus pentoxide in toluene resulted in 2-chloro-8-fluorothieno[2,3-b]-1-benzothiepin-4(5H)-one (XVIII) which was converted via the alcohol XIX to the chloro derivative XX. The substitution reaction with 1-methylpiperazine led to the title compound IV which is a long-acting and very potent tranquillizer but did not reveal, in the animal tests performed, the properties of a neuroleptic agent.
1-(4-Cyclopentylphenyl)ethylamine and derivatives: Synthesis and pharmacological screening
Authors: Vejdělek Zdeněk , Holubek Jiří , Bartošová Marie , Protiva Miroslav
Published: August 2011

Reduction of 4-cyclopentylacetophenone oxime gave the title compound II which was transformed by a combination of acylation, alkylation, reduction and substitution reactions to compounds III-XI. 2-Benzylcyclopentanone oxime was reduced to 2-benzylcyclopentylamine (XVI) and converted by a reaction with methylmagnesium iodide and by the following Ritter reaction to the formamide derivative XVIII which was used as the starting material for preparing amines XIX-XXI. The local anaesthetic and spasmolytic activity were the most typical neurotropic effects of derivatives of compound II. 2-Benzyl-1-methylcyclopentylamine and derivatives XIX-XXI have some hypotensive activity.
Addition of 2-methylthio-5-pyrimidinol and 5-methoxy-2-pyrimidinethiol to the acetylene triple bond
Authors: Buděšínský Zdeněk , Buděšínský Miloš , Šváb Alois
Published: August 2011

Reaction of 2-methylthio-5-pyrimidinol (I) with 2-methylthio-5-(2-propinyloxy)pyrimidine (II) in the presence of sodium methoxide gave cis-1,3-bis(2-methylthio-5-pyrimidinyloxy)-1-propene (IIIa) and 6-methyl-2-methylthiofuro-[3,2-d]pyrimidine (IV). On addition of I to 2-propinol cis-3-(2-methylthio-5-pyrimidinyloxy)-2-propenol (V) and the isomeric 2-(2-methylthio-5-pyrimidinyloxy)-2-propenol (VI) were formed. The latter when converted to chloro derivative VII was reacted with I to give 2,3-bis(2-methylthio-5-pyrimidinyloxy)-1-propene (VIII). From 1,3-dibromo-2-propanol and I 1,3-bis(2-methylthio-5-pyrimidinyloxy)-2-propanol (XI) was prepared which was converted to 1,3-bis(2-methylthio-5-pyrimidinyloxy)-2-bromopropane (XII) and then dehydrobrominated to a mixture of cis- and trans-1,3-bis(2-methylthio-5-pyrimidinyloxy)-1-propene (IIIa, IIIb). 5-Methoxy-2-pyrimidinethiol (XIV) reacts with 2-propinol similarly as I under formation of cis-3-(5-methoxy-2-pyrimidinylthio)-2-propenol (XV) and 2-(5-methoxy-2-pyrimidinylthio)-2-propenol (XVI). Compound I when reacting with 1-chloromethyloxirane gives both 1,2-epoxy-3-(2-methylthio-5-pyrimidinyloxy)propane (X) and 1-chloro-3-(2-methylthio-5-pyrimidinyloxy)-2-propanol (XIII), depending on reaction conditions.
Resolution of S-benzyl-DL-penicillamine with penicillin amidohydrolase
Authors: Šimek Petr , Barth Tomislav , Bárta Miroslav , Vojtíšek Vladimír , Jošt Karel
Published: August 2011

Racemic m-phenylacetyl-S-benzylpenicillamine was resolved into otical isomers by action of penicillin amidohydrolase (E.C.3.5.1.11) in high yield and optical purity.
Analysis of vibrational spectra of phenylphosphine, diphenylphosphine and their chloro derivatives. Overlay technique calculation of their force field in the reduced model approximation
Authors: Bergrová-Přádná Soňa
Published: August 2011

A normal coordinate analysis using the "reduced model" of benzene ring was carried out with (C6H5)nPX3-n (n = 1, 2; X = H, Cl) compounds. 46 wavenumbers of vibrational transitions of the phenyl- and phosphine group were determined by means of the overlay technique. The transferability of force constants used in this calculation is discussed and an improved assignment of vibrations in the phenyl and phosphine group, based on PED calculations is presented.
The density and the molar volumes of the system Ca(NO3)2-KNO3-H2O
Authors: Skokánek Mojmír , Sláma Ivo
Published: August 2011

The temperature and concentration dependence of the density of the system Ca(NO3)2-KNO3-H2O was studied over a temperature range from -20 to +75 °C and for concentrations given by ionic fractions of the potassium salt of 0.1, 0.2, 0.3, 0.4, and 0.5. The mole fraction of salts ranged from 0.052 to 0.27. The temperature and concentration dependence of calculated molar volumes has been correlated with an empirical equation, assuming additivity of the molar volumes of the salts. Deviations from the additivity principle are discussed and their quantitative description is proposed.
Preparation, properties and structure of some intermediate nido- and arachno-monocarbaboranes
Authors: Baše Karel , Štíbr Bohumil , Dolanský Jiří , Duben Josef
Published: August 2011

The 6-N(CH3)3-6-CB9H11 carbaborane reacts with sodium in liquid ammonia with the formation of 6-CB9H12- which was used as a starting compound for preparing the 4-CB8H14, 9-L-6-CB9H13 (L = (CH3)2S, CH3CN and P(C6H5)3), 1-(η5-C5H5)-1,2-FeCB9H10-, and 2,3-(η5-C5H5)2-2,31-Co2CB9H10- carboranes. The 4-CB8H14 compound was dehydrogenated at 623 K to give 4-(7)-CB8H12 carborane. Base degradation of 6-N(CH3)3-6-CB9H11 in methanol resulted in the formation of 3,4-μ-N(CH3)3CH-B5H10. The structure of all compounds was proposed on the basis of their 11B and 1H NMR spectra and X-ray diffraction was used in the case of the transition metal complexes.
Contribution to the study of inductive effect transmission in pyrrole derivatives
Authors: Janda Miroslav , Šrogl Jan , Holý Petr , Jakoubková Marie
Published: August 2011

Transmission of the inductive effect in pyrrole derivatives was investigated on 2-ethylpyrrole (VIa), 2-methylpyrrole (VIb), 2-dimethylaminomethylpyrrole (VIc), 2-hydroxymethylpyrrole (VId), methyl 2-pyrrolylacetate (VIe), 2-pyrrolylacetonitrile (VIf), 2-benzenesulfonylmethylpyrrole (VIg) and trimethyl(2-pyrrolylmethyl)ammonium iodide (VIh), by comparison of their relative basicities and acidities. These were determined by IR spectroscopy from the strength of donor-acceptor interactions of the pyrrole derivatives with suitable standard compounds. The found differences show good linear correlations with the σI substituent constants. On this basis, the transfer of the inductive effect in the given pyrrole series appears to be proportional.
Addition-cyclization reactions of 2-pyridyl isothiocyanate
Authors: Marchalín Miroslav , Světlík Jan , Martvoň Augustin
Published: August 2011

Addition-cyclization reactions of 2-pyridyl isothiocyanate with enamines and C-acids afforded derivatives containing pyrido[1,2-a]pyrimidine skeleton. Cyclization with a series of phenylhydrazones gave substituted triazolidines. The IR, UV, 1H NMR and 13C NMR spectra of the synthesized compounds are discussed.
Extracellular polysaccharide of Aspergillus flavus
Authors: Kardošová Alžbeta , Rosík Jozef
Published: August 2011

A crude extracellular polysaccharide was isolated by precipitation with ethanol from the culture medium of Aspergillus flavus, where the sole carbon source was D-galactose; purification afforded a homogeneous water-soluble polysaccharide in 0.05% yield on the weight of the employed carbon source. This polysaccharide had the relative molar weight 55 000 and [α]D22 -4.2° (c 0.5, H2O); upon total hydrolysis it afforded D-mannose and D-galactose in a 1 : 0.44 ratio. The products of hydrolysis of the methylated polysaccharide and also the course of partial acid and enzymic hydrolyses of the polysaccharide showed that the main chain was formed by (1 → 2) β-linked D-mannose units, of which each second, on average, was substituted by monomeric D-galactose units at C(6).
Geometric factor in dehydration of alcohols on X and Y zeolites
Authors: Sedláček Jiří
Published: August 2011

Geometric conditions for dehydration of alcohols on X and Y zeolites have been studied with the aid of computer constructed models. On the basis of these calculations conditions for two-site adsorption on different pairs of skeletal oxygen atoms in syn- and anti-elimination course of the reaction are discussed and the most suitable reaction sites are selected. Results of these computations were used to interpret experimental facts such as the preferential formation of cis-2-alkenes in the course of dehydration and the dependence of catalyst activity on the size and number of the cations present in zeolite skeleton.
Kinetics of oxidation of hypophosphitopentamminechromium(III) ion with periodate
Authors: Volárová Olga , Holba Vladislav
Published: August 2011

The kinetics of oxidation of hypophosphitopentamminechromium(III) ion with periodate was investigated as a function of the temperature, ionic strength, and concentration of perchloric acid. The reaction rate decreased with increasing ionic strength and concentration of perchloric acid. The redox reaction proper involving transfer of an oxygen atom is preceded by dissociation of hydrogen from the coordinated hypophosphite. The reactivity of the latter is compared with that of the free hypophosphite.
Perturbation of the fuchsone chromophore by 3,5-methyl substitution. Sterically crowded exocyclic double bond
Authors: Koutek Bohumír , Musil Lubomír , Velek Jiří , Lyčka Antonín , Šnobl Dobroslav , Synáčková Miroslava , Souček Milan
Published: August 2011

Several 3,5-methyl substituted fuchsones have been synthesized and characterized by means of UV and NMR spectroscopy as well as dipole moment measurements. Two basic types of behaviour of the longest wavelength band have been found for these derivatives in comparison to 2,6-substituted analogues i.e. hypochromic effect and bathochromic shift. These effects can be attributed to a steric crowding of the C(4)-C(7) double bonds. The role of the steric interactions in the ground state and in the excited state is discussed.
Synthesis and reactions of substituted furo[3,2-b]pyrrole derivatives
Authors: Krutošíková Alžbeta , Kováč Jaroslav , Dandárová Miloslava , Leško Ján , Ferík Štefan
Published: August 2011

Preparation of ethyl 2-methylfuro[3,2-b]pyrrole-5-carboxylate and 2-bromofuro[3,2-b]pyrrole-5-carboxylate, as well as alkylation and hydrolysis of ethyl 2-methylfuro[3,2-b]pyrrole-5-carboxylate, ethyl furo[3,2-b]pyrrole-5-carboxylate and ethyl (3,4-dichlorophenyl)furo[3,2-b]pyrrole-5-carboxylate, is described. IR, UV, 1H NMR, 13C NMR and mass spectra of the synthesized compounds were measured and interpreted.
The syntheses of biologically active 2-(4-hydroxybenzyl)-1-cyclohexanone derivatives
Authors: Wimmer Zdeněk , Romaňuk Miroslav
Published: August 2011

The syntheses of various 2-(4-hydroxybenzyl)-1-cyclohexanone derivatives are described in connection with the development of the research of substances with juvenile hormone activity.
Alkaloids from Papaver albiflorum subsp. austromoravicum KUBÁT, P. albiflorum PACZ. subsp. albiflorum and P. lecoquii LAMOTTE
Authors: Slavík Jiří , Slavíková Leonora , Dolejš Ladislav
Published: August 2011

From Papaver albiflorum subsp. austromoravicum KUBÁT berberine and (-)-α-canadine methohydroxide (in the form of iodide) were isolated as the main alkaloids, and allocryptopine, corytuberine and small amounts of protopine, rhoeadine and canadine as the minor components. Negligible amounts of mecambrine, thebaine, aporheine (?), corydine, isocorydine, scoulerine and traces of papaverrubines A, C, D and E, coptisine, corysamine, magnoflorine, α-stylopine methohydroxide and aporheine methohydroxide were also detected. P. albiflorum PACZ. subsp. albiflorum contains thebaine almost exclusively, accompanied by trace amounts of berberine, corytuberine, protopine (?), thebaine methohydroxide and aporheine methohydroxide. From P. lecoquii LAMOTTE berberine and corytuberine were isolated as the main alkaloids, as well as small amounts of protopine, a new alkaloid (-)-hexahydromecambrine-B, allocryptopine, rhoeadine and cryptopine. The presence of isocorydine and trace amounts of canadine, stylopine, mecambrine, papaverrubines A, C, D and E, corydine, scoulerine, coptisine, magnoflorine and α-stylopine methohydroxide was also detected.
Kinetics of the initial stage of initiated thermal oxidation of caprolactam and N-octylbutyramide
Authors: Lánská Božena , Postnikov Ludvig Michailovich , Aleksandrov Albert Leonidovich , Šebenda Jan
Published: August 2011

The thermal oxidation of ε-caprolactam or N-octylbutyramide in the liquid phase is a chain radical reaction. In the initial stage, the only reaction product is the corresponding amide hydroperoxide, formed from peroxy radicals by a second-order termination reaction. The rates of thermal oxidation reactions initiated with 7,7'-dicumenyl peroxide or 1,1'-azodi(cyclohexanecarbonitrile) and the rates of initiation reactions were measured in the temperature range 80-130 °C. Using the values thus obtained, the ratios of rates of the propagation and termination steps, k2 . k6-1/2, characterizing the oxidizability compounds, were calculated.
Hyperconjugation in organosilicon chemistry
Authors: Ponec Robert , Dejmek Luboš , Chvalovský Václav
Published: August 2011

The extent of delocalization interactions in organosilicon compounds was investigated by using the projection method of maximum localization. The results confirm that the accuracy of the localized model for organosilicon compounds is lower than that for analogous carbofunctional compounds.
Hydrogenation of nitrogen oxide on platinum-carbon catalysts in acidic medium
Authors: Paseka Ivo
Published: August 2011

Hydrogenation of nitrogen oxide in acid solutions on Pt-C catalysts proceeds in dependence on experimental conditions either in purely diffusion region or in the diffusion and kinetically controlled region. The boundary between these two processes shifts to the higher ratio of NO to H2 partial pressures with increasing platinum content and decreasing intensity of agitation.
5-Nitro-2-furylvinylation of aromatic polycyclic compounds
Authors: Hrabovský Ján , Dandárová Miloslava , Kováč Jaroslav
Published: August 2011

1-Bromonaphthalene, acenaphthene, phenanthrene, pyrene, chrysene, fluorene, guaiazulene, dibenzofuran, indole, N-methylindole, N-butylindole and carbazole react with (Z)-2-bromo-1-(5-nitro-2-furyl)ethylene in the presence of aluminium chloride to afford 2-substituted 1-(5-nitro-2-furyl)ethylenes. The structure of the prepared derivatives was confirmed by electron impact mass and 1H NMR spectroscopies.
Homogeneous hydrogenation and deuteration of pentacyclic triterpenoids: Double bonds in side-chains
Authors: Protiva Jiří , Lepša Luděk , Klinotová Eva , Klinot Jiří , Křeček Václav , Vystrčil Alois
Published: August 2011

The reduction of terminal double bonds in the side chains on the rings A and E of pentacyclic triterpenoids by means of tris(triphenylphosphine)rhodium chloride permits selective reduction of dienes and labelling with deuterium with a low scattering. The effect of the amount of the catalyst and the solvent used on the rate of reduction was studied in the case of 3β,28-diacetylbetulin.
Terpenoid derivatives of 4-hydroxypropiophenone as juvenoids and juvenogens. III
Authors: Kahovcová Jitka , Romaňuk Miroslav
Published: August 2011

Using reactions modifying 4-(3,7-dimethyl-2,6-octadienyloxy)propiophenone and 4-(3,7-dimethyl-2-octenyloxy)propiophenone a series of new potential juvenoids and juvenogens was synthetized.
A dilution dilatomer for measuring excess volumes
Authors: Cibulka Ivan , Holub Robert
Published: August 2011

A dilatomer is described which, as to its conception, stems from the dilatomer used by Kumaran and McGlashan (1977). The dilatomer was employed for measuring excess volume of the benzene-cyclohexane mixture at a temperature of 25 °C. The measured data agree well with those reported in the literature.
The influence of reaction conditions on the course of electrolytic preparation of ammonium peroxodisulphate: The influence of the relative degree of saturation of starting solution and of the temperature
Authors: Balej Jan , Thumová Milada , Špalková Hana
Published: August 2011

The current yield of the electrolytic preparation of concentrated solutions of ammonium peroxodisulphate was found to decrease with decreasing degree of saturation of the starting solution. It is therefore preferable to work with a starting solution of maximum allowable concentration with respect to the given temperature of electrolysis. As the temperature is increased, the current yield decreases progressively even if starting solution of maximum allowable concentration has been used; at the same time, the voltage on the electrolytic cell somewhat decreases. The observed effect of temperature on the current yield is a resultant of its effects on a number of simultaneously occurring electrochemical and chemical processes in the anode compartment.
CW-CO2 laser-induced and SF6-sensitized decomposition of trifluoroacetic anhydride
Authors: Pola Josef
Published: August 2011

CW-CO2 laser-induced and SF6-sensitized decomposition of trifluoroacetic anhydride affords carbonyl fluoride, carbon monoxide and trifluoroacetyl fluoride, the products different from those given by a conventional heating. The products and the kinetics of the laser-induced reaction reflect a different behaviour of presumably formed transient .CF2CO2. biradical under conditions precluding heterogeneous reaction on the reactor walls and point out that the fate of the .CF2CO2. species formed during the laser-powered homogeneous pyrolysis of trifluoroacetic acid and that of trifluoroacetic anhydride is under these conditions identical. The reverse order of thermal stability for trifluoroacetic acid and trifluoroacetic anhydride observed during the conventional and laser-induced pyrolysis suggests the laser-powered homogeneous process as a tool for modification of compounds' (relative) thermal stability ascertained under conventional thermal conditions including participation of heterogeneous surface reactions.
Continuous determination of phenol, vitamin C, lysine and glucose in flowing solutions by means of an amperometric enzyme electrode
Authors: Macholán Lumír , Londýn Petr , Fischer Jiří
Published: August 2011

A model apparatus is described for the continuous determination of compounds susceptible to catalytic oxidation by enzymes attached chemically to a membrane covering Clark's oxygen cell. The substrate concentration is estimated indirectly from the consumption of oxygen, which is proportional to the area under the curve registered at a constant potential of -0.65 V. A linear relation was found for phenol, ascorbic acid, L-lysine, glucose and polyamines. It is possible to analyze 15-30 samples in 1 h, depending on the flow rate of the carrier buffer.
An unusual rearrangement in hypobromous acid addition to 10β-vinyl cholestane derivatives
Authors: Kočovský Pavel , Tureček František
Published: August 2011

On treatment with hypobromous acid, 19-nor-10β-vinyl-5α-cholestan-5-ol (VIIa) rearranges to the spirocyclic ketone X. The rearrangement is postulated to proceed via the intermediate (19R)-bromonium ion VIIIa. The same reaction was observed with the methyl ether VIIb. The mechanism of the rearrangement was elucidated by 18O-labeling and product analysis.
Synthesis of 19-nor-10β-vinyl-5α-cholestane and its 5β-epimer
Authors: Kočovský Pavel
Published: August 2011

The title compound IX was synthesized from the monoacetate I in seven steps. The key point of the synthesis is selective hydrolysis of the diacetate II to III and removal of the substituent from the position 3 (IV → V). The 5β-isomeric olefin XX was prepared from the monoester XI in a similar manner. Conformational factors leading to differences in the reactivity of the ester groups in positions 3 and 19 in relation to the annelation of the A and B rings are discussed.
1H NMR spectra of some chloro-alkenes
Authors: Cawley Seán , Schraml Jan , Svoboda Petr , Ponec Robert , Chvalovský Václav
Published: August 2011

1H NMR spectra and electric dipole moments of a series of propene derivatives, (CH3)3-nCln.CCH=CH2 (n = 0-3), were measured and the spectra analyzed. Discrepancies in literature data on compounds with n = 0 and 3 are probably due to systematic spectrometer errors. Vinylic proton chemical shifts are found to vary linearly with n in the direction expected on the electronegativity ground (the variations with n occurs in the order HA > HB ≥ HC). Calculations show that even with the extreme reported values of C-C and C-Cl bond magnetic anisotropies, the shift variations with n cannot be accounted for by magnetic anisotropy effects of a freely rotating (CH3)3-nClnC group. Similar calculations rule out electric field effects as the dominant factor. On the other hand, the electron charge distribution, as obtained from CNDO/2 calculations, including d-orbitals and employing Del Bene-Jaffé parametrization, is linearly related to the vinylic proton shifts. This finding supports the earlier interpretation of NMR spectra of vinylsilanes in terms of back-bonding. The vinyl proton-proton coupling constants decrease with increasing n, the changes being larger in the constants which couple proton A (cis) to the other two.
Determination of heats of vaporization and some other thermodynamic quantities for four alkylcycloparaffins
Authors: Svoboda Václav , Charvátová Vladimíra , Majer Vladimír , Pick Jiří
Published: August 2011

Heats of vaporization and some other related thermodynamic quantities were determined for the four alkylcycloparaffins: ethylcyclopentane, n-butylcyclopentane, ethylcyclohexane and tert-butylcyclohexane. The temperature dependence of heats of vaporization was measured and employed for calculating standard heats of vaporization, internal and cohesive energies of vaporization, entropies of vaporization, and differences between heat capacities of liquids and vapours at constant pressure and along the saturation line of vapours.
Determination of the concentration dependence of the second derivative of Gibbs' energy with respect to composition on the basis of vapour-liquid equilibrium data
Authors: Novák Josef P. , Matouš Jaroslav , Šobr Josef , Pick Jiří
Published: August 2011

The course of the second derivative of Gibbs' energy with respect to composition for binary systems is evaluated. The representation of this quantity in terms of different correlation relations (the Wilson, NRTL and UNIQUAC equations and the ASOG and UNIFAC methods) is also discussed.
Study of polarization Raman spectra of natural thomsonite
Authors: Pechar František
Published: August 2011

The polarization Raman spectra were measured for a single crystal of thomsonite, a natural zeolite. The spectra were scanned in the wavenumber region of 50-4 000 cm-1 at room temperature. The results are discussed in terms of the structure of the mineral under study.
The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid
Authors: Podlahová Jana , Kratochvíl Bohumil , Langer Vratislav , Šilha Josef , Podlaha Jaroslav
Published: August 2011

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.
Solubility of thallium pertechnate in nitrate solutions
Authors: Mikulaj Vladimír , Mišianiková Eva , Macášek Fedor
Published: August 2011

Solubility of TlTcO4 was determined in water and in HNO3, NaNO3, NH4NO3, Ca(NO3)2, and LiNO3 aqueous solutions in concentrations 5-8 mol l-1. The solubility increases with increasing concentration of the electrolyte; the values measured were used for a calculation of the stoichiometric molar activity coefficients of the Tl+ and TcO4- ions. The activity coefficient values corrected for the fraction of the nonassociated Tl+ ions approach those of the base electrolytes up to their concentrations of 4-5 mol l-1.
Solvolysis kinetics and mechanism of 3-methyl-1,3-thiazolidine-2,4-dione
Authors: Macháček Vladimír , Štěrba Vojeslav , Zahradníčková Helena
Published: August 2011

The hydrolysis kinetics of 3-methyl-1,3-thiazolidine-2,4-dione have been studied in aqueous buffers and dilute NaOH solutions. The reaction proceeds via two base-catalyzed steps having different rates. In sodium methoxide solutions 3-methyl-1,3-thiazolidine-2,4-dione undergoes one-step methanolysis giving methyl thioglycolate anion as the final product. The rate-limiting step consists in decomposition of the anion CH3NCOSCH2COOCH3.
Transmission of polar effects arcoss the CH=CH link in styrylfuran system
Authors: Knoppová Viera , Beňo Anton , Dandárová Miloslava , Kováč Jaroslav
Published: August 2011

Transmission of polar substituent effect through the vinylidene grouping in 5-(4-X-styryl)-2-furaldehydes (X = H, Cl, Br, COOCH3, CN and NO2) was studied by polarographic reduction of the aldehyde group as well as by kinetics of their condensation with malononitrile. The obtained transmission coefficients π' were compared with the corresponding values for systems, containing other links between the benzene and furan nuclei. Thermodynamic parameters of the condensation with malononitrile were determined. The transmission of polar effects is discussed also from the point of view of 1H NMR spectra.
Solid-gas equilibrium in the binary system lithium iodide-water
Authors: Hejtmánková Jiřina , Černý Čestmír , Jettmar Luděk
Published: August 2011

An investigation has been made of the equilibria of hydration in the system solid lithium iodide-water vapour in the temperature interval covering the range of existence of the solid hydrates, using a dynamic method in a flow apparatus. From measured equilibrium pressures, the changes of the thermodynamic functions accompanying these reactions were determined and the values of the heats of formation, of the Gibbs energies of formation and of the absolute entropies of the solid mono-, di- and trihydrate of lithium iodide at 298.15 K were calculated.
Study of potential curves by UHF-type methods. Homonuclear diatomics of second row atoms
Authors: Klimo Viliam , Tiňo Jozef
Published: August 2011

Potential curves of Li2, Be2, B2, C2 and N2 molecules in their ground states have been calculated in the minimal gaussian basis complemented by the bond functions. Comparison of results of the UHF, PUHF and UMP2 methods with experimental curves shows that the UMP2 method gives qualitatively correct description of dissociation of all the studied molecules. For each of the molecules peculiarities of the potential curves are discussed from the point of view of their description by the UHF-type methods in the basis used.
On the transient Leveque's problem with an application in electrochemistry
Authors: Wein Ondřej
Published: August 2011

The electrochemically induced unsteady mass transfer to a uniform shear flow from a local wall electrode subjected to a step change in electrochemical potential is studied. Due to neglecting the streamwise diffusion, the problem has two solutions which however differ only insignificantly. The resulting transient characteristics of current densities have a simple analytical form suitable for an efficient data treatment.
Transient convective diffusion for the hydrodynamic rear stagnant region, with an application in electrochemistry
Authors: Wein Ondřej
Published: August 2011

Time dependence of mean current densities after the step change in concentration of depolarizer on the surface of convective electrode under conditions of limiting diffusion currents for the axially symmetrical configuration of the rear critical region is approximately determined by a new type of the similarity integral method.
Reactions of 2-, 3-, 4-pyridine-2-propenoates and 2-, 3-, 4-quinoline-2-propenoates with diazomethane
Authors: Ferles Miloslav , Salamon Miloš , Podpěrová Pavla
Published: August 2011

Cycloaddition reactions of esters of trans-pyridine-2-propenoic acids, Ia-Id, and methyl trans-quinoline-2-propenoates Ie-Ig with diazomethane gave 4-pyridyl-2-pyrazoline-3-carboxylates IIa-IId and 4-quinolyl-2-pyrazoline-3-carboxylates IIe-IIg, respectively.
IR spectra of methyltetrosides and their monomethyl ethers in the region of valence vibration of hydroxyl groups
Authors: Jarý Jiří , Marek Miroslav
Published: August 2011

IR Spectral absorption bands ν(OH) (3 700 to 3 400 cm-1) of the both anomers of methyl D-threofuranoside, methyl-D-erythrofuranoside, and their monomethyl ethers have been studied in dilute tetrachloromethane solution. For these 11 compounds positions and intensities of individual bands are discussed with respect to possible formation of intramolecular hydrogen bonds.
Effect of school-based interventions on physical activity and fitness in children and adolescents: a review of reviews and systematic update
Authors: Kriemler S , Meyer U , Martin E , van Sluijs E M F , Andersen L B , Martin B W
Published: August 2011

Background

School-based interventions are thought to be the most universally applicable and effective way to counteract low physical activity (PA) and fitness although there is controversy about the optimal strategy to intervene.

Objectives The objective of this review was to summarise recent reviews that aimed to increase PA or fitness in youth and carry out a systematic review of new intervention studies.

Methods

Relevant systematic reviews and original controlled and randomised controlled school-based trials with a PA or fitness outcome measure, a duration of ≥12 weeks, a sufficient quality and involvement of a healthy population aged 6–18 years that were published from 2007 to 2010 were included.

Results

In these reviews, 47–65% of trials were found to be effective. The effect was mostly seen in school-related PA while effects outside school were often not observed or assessed.

Conclusions

The school-based application of multicomponent intervention strategies was the most consistent, promising strategy, while controversy existed regarding the effectiveness of family involvement, focus on healthy populations at increased risk or duration and intensity of the intervention. All 20 trials in the review update showed a positive effect on in-school, out-of-school or overall PA, and 6 of 11 studies showed an increase in fitness. Taking into consideration both assessment quality and public health relevance, multicomponent approaches in children including family components showed the highest level of evidence for increasing overall PA. This review confirms the public health potential of high quality, school-based PA interventions for increasing PA and possibly fitness in healthy youth.
Physical activity and obesity in children
Authors: Hills Andrew P , Andersen Lars Bo , Byrne Nuala M
Published: August 2011

Globally, obesity is affecting an increasing proportion of children. Physical activity plays an important role in the prevention of becoming overweight and obese in childhood and adolescence, and reducing the risk of obesity in adulthood. Puberty and the following adolescent period are acknowledged as particularly vulnerable times for the development of obesity due to sexual maturation and, in many individuals, a concomitant reduction in physical activity. In many Western settings, a large proportion of children and adolescents do not meet recommended physical activity guidelines and, typically, those who are more physically active have lower levels of body fat than those who are less active. Active behaviours have been displaced by more sedentary pursuits which have contributed to reductions in physical activity energy expenditure. Without appropriate activity engagement there is an increased likelihood that children will live less healthy lives than their parents. Owing to the high risk of overweight adolescents becoming obese adults, the engagement of children and adolescents in physical activity and sport is a fundamental goal of obesity prevention.
Hollow spheroids beyond the invasive margin indicate the malignant potential of colorectal cancer
Authors: Tamura Koichi , Yokoyama Shozo , Ieda Junji , Takifuji Katsunari , Hotta Tsukasa , Matsuda Kenji , Oku Yoshimasa , Watanabe Takashi , Nasu Toru , Kiriyama Shigehisa , Yamamoto Naoyuki , Nakamura Yasushi , Shively John E , Yamaue Hiroki
Published: August 2011

Objective

Tumour budding formed by histologically undifferentiated cancer cells beyond the border of the tumour margin is associated with lymph node metastasis. However, hollow tumour nests, a possible histologically advanced phenotype of tumour budding, have not been discussed. We examined whether hollow spheroids exist beyond the border of the invasive margin and are associated with metastasis and prognosis. Moreover, we suggest that carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) isoform balance is associated with hollow spheroid formation.

Methods

Immunohistochemical analyses with CEACAM1 and M30 as an apoptosis marker were performed to examine the importance of hollow spheroid CEACAM1 expression and central cell apoptosis in hollow spheroid formation. The correlations between the presence of hollow spheroids beyond the invasive margin and the clinicopathological characteristics of 314 patients with colorectal cancer were retrospectively evaluated. A 3D culture with colorectal cancer cells transfected with CEACAM1 cDNA or shRNA was used to determine whether CEACAM1 isoform balance controls colorectal hollow spheroid formation.

Results

Hollow spheroid formation accompanying central cell apoptosis was confirmed by M30 staining and serial section with CEACAM1 staining. Of the 314 patients, 96 (30.4%) were classified as having hollow spheroids. The presence of hollow spheroids is an independent risk factor for metastases and shorter survival. In 3D culture, CEACAM1 isoform balance modulated hollow spheroid formation of colorectal cancer cells.

Conclusions

Hollow spheroid formation beyond the border of the tumour margin in colorectal cancer is more important than tumour budding for the prediction of malignant potential.
HER2 gene amplification in patients with breast cancer with equivocal IHC results
Authors: Meijer Sybren L , Wesseling Jelle , Smit Vincent T , Nederlof Petra M , Hooijer Gerrit K J , Ruijter Henrique , Arends Jan Willem , Kliffen Mike , van Gorp Joost M , Sterk Lotus , van de Vijver Marc J
Published: August 2011

Aims

Equivocal human epidermal growth factor receptor 2 protein (HER2) (2+) immunohistochemistry (IHC) is subject to significant interobserver variation and poses a challenge in obtaining a definitive positive or negative test result. This equivocal test result group accounts for approximately 15% of all tumours, and for optimal guidance of HER2 targeted therapy, a further analysis of quantification of gene copy number and amplification status is needed for patients with early or metastatic breast cancer.

Methods

553 breast-cancer specimens with equivocal HER2 IHC(2+) test results were collected and subsequently centrally retested by chromogenic in situ hybridisation (CISH), and HER2 gene copy numbers per tumour cell nucleus were determined.

Results

Using CISH, 77 of 553 equivocal HER2 IHC(2+) test result cases (13.9% of total) showed high levels of HER2 gene amplification (≥10.0 gene copies per nucleus), and 41 of 553 (7.4% of total) showed low-level HER2 gene amplification (6.0–9.9 gene copies per nucleus). In 73.6% of cases, no amplification of the HER2 gene was shown, and in only 4.9% of cases was an equivocal test result by CISH observed (4.0–5.9 gene copies per nucleus).

Conclusions

Testing by CISH of all equivocal HER2 IHC(2+) test result provides a definitive guidance in HER2 targeted therapy in 95.1% of cases. A significant proportion (21.3%) of patients with equivocal IHC(2+) test results show amplification of the HER2 gene.
Abnormal spiral artery remodelling in the decidual segment during pregnancy: from histology to clinical correlation
Authors: Avagliano Laura , Bulfamante Gaetano Pietro , Morabito Alberto , Marconi Anna Maria
Published: August 2011

Introduction

Modification of the spiral arteries with loss of the muscular vascular wall, invaded by the trophoblasts, represents the goal of the physiological vascular adaptation during human implantation. When physiological vascular changes do not occur, an unfavourable evolution of gestation may develop as suggested by uterine biopsies studies.

Aims

To evaluate the prevalence of the abnormal spiral arteries modification (ASAM) through the routine examination of placentas, to identify maternal predisposing factors and to examine the correlations between the histological lesion and pregnancy outcome.

Methods

1534 consecutive singleton pregnancies were retrospectively analysed. An extensive histological and clinical investigation was performed.

Results

ASAM was present in 5.8% pregnancies. When compared with cases without ASAM, cases with ASAM exhibited a higher prevalence of pre-eclampsia (10% vs 2%), placental abruption (5.5% vs 0.3%), preterm premature rupture of membranes (7% vs 1.3%) and intrauterine fetal death (18% vs 2.2%). Multivariate analysis showed that the maternal body mass index represents the major maternal pregestational factor that can influence the prevalence of ASAM (OR=1.8, 95% CI 1.1 to 3 in cases with BMI>30 kg/m2).

Conclusion

The abnormal modification of the decidual segment of the spiral arteries is identifiable at the time of the conventional histopathological placental evaluation and is associated with adverse pregnancy outcome. The identification of the cause of the unfavourable evolution of pregnancy is fundamental for parents, both for counselling and for prevention; the identification of ASAM in such pregnancies might provide additional valuable information.
Measuring interobserver variation in a pathology EQA scheme using weighted κ for multiple readers
Authors: Wright Karen C , Melia Jane , Moss Sue , Berney Dan M , Coleman Derek , Harnden Patricia
Published: August 2011

Background

A Urological Pathology External Quality Assurance (EQA) Scheme in the UK has reported observer variation in the diagnosis and grading of adenocarcinoma in prostatic biopsies using basic κ statistics, which rate all disagreements equally.

Aim

The aim of this study is to use customised weighting schemes to report κ statistics that reflect the closeness of interobserver agreement in the prostate EQA scheme.

Methods

A total of 83, 114 and 116 pathologists took part, respectively, in three web-based circulations and were classified as either expert or other readers. For analyses of diagnosis, there were 10, 8 and 8 cases in the three circulations, respectively. For analyses of Gleason Sum Score, only invasive cases were included, leaving 5, 5 and 6 cases, respectively. Analyses were conducted using customised weighting schemes with ‘pairwise-weighted’ κ for multiple readers.

Results

Analysis of diagnosis for all circulations and all readers gave a composite κ value of 0.86 and pairwise-weighted κ (κp–w) value of 0.91, both regarded as ‘almost perfect’ agreement. This was due to the high proportion of responses that showed partial agreement. Analysis of Gleason Sum Score gaveκ=0.38 andκp–w=0.58 over all circulations and all readers, indicating that discrepancies occur at the boundary between adjacent grades and may not be as clinically significant as suggested by composite κ.

Conclusion

Weighted κ show higher levels of agreement than previously reported as they have the advantage of applying weighting, which reflects the relative importance of different types of discordance in diagnosis or grading. Agreement on grading remained low.