bluuebunny/crossref_metadata_2025 huggingface dataset:
HINDERED INTERNAL ROTATION IN BORON HALIDE COMPLEXES OF N,N-DIMETHYLFORMAMIDE
Authors: Gore E. S. , Blears D. J. , Danyluk S. S.
Published: May 2006

The barriers to internal rotation about the CN partial double bond in N,N-dimethyl-formamide (DMF) and its complex with BF3 have been determined in tetrachloroethane (TCE) by nuclear magnetic resonance measurements. The activation energy for rotation Ea, increased from 6.2 ± 0.3 kcal mole−1 for DMF to 14.5 ± 1.1kcal mole−1 for DMF•BF3. Values of ΔH≠ and ΔS≠ were also derived. Low field shifts of the methyl resonances and an increase in the relative shifts between the two methyl groups were observed on complex formation. The formyl coupling constant to the methyl groups was larger for the complex than for pure DMF. In addition, for DMF—BCl3 evidence for the presence of two types of complex was found. The present results are compatible with BF3 and BCl3 complexing to the amide oxygen atom. The energy changes for internal rotation and J variation are attributed to changes in the π character of the CN bond due to stabilization of the charged resonance from [Formula: see text] upon complex formation.
THE ALKALOIDS OF PAPAVERACEOUS PLANTS: LIII. ESCHSCHOLTZIA CALIFORNICA CHAM.
Authors: Manske Richard H. F. , Shin Kju Hi
Published: May 2006

Several lots of Eschscholtzia californica have been investigated and the following alkaloids have been identified, in addition to a new alkaloid which has been named eschscholtzine: protopine, allocryptopine, cryptopine, chelerythrine, and lauroscholtzine, which is a new name for N-methyllaurotetanine. Some plant lots did not yield cryptopine and not sufficient chelerythrine for positive identification.
FORMATION OF O-β-D-GLUCOPYRANOSYL- AND O-β-D-GALACTOPYRANOSYL-MYO-INOSITOLS BY GLYCOSYL TRANSFER
Authors: Gorin P. A. J. , Horitsu K. , Spencer J. F. T.
Published: May 2006

Enzyme extracts or growing cells of Sporobolomyces singularis catalyzed glycosyl transfer from cellobiose or lactose to polyhydroxylic acceptors. The substituted hydroxyl, in each instance, had hydroxylic neighbors which appeared to have a role in the reaction. To show whether the pyranoid ring oxygen of glycosyl acceptors has an effect on the reaction, the substitution positions on pyranoid and myo-inositol acceptors are compared. Glucosyl transfer to the 1- and 5-positions of (1R)-myo-inositol3 and galactosyl transfer to the 5-position occurs. The configuration of hydroxyl groups adjacent to the position substituted is the same in these products as in the corresponding pyranoid derivatives. The pyranoid ring oxygen, therefore, has little effect on the glycosyl transfer reactions.
RAMAN SPECTRUM OF CRYSTALLINE AND LIQUID SO2
Authors: Anderson A. , Savoie R.
Published: May 2006

The Raman spectrum of crystalline sulfur dioxide has been recorded at several temperatures between 9 and 185 °K. The main features are in accord with those predicted from the factor group analysis for the known structure of the crystal. Additional peaks were also observed, some arising from isotopic species and lattice fundamentals. As an aid to the assignment of several other bands, the spectrum of the liquid has also been recorded to distinguish the specifically crystalline features. Possible causes of these extra peaks, such as combinations with lattice modes, crystalline defects, and impurities, are briefly discussed.
CARBOHYDRATES CONTAINING NITROGEN IN A FIVE-MEMBERED RING AND AN ATTEMPTED SYNTHESIS OF A CARBOHYDRATE WITH NITROGEN IN A SEVEN-MEMBERED RING
Authors: Szarek W. A. , Jones J. K. N.
Published: May 2006

Lead tetraacetate oxidation of 6-acetamido-6-deoxy-D-galactose (IX) yielded a syrup which was converted to a compound formulated as 4-acetamido-4-deoxy-1,2-O-isopropylidene-D-threofuranose (XII). The same syrup was obtained by alkaline degradation of the product of oxidation of 5-acetamido-5-deoxy-D-xylose diethyl dithioacetal (XVII) with peroxypropionic acid. Treatment of compound XII with p-toluenesulfonyl chloride yielded crystalline 4-acetamido-4-deoxy-1,2-O-isopropylidene-3-O-p-tolylsufonyl-D-threofuranose (XIII).Demercaptalation of 6-acetamido-2,3,4,5-tetra-O-acetyl-6-deoxy-D-galactose diethyl dithioacetal (XX) with mercuric chloride and cadmium carbonate in aqueous acetone did not yield a nitrogen-containing septanose ring but an acyclic derivative.
THE NATURE OF ASSOCIATION BETWEEN MOLECULES OF N-METHYLPYRROLE
Authors: Anderson Hugh J.
Published: May 2006

The dilution of N-methylpyrrole by an inert solvent causes a change in the values of the proton chemical shifts which has been interpreted to support a "closed cyclic dimer" type of association between molecules. Equilibrium constants have been computed for the monomer–dimer system at two temperatures. The proton chemical shifts have been determined for the pure liquid at a series of temperatures covering a wide range. The effects of dilution in several different solvents have also been investigated.
THE N.M.R. SPECTRUM OF 2,3,5-TRIMETHYL-2,3,5-TRICYANOHEXANE. UNUSUAL TEMPERATURE DEPENDENCE OF MAGNETIC NONEQUIVALENCE
Authors: Smith P. , McLeskey III J. J.
Published: May 2006

not available
ALICYCLIC KETYLS: I. ANGULAR DEPENDENCE OF HYPERFINE COUPLING AND CONFORMATIONAL MOBILITY OF CYCLOHEXANONE KETYLS
Authors: Lown J. W.
Published: May 2006

The electron paramagnetic resonance (e.p.r.) spectra of ketyls derived from cyclopentanone and 4-tert-butyl, 4-methyl, 3-methyl, and unsubstituted cyclohexanone have been recorded in dimethoxymethane at room temperature. The proton hyperfine splittings (aH) observed with rigid ketyls are consistent with a dihedral angular (θ) dependence of hyperfine coupling of the form, aH = 4.8 + 9.6 cos2 θ. Conformational averaging of the hyperfine coupling is observed with 4-methyl, 3-methyl, and unsubstituted cyclohexanone ketyls. The conformer populations calculated from the e.p.r. spectra are in accordance with A values for the methyl group derived from non-radical cyclohexane compounds.
BASICITIES OF METHYLTHIO- AND PHENYLTHIO-ANILINES
Authors: Rae Ian D.
Published: May 2006

not available
THE H− FUNCTION IN AQUEOUS ALCOHOLS CONTAINING BASE
Authors: Bowden Keith
Published: May 2006

not available
PROTON MAGNETIC RESONANCE SPECTRA OF D-GLUCOPYRANOSE POLYMERS
Authors: Glass C. A.
Published: May 2006

The proton magnetic resonance spectra of carbohydrates in deuterium oxide solution were obtained and considered with respect to probable conformation. The anomeric proton signal occurred at lowest field and was easily recognized. In the various glucose derivatives investigated, this signal occurred from 4.62 to 5.25 τ for equatorial protons and from 5.12 to 5.65 τ for axial protons. Within each of these ranges, the chemical shifts varied inversely with the electronegativity at the C1 site, as calculated by the technique of Gordy (1). Variable electronegativity at C1 accounts for the overlap of ranges for equatorial and axial protons, thereby bringing the n.m.r. data into agreement with assignment of the C1 chair form of the pyranose ring to the linear polymers of D-glucopyranose. The orientation of the glucopyranose rings in cyclodextrins is shown to preclude ring current effects, and the up-field chemical shifts of these materials are shown to be consistent with the C1 form.
THE AMINO PROTON SHIFTS OF SOME SUBSTITUTED ANILINES IN CYCLOHEXANE
Authors: Yonemoto T. , Reynolds W. F. , Hutton H. M. , Schaefer T.
Published: May 2006

The amino proton shifts of 41 ortho, meta, and para substituted anilines at low concentrations in cyclohexane are reported. The shifts for meta and para substituents correlate with Hammett σ constants and it is shown that they are probably proportional to the π-electron density on the nitrogen atom. These shifts also correlate with the pKa values of the corresponding anilinium ions in aqueous acid. The amino proton shifts for the ortho substituents, apart from methyl groups, follow a correlation line which lies about 0.5 p.p.m. to low field from that for the meta and para substituents. This negative deviation is discussed in terms of a weak hydrogen bonding interaction with the ortho substituents and the H—N—H bond angles as derived from infrared data.
X-RAY STUDY OF LIQUID AsBr3
Authors: Hoge R. , Trotter J.
Published: May 2006

The structure of liquid arsenic tribromide has been investigated by deriving the radial distribution function from X-ray intensity data recorded with monochromatic Cu Ka radiation. The results are consistent with pyramidal molecules with dimensions similar to those in the vapor and solid states. Most of the intermolecular distances in the crystal are preserved in the liquid.
THE KINETICS OF THE INHIBITED AUTOXIDATION OF TETRALIN. II
Authors: Howard J. A. , Ingold K. U.
Published: May 2006

The kinetics of the oxidation of tetralin inhibited by a number of phenols have been examined. The chain transfer reaction between phenoxy radicals and hydroperoxides is subject to both polar and steric effects. The rate of this reaction is increased by electron-attracting substituents on the phenol and is decreased both by ortho-alkyl groups on the phenol and by an increase in the size of the substituents on the hydroperoxides.
ABSOLUTE RATE CONSTANTS FOR HYDROCARBON AUTOXIDATION: I. STYRENE
Authors: Howard J. A. , Ingold K. U.
Published: May 2006

Absolute rate constants for the uninhibited oxidation of styrene have been obtained by the rotating sector technique. The rate constants for the propagation (kp), bimolecular termination (kt), and a kinetically first order termination (kx) for 2 M styrene In chlorobenzene can be represented by[Formula: see text]The rate constant for the reaction of poly(peroxystyryl) peroxy radicals with 2,6-di-t-butyl-4-methylphenol can be represented by[Formula: see text]Chemically inert solvents can affect the rate of chain initiation and the rate of chain propagation but they do not appear to affect the rate of chain termination.
THE PREPARATION OF A TRIVINYL CARBONIUM ION
Authors: Sorensen T. S.
Published: May 2006

The preparation of a stable trivinyl carbonium ion is described. A detailed evaluation and comparison of the n.m.r. spectrum of this ion with other stable carbonium ions, coupled with the use of ultraviolet spectroscopy, is used for the structure proof. The synthesis of the necessary tetraene precurser and the cyclization reactions of the above ion are also described. Comparisons of the cyclization rate of various stable carbonium ions are given and an attempt is made to evaluate the resonance stability of the trivinyl carbonium ion.
CORRELATION OF ETHYLENIC PROTON COUPLING CONSTANTS WITH THE ELECTRONEGATIVITY OF SUBSTITUENTS INTERPRETATION OF THE DEVIATIONS OF BROMO AND IODO SUBSTITUENTS
Authors: Hruska F. , Kotowycz G. , Schaefer T.
Published: May 2006

It is shown that for the geminal, cis and trans proton coupling constants in vinyl bromide and vinyl iodide there exist significant deviations from an inverse linear relationship between coupling constants and the electronegativity of the substituent in monosubstituted ethylenes. By an adaptation of the box model of Juan and Gutowsky to the 13C—H coupling constants in the system CH2 = CHX, it is shown that there are related anomalies in the 13C—H coupling constants in vinyl bromide and vinyl iodide. A comparison of the three types of 13C—H coupling constants in some vinyl compounds suggests that there may be an interaction between the substituent and the C—H bond which affects the coupling constant but not the s-character of the carbon orbital in the bond.
ULTRAVIOLET STUDY OF THE IONIZATION OF BISULFATE ION
Authors: Edward J. T. , Wang I. C.
Published: May 2006

Studies of the ultraviolet absorption of dilute aqueous solutions of lithium, sodium, potassium, and ammonium sulfates show that the concentration of sulfate ion in the presence of univalent cations can be determined from the optical density of the solution at 190 mμ. The concentrations of sulfate ion thus determined in dilute solutions of sulfuric acid are in agreement with values reported previously from Raman spectral, conductivity, and other studies, which indicate a dissociation constant K2 = 0.01 for the second stage in the ionization of sulfuric acid.
SPECTROSCOPIC STUDIES OF ALCOHOLS: V. INTRAMOLECULAR HYDROGEN BONDS IN 2-CYANOETHANOL AND IN SOME NITROALCOHOLS
Authors: Krueger P. J. , Mettee H. D.
Published: May 2006

The enthalpy difference between the trans and the intramolecularly hydrogen bonded gauche conformation of 2-cyanoethanol in dilute CCl4 solution is shown to be −0.14 ± 0.03 kcal/mole from the temperature dependence of the fundamental OH stretching bands. At higher concentrations cyclic dimers with double OH … O bonds form. The enthalpy change on dimerization is −6.1 ± 0.3 kcal/mole. A small percentage of dimers with acylic OH … O bonds are also present, but these are thermodynamically less stable than the cyclic dimers.Intramolecular hydrogen bonds are found between OH and NO2 groups in some 2-nitro-alcohols, leading to stabilization of the gauche form with respect to the trans form. For 2-nitroethanol the trans conformer is in equilibrium with two intramolecularly hydrogen bonded conformers (ΔH = −0.40 ± 0.10 and −0.71 ± 0.09 kcal/mole respectively). 2,2-Dinitro-propanol and 2-methyl-2-nitro-1,3-propanediol show complex νOH bands due to trans and intramolecularly hydrogen bonded gauche conformers. 2,2,2-Trinitroethanol has a relatively narrow symmetrical OH peak at temperatures up to 55 °C which is assigned to the exclusively populated intramolecularly hydrogen bonded conformation.
FOR SUBSTITUTED ALDEHYDES
Authors: Hammaker R. M.
Published: May 2006

not available
ALIPHATIC CHEMISTRY OF FLUORENE PART X. 2-PHENYLINDOLENINE-3-SPIRO-9′-FLUORENE
Authors: Bavin P. M. G.
Published: May 2006

not available
THE ACTION OF FENTON'S REAGENT ON CYCLOPROPYLCARBINOL
Authors: Lee C. C. , Cessna A. J. , Frost Moira K.
Published: May 2006

not available
TERPENOIDS: XII. THE STRUCTURE OF CHAPARRIN
Authors: Davidson T. A. , Hollands T. R. , Mayo P. De , Nisbet M.
Published: May 2006

Chaparrin, the bitter principle from Castela nicholsonii may be dehydrated in two stages to give the partially aromatized substance chaparrol. By further stepwise degradation the latter has been converted to the dihydrophenanthrene (XIII) which allows the assignment of structures XVII and I to chaparrol and chaparrin respectively.
SPECTROSCOPIC STUDIES OF THE REVERSIBLE REACTION BETWEEN 2,2-DIPHENYL-1-PICRYLHYDRAZYL AND 2,4,6-TRI-t-BUTYLPHENOL
Authors: Ayscough P. B. , Russell K. E.
Published: May 2006

The reaction between 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,4,6-tri-t-butylphenol in benzene solution has been studied by optical and electron spin resonance methods. In the absence of oxygen, equilibrium is reached with the products 2,2-diphenyl-1-picrylhydrazine and the tri-t-butylphenoxy radical. The equilibrium constant for the reaction is 0.10 ± 0.03 at 20 °C and from its variation with temperature the heat of reaction is estimated to be 1.6 ± 0.3 kcal/mole. The entropy change in the reaction is small.The rate constants for the forward reactions with tri-t-butylphenol and deuterated tri-t-butylphenol are 0.12 ± 0.02 1/(mole s) and 0.010 ± 0.002 1/(mole s) respectively at 20 °C. The corresponding activation energies are 6.5 ± 0.8 kcal/mole and 7.7 ± 0.7 kcal/mole. The rate constant for the reverse reaction is approximately 2 1/(mole s) at 20 °C and the activation energy is 4.8 ± 1 kcal/mole.
A LINEAR CORRELATION OF PROTON CHEMICAL SHIFTS IN SOME ALKYL CHLORIDES AND HYDROCARBONS WITH THE OCCUPATION NUMBER OF THE HYDROGEN ORBITALS
Authors: Hruska F. , Kotowycz G. , Schaefer T.
Published: May 2006

A linear correlation exists between the proton shifts of some alkyl chlorides and some hydrocarbons and the occupation numbers of the hydrogen 1s orbitals in the C—H bonds. The occupation numbers are those given by the self-consistent group orbital and bond electronegativity method. The application of this correlation to the prediction of starting values for occupation numbers, to the derivation of bond anisotropies in ethylene and acetylene, and to the prediction of hydrogen-bonded shifts of C—H protons is discussed.
THE RATIOS OF STEPWISE STABILITY CONSTANTS: III. THE RARE-EARTH α-HYDROXYMONOCARBOXYLATES
Authors: Manning P. G.
Published: May 2006

The magnitudes of stepwise stability constant ratios indicate that the α-hydroxymonocarboxylic acids, in their association reactions with the rare-earth cations, function as monodentate ligands.
ESSENTIAL OILS AND THEIR CONSTITUENTS: XXIX. THE ESSENTIAL OIL OF MARIHUANA: COMPOSITION OF GENUINE INDIAN CANNABIS SATIVA L.
Authors: Nigam M. C. , Handa K. L. , Nigam I. C. , Levi Leo
Published: May 2006

The essential oil obtained by hydrodistillation of freshly harvested Indian Cannabis sativa L. was found to contain the following constituents that have not previously been reported: α-pinene, camphene, β-pinene, α-terpinene, β-phellandrene, γ-terpinene, linalool, trans-linalool oxide, sabinene hydrate, α-bergamotene, terpinene-4-ol, β-farnesene, α-terpineol, α-selinene, curcumene, and caryophyllene oxide. The presence of trace amounts of two alcohols and of an α,β-unsaturated ketone, for which gas chromatographic and spectral characteristics are recorded, was also detected.
REARRANGEMENT STUDIES WITH 14C: XXIV. SOLVOLYSES OF 2-(α-NAPHTHYL)-1-14C-ETHYL p-TOLUENESULFONATE
Authors: Lee C. C. , Forman A. G.
Published: May 2006

Acetolysis and formolysis of 2-(α-naphthyl)-1-14C-ethyl p-toluenesulfonate (I-OTs) were interrupted after 50% completion and the products, 2-(α-naphthyl)ethyl acetate and formate (I-OAc and I-OCHO), and the "unreacted" I-OTs were recovered. Rearrangements of the 14C-label from C-1 to C-2 were found to be about 46% and 50%, respectively, in the I-OAc and I-OCHO. A similar rearrangement amounting to about 38% was observed in the I-OTs recovered from the acetolysis, while the I-OTs recovered from formolysis showed less than 1% 14C rearrangement. Titrimetric rates for these reactions were determined and compared with known rates of solvolyses of 2-phenylethyl and ethyl p-toluenesulfonates. Small rate enhancements were indicated. The mechanistic implications of these results in relation to current carbonium ion theory are discussed.
THE ELECTRON SPIN RESONANCE SPECTRA OF DINITRONAPHTHALENE ANION RADICALS
Authors: Fischer P. H. H. , McDowell C. A.
Published: May 2006

The radical anions of 1,4-dinitronaphthalene, 1,5-dinitronaphthalene, and 1,8-dinitronaphthalene have been generated by electrolytic means, and their e.s.r. spectra recorded. The spectra consist of 61, 111, and 85 lines respectively, and can be analyzed in terms of one nitrogen and three proton coupling constants, consistent with the full symmetry of the species giving rise to them. These constants are, for 1,4-dinitronaphthalene: aN = 0.97 G, aH2 = 1.69 G, aH5 = 0.53 G, and aH6 = 0.41 G; for 1,5-dinitronaphthalene: aN = 2.30 G, aH2 = 2.42 G, aH3 = 0.44 G, and aH4 = 2.82 G; for 1,8-dinitronaphthalene: aN = 3.03 G, aH2 = 3.63 G, aH3 = 0.95 G, and aH4 = 3.73 G. Whereas the nitrogen coupling constants can be unambiguously assigned, this, in the absence of deuteration studies say, is not the case for the three sets of equivalent protons. As an aid in the assignment of proton coupling constants, Hückel LCAO calculations and simplified SCFMO calculations by the method of McLachlan have been performed. The first mentioned of the above proton constants could thus be assigned with reasonable certainty, the remaining two aHi remain ambiguous.
PREPARATION OF α-FLUORO-γ-AMINOACIDS
Authors: Buchanan R. L. , Pattison F. L. M.
Published: May 2006

not available
Three-dimensional imaging and morphometric analysis of alveolar tissue from microfocal X-ray-computed tomography
Authors: Litzlbauer Horst Detlef , Neuhaeuser Christoph , Moell Alexander , Greschus Susanne , Breithecker Andreas , Franke Folker Ernst , Kummer Wolfgang , Rau Wigbert Stephan
Published: May 2006

We evaluated microfocal X-ray-computed tomography (micro-CT) as a method to visualize lung architecture two and three dimensionally and to obtain morphometric data. Inflated porcine lungs were fixed by formaldehyde ventilation. Tissue samples (8-mm diameter, 10-mm height) were stained with osmium tetroxide, and 400 projection images (1,024 × 1,024 pixel) were obtained. Continuous isometric micro-CT scans (voxel size 9 μm) were acquired to reconstruct two- and three-dimensional images. Tissue samples were sectioned (8-μm thickness) for histological analysis. Alveolar surface density and mean linear intercept were assessed by stereology-based morphometry in micro-CT scans and corresponding histological sections. Furthermore, stereology-based morphometry was compared with morphometric semi-automated micro-CT analysis within the same micro-CT scan. Agreement of methods was assessed by regression and Bland-Altman analysis. Comparing histology with micro-CT, alveolar surface densities (35.4 ± 2.4 vs. 33.4 ± 1.9/mm, P < 0.05) showed a correlation ( r = 0.72; P = 0.018) with an agreement of 2 ± 1.6/mm; the mean linear intercept (135.7 ± 14.5 vs. 135.8 ± 15 μm) correlated well ( r = 0.97; P < 0.0001) with an agreement of −0.1 ± 3.4 μm. Semi-automated micro-CT analysis resulted in smaller alveolar surface densities (33.4 ± 1.9 vs. 30.5 ± 1/mm; P < 0.01) with a correlation ( r = 0.70; P = 0.023) and agreement of 2.9 ± 1.4/mm. Non-destructive micro-CT scanning offers the advantage to visualize the spatial tissue architecture of small lung samples two and three dimensionally.
Validation of a Generalized Transfer Function to Noninvasively Derive Central Blood Pressure During Exercise
Authors: Sharman James E. , Lim Richard , Qasem Ahmad M. , Coombes Jeff S. , Burgess Malcolm I. , Franco Jeff , Garrahy Paul , Wilkinson Ian B. , Marwick Thomas H.
Published: May 2006

Exercise brachial blood pressure (BP) predicts mortality, but because of wave reflection, central (ascending aortic) pressure differs from brachial pressure. Exercise central BP may be clinically important, and a noninvasive means to derive it would be useful. The purpose of this study was to test the validity of a noninvasive technique to derive exercise central BP. Ascending aortic pressure waveforms were recorded using a micromanometer-tipped 6F Millar catheter in 30 patients (56±9 years; 21 men) undergoing diagnostic coronary angiography. Simultaneous recordings of the derived central pressure waveform were acquired using servocontrolled radial tonometry at rest and during supine cycling. Pulse wave analysis of the direct and derived pressure signals was performed offline (SphygmoCor 7.01). From rest to exercise, mean arterial pressure and heart rate were increased by 20±10 mm Hg and 15±7 bpm, respectively, and central systolic BP ranged from 77 to 229 mm Hg. There was good agreement and high correlation between invasive and noninvasive techniques with a mean difference (±SD) for central systolic BP of −1.3±3.2 mm Hg at rest and −4.7±3.3 mm Hg at peak exercise (for both
r
=0.995;
P
<0.001). Conversely, systolic BP was significantly higher peripherally than centrally at rest (155±33 versus 138±32 mm Hg; mean difference, −16.3±9.4 mm Hg) and during exercise (180±34 versus 164±33 mm Hg; mean difference, −15.5±10.4 mm Hg; for both
P
<0.001). True myocardial afterload is not reliably estimated by peripheral systolic BP. Radial tonometry and pulse wave analysis is an accurate technique for the noninvasive determination of central BP at rest and during exercise.
Creation of Engineered Cardiac Tissue In Vitro From Mouse Embryonic Stem Cells
Authors: Guo Xi-Min , Zhao Yun-Shan , Chang Hai-Xia , Wang Chang-Yong , E Ling-Ling , Zhang Xiao-Ai , Duan Cui-Mi , Dong Ling-Zhi , Jiang Hong , Li Jing , Song Ying , Yang Xiangzhong (Jerry)
Published: May 2006

Background—

Embryonic stem (ES) cells can terminally differentiate into all types of somatic cells and are considered a promising source of seed cells for tissue engineering. However, despite recent progress in in vitro differentiation and in vivo transplantation methodologies of ES cells, to date, no one has succeeded in using ES cells in tissue engineering for generation of somatic tissues in vitro for potential transplantation therapy.

Methods and Results—

ES-D3 cells were cultured in a slow-turning lateral vessel for mass production of embryoid bodies. The embryoid bodies were then induced to differentiate into cardiomyocytes in a medium supplemented with 1% ascorbic acid. The ES cell–derived cardiomyocytes were then enriched by Percoll gradient centrifugation. The enriched cardiomyocytes were mixed with liquid type I collagen supplemented with Matrigel to construct engineered cardiac tissue (ECT). After in vitro stretching for 7 days, the ECT can beat synchronously and respond to physical and pharmaceutical stimulation. Histological, immunohistochemical, and transmission electron microscopic studies further indicate that the ECTs both structurally and functionally resemble neonatal native cardiac muscle. Markers related to undifferentiated ES cell contamination were not found in reverse transcriptase–polymerase chain reaction analysis of the Percoll-enriched cardiomyocytes. No teratoma formation was observed in the ECTs implanted subcutaneously in nude mice for 4 weeks.

Conclusions—

ES cells can be used as a source of seed cells for cardiac tissue engineering. Additional work remains to demonstrate engraftment of the engineered heart tissue in the case of cardiac defects and its functional integrity within the host’s remaining healthy cardiac tissue.
Outcome of Watchful Waiting in Asymptomatic Severe Mitral Regurgitation
Authors: Rosenhek Raphael , Rader Florian , Klaar Ursula , Gabriel Harald , Krejc Marcel , Kalbeck Daniel , Schemper Michael , Maurer Gerald , Baumgartner Helmut
Published: May 2006

Background—

The management of asymptomatic severe mitral regurgitation remains controversial. The aim of this study was to evaluate the outcome of a watchful waiting strategy in which patients are referred to surgery when symptoms occur or when asymptomatic patients develop left ventricular (LV) enlargement, LV dysfunction, pulmonary hypertension, or recurrent atrial fibrillation.

Methods and Results—

A total of 132 consecutive asymptomatic patients (age 55±15 years, 49 female) with severe degenerative mitral regurgitation (flail leaflet or valve prolapse) were prospectively followed up for 62±26 months. Patients underwent serial clinical and echocardiographic examinations and were referred for surgery when the criteria mentioned above were fulfilled. Overall survival was not statistically different from expected survival either in the total group or in the subgroup of patients with flail leaflet. Eight deaths were observed. Thirty-eight patients developed criteria for surgery (symptoms, 24; LV criteria, 9; pulmonary hypertension or atrial fibrillation, 5). Survival free of any indication for surgery was 92±2% at 2 years, 78±4% at 4 years, 65±5% at 6 years, and 55±6% at 8 years. Patients with flail leaflet tended to develop criteria for surgery slightly but not significantly earlier. There was no operative mortality. Postoperative outcome was good with regard to survival, symptomatic status, and postoperative LV function.

Conclusions—

Asymptomatic patients with severe degenerative mitral regurgitation can be safely followed up until either symptoms occur or currently recommended cutoff values for LV size, LV function, or pulmonary hypertension are reached. This management strategy is associated with good perioperative and postoperative outcome but requires careful follow-up.
Abortion Legislation and the Future of the 'Counseling Model'
Authors: Gevers Sjef
Published: May 2006

This article aims at further reflection on the 'counseling model'. It is based on the recent evaluation of the Dutch abortion act. How has this model worked in the Netherlands? What can be learned from that experience about its weak and strong sides, as well as about its suitability for the future, taking into account relevant medical and societal developments? In doing so, the article first elaborates on three models relating them also to the present legal situation in a number of European countries. A description of the Dutch act and a report on the results of the evaluation study which was carried out in the years 2004–2005 is given. Finally, on the basis of these findings, the author discusses the merits of the 'counseling model', also with a view to the future.
Components of the antigen processing and presentation pathway revealed by gene expression microarray analysis following B cell antigen receptor (BCR) stimulation
Authors: Lee Jamie A , Sinkovits Robert S , Mock Dennis , Rab Eva L , Cai Jennifer , Yang Peng , Saunders Brian , Hsueh Robert C , Choi Sangdun , Subramaniam Shankar , Scheuermann Richard H ,   in collaboration with the Alliance for Cellular Signaling
Published: May 2006

Background

Activation of naïve B lymphocytes by extracellular ligands, e.g. antigen, lipopolysaccharide (LPS) and CD40 ligand, induces a combination of common and ligand-specific phenotypic changes through complex signal transduction pathways. For example, although all three of these ligands induce proliferation, only stimulation through the B cell antigen receptor (BCR) induces apoptosis in resting splenic B cells. In order to define the common and unique biological responses to ligand stimulation, we compared the gene expression changes induced in normal primary B cells by a panel of ligands using cDNA microarrays and a statistical approach, CLASSIFI (ClusterAssignmentfor BiologicalInference), which identifies significant co-clustering of genes with similar Gene Ontology™ annotation.

Results

CLASSIFI analysis revealed an overrepresentation of genes involved in ion and vesicle transport, including multiple components of the proton pump, in the BCR-specific gene cluster, suggesting that activation of antigen processing and presentation pathways is a major biological response to antigen receptor stimulation. Proton pump components that were not included in the initial microarray data set were also upregulated in response to BCR stimulation in follow up experiments. MHC Class II expression was found to be maintained specifically in response to BCR stimulation. Furthermore, ligand-specific internalization of the BCR, a first step in B cell antigen processing and presentation, was demonstrated.

Conclusion

These observations provide experimental validation of the computational approach implemented in CLASSIFI, demonstrating that CLASSIFI-based gene expression cluster analysis is an effective data mining tool to identify biological processes that correlate with the experimental conditional variables. Furthermore, this analysis has identified at least thirty-eight candidate components of the B cell antigen processing and presentation pathway and sets the stage for future studies focused on a better understanding of the components involved in and unique to B cell antigen processing and presentation.
Correlation between CD105 expression and postoperative recurrence and metastasis of hepatocellular carcinoma
Authors: Yang Lian-yue , Lu Wei-qun , Huang Geng-wen , Wang Wei
Published: May 2006

Background

Angiogenesis is one of the mechanisms most critical to the postoperative recurrence and metastasis of hepatocellular carcinoma (HCC). Thus, finding the molecular markers associated with angiogenesis may help identify patients at increased risk for recurrence and metastasis of HCC. This study was designed to investigate whether CD105 or CD34 could serve as a valid prognostic marker in patients with HCC by determining if there is a correlation between CD105 or CD34 expression and postoperative recurrence or metastasis.

Methods

Immunohistochemical staining for the CD105, CD34 and vascular endothelial growth factor (VEGF) antibodies was performed in 113 HCC tissue specimens containing paracarcinomatous tissue and in 14 normal liver tissue specimens. The quantitation of microvessels identified by anti-CD105 and anti-CD34 monoclonal antibodies and the semiquantitation of VEGF expression identified by anti-VEGF monoclonal antibody were analyzed in conjunction with the clinicopathological characteristics of the HCC and any available follow-up information about the patients from whom the specimens were obtained.

Results

CD105 was not expressed in the vascular endothelial cells of any normal liver tissue or paracarcinomatous liver tissue but was expressed in the vascular endothelial cells of all HCC tissue. In contrast, CD34 was expressed in the vascular endothelial cells of normal liver tissue, paracarcinomatous tissue, and HCC tissue in the following proportions of specimens: 86.7%, 93.8%, and 100%, respectively. The microvascular densities (MVDs) of HCC determined by using an anti-CD105 mAb (CD105-MVD) and an anti-CD34 mAb (CD34-MVD), were 71.7 ± 8.3 (SD) and 106.3 ± 10.4 (SD), respectively. There was a significant correlation between CD105-MVD and CD34-MVD (r = 0.248, P = 0.021). Although CD34-MVD was significantly correlated with VEGF expression (r = 0.243, P = 0.024), CD105-MVD was more closely correlated (r = 0.300, P= 0.005). The correlation between microscopic venous invasion and CD105-MVD, but not CD34-MVD, was also statistically significant (r = 0.254, P = 0.018). Univariate analysis showed that CD105-MVD was significantly correlated with the 2-year overall survival rate (P = 0.014); CD34-MVD was not (P = 0.601). Multivariate analysis confirmed that CD105-MVD was an independent prognostic factor and that CD34-MVD was not.

Conclusion

The anti-CD105 mAb is an ideal instrument to quantify new microvessels in HCC as compared with anti-CD34 mAb. CD105-MVD as compared with CD34-MVD is relevant a significant and independent prognostic indicator for recurrence and metastasis in HCC patients.
Allelic drop-out may occur with a primer binding site polymorphism for the commonly used RFLP assay for the -1131T>C polymorphism of the Apolipoprotein AV gene
Authors: Ward Kirsten J , Ellard Sian , Yajnik Chittaranjan S , Frayling Timothy M , Hattersley Andrew T , Venigalla Prathyusha NS , Chandak Giriraj R
Published: May 2006

Apolipoprotein AV (ApoAV) gene variant, -1131T>C, is associated with increased triglyceride concentrations in all ethnic groups studied. An MseI based RFLP analysis is the most commonly used method for genotyping this SNP. We genotyped a large cohort comprising 1185 Asian Indians and 173 UK Caucasians for -1131T>C using an ARMS-PCR based tetra-primer method. For quality control, we re-genotyped approximately 10% random samples from this cohort utilizing the MseI RFLP, which showed a 2.9% (3/102) genotyping error rate between the two methods. To investigate further, we sequenced the 900 bp region around the -1131T>C polymorphism in 25 Asian Indians and 15 UK Caucasians and found a number of polymorphisms including the -987C>T polymorphism. Further analysis of the -987C>T SNP showed a higher rare allele frequency of 0.23 in Asian Indians (n = 158) compared to 0.09 in the UK Caucasians (n = 157). This SNP is located 4 bp from the 3' end of the RFLP forward primer and is in weak linkage disequilibrium with -1131T>C variant (r2 = 0.084 and D' = 1). Repeated RFLP analysis of seven subjects heterozygous for -987C>T (seven times), showed discordant results with the sequence at -1131T>C SNP nearly one third (15/49) of the time. We conclude that presence of -987C>T polymorphism in the forward primer of the MseI RFLP assay may lead to allelic drop-out and generate unforeseen errors in genotyping the -1131T>C polymorphism. Our results also emphasise the need for careful quality control in all molecular genetic studies, particularly while transferring genotyping methods between various ethnic groups.
Photo-induced Ionic Conductivity Switching in Polymer/Photochromic Liquid Crystal Composite Films Containing Lithium/Crown Ether Complex
Authors: Kimura Keiichi , Suzuki Tatsuya , Yokoyama Masaaki
Published: May 2006

Thin composite films consisting of poly(vinyl chloride), azobenzene liquid crystal, lithium ion/12-crown-4 complex exhibited reversible photo-induced switching of ionic conductivity based on the photochromic phase transition of the azobenzene derivative. The ionic conductivities increased by more than two orders of magnitude by UV light and then reverted to the initial state by visible light at ambient temperature.
Mechanism for Electron-Transfer Induced Isomerization of Stilbene as Studied by Magnetic Field Effects
Authors: Kuriyama Yasunao , Arai Tatsuo , Sakuragi Hirochika , Tokumaru Katsumi
Published: May 2006

External magnetic field effects and laser flash photolysis were applied to elucidating the mechanism of dicyanoanthracene-sensitized isomerization of stilbene in acetonitrile, indicating that the stilbene cation radical is a key intermediate for isomerization. Sensitizer dependence of the isomerization efficiency is discussed in terms of the rate of back electron transfer in singlet radical pairs.
Stepwise Reactions of Dimethylsilyl Acetylenes with Octacarbonyldicobalt
Authors: Kotani Sonae , Matsumoto Toshihiro , Yamaguchi Hidemasa , Shiina Kyo , Sonogashira Kenkichi
Published: May 2006

Treatment of bis(dimethylsilyl)acetylene 1 with more than two molar amount of octacarbonyldicobalt in cyclohexane gave the complex [(CO)4CoSiMe2C≡C–SiMe2Co(CO)4]Co2(CO)6, while treatment of 1 with one or 1.5 molar amount of octacarbonyldicobalt produced the complexes [HSiMe2C≡CSiMe2H]Co2(CO)6 and [HSiMe2C≡CSiMe2Co(CO)4]Co2(CO)6, respectively. The reactions of dimethyl(phenylethynyl)silane and its homologs with Co2(CO)8 were also investigated.
Efficient Asymmetric Hydrogenations of (Z)-2-Acetamidoacrylic Acid Derivatives with the Cationic Rhodium Complex of (2S,4S)-MOD-BPPM
Authors: Takahashi Hisashi , Achiwa Kazuo
Published: May 2006

The preparation of (2S,4S)-MOD-BPPM ((2S,4S)-N-(t-butoxycarbonyl)-4-[[bis(4′-methoxy-3′,5′-dimethylphenyl)]phosphino]-2-[[[bis(4′-methoxy-3′,5′-dimethylphenyl)]phosphino]methyl]pyrrolidine) and its application to highly effective asymmetric hydrogenations of (Z)-2-acetamidoacrylic acid derivatives are described.
Origin of Multiline ESR Signal Observed for Manganese(III) Complexes with N-Alkyl-N,N-bis(benzimidazol-2-ylmethyl)amine
Authors: Nishida Yuzo , Haga Sachiko , Tokii Tadashi
Published: May 2006

We have observed that some manganese(III) complexes with N-alkyl-N,N-bis(benzimidazol-2-ylmethyl)amine exhibit a multiline ESR signal around g = 2 in the frozen state(below 77 K), and this has been attributed to the superposition of at least three components with 11 lines due to the dimeric manganese(III) pair.
Photoinduced Selective Synthesis of Ethylene Glycol from Methanol in the Presence of Hydrogen Peroxide
Authors: Shimizu Yuichi , Sugimoto Shun’ichi , Suzuki Nobutake
Published: May 2006

Ethylene glycol was selectively synthesized by UV irradiation of the nitrogen-saturated methanol containing hydrogen peroxide. The concentration of ethylene glycol and the selectivity were affected markedly by a H2O2 feeding rate.
Synthesis of 1,2,4-Tri-O-acetyl-5-deoxy-5-[(R,S)-ethyl- and phenylphosphino]-3-O-methyl-α,β-d-xylopyranoses and an Efficient Conversion to the Corresponding 5-(Phosphinothioyl)-d-xylopyranoses
Authors: Yamamoto Hiroshi , Hanaya Tadashi , Shigetoh Nobuyuki , Kawamoto Heizan , Inokawa Saburo
Published: May 2006

Reduction of 1,2,4-tri-O-acetyl-5-deoxy-5-[(R,S)-ethyl- and phenylphosphinyl]-α,β-d-xylopyranoses with trichlorosilane in benzene in the presence of triethylamine smoothly afforded the corresponding title 5-phosphino-d-xylopyranoses (10–13a,b) without causing epimerization at C-1 and ring-P. Treatment of 10–13 with sulfur efficiently provided the corresponding (phosphinothioyl)-in-ring sugar analogues.
The 1H NMR Spectral Detection and Kinetic Analysis of the Conformational Change of 4,4,5,5- and 6,6,7,7-Tetramethoxycycloheptadienones
Authors: Mori Akira , Kubota Tadahiko , Takeshita Hitoshi
Published: May 2006

The variable temperature 1H NMR measurements of 4,4,5,5- and 6,6,7,7-tetramethoxycycloheptadienones disclosed an existence of the bond-twisting conformers. The complete line shape analysis by the simulation method gave the activation parameters of the interconversion barrier.
Water Sensitivity of a [Fe4S4(SR)4]1− Cluster and Its Stabilization
Authors: Ohno Ryotaro , Ueyama Norikazu , Nakamura Akira
Published: May 2006

The electrochemical studies of 4Fe–4S high potential iron–sulfur protein model complexes revealed the high sensitivity of [Fe4S4(SR)4]1− cluster to water. Such sensitivity was lowered by hydrophobic groups of thiolate ligands in close proximity to a cluster.
Spontaneous Formation of a Network of Helical Strands from Ditetradecanoyl- and Didodecanoyl-5′-phosphatidylcytidine
Authors: Yanagawa Hiroshi , Ogawa Yoko , Furuta Hiroyuki , Tsuno Katsushige
Published: May 2006

Phospholipid-nucleoside conjugates containing two tetradecanoyl or dodecanoyl groups and a cytidyl group spontaneously assemble to form a network structure of helical strands in aqueous solution. The network structures consisted of a double helical strand and two single helical strands. The network structures were gradually converted into linearly extended double helical strands.
Selective Determination of Vanadium in River Water by High-performance Liquid Chromatography
Authors: Uehara Nobuo , Morimoto Kazuhiro , Shimizu Tokuo , Shijo Yoshio
Published: May 2006

A method for the selective determination of vanadium in river water using high-performance liquid chromatography after preconcentration with a convenient evaporator was investigated. 2-(5-Bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol was used as a precolumn chelating reagent for V(V) in the presence of CyDTA. The detection limit of the proposed method was 35 ng 1−1 after the 25 fold enrichment procedure.
Facile Synthesis of Chloro-substituted Aromatic Ethers by Use of Benzyltrimethylammonium Tetrachloroiodate
Authors: Kajigaeshi Shoji , Shinmasu Youichi , Fujisaki Shizuo , Kakinami Takaaki
Published: May 2006

The reaction of aromatic ethers with a calculated amount of benzyltrimethylammonium tetrachloroiodate in acetic acid (or dichloromethane) under mild conditions gave, selectively, the objective chloro-substituted aromatic ethers in good yields.
Syntheses of 3-Cyano-2H-thiin S-Imides and Ylides and Their Base-Promoted Rearrangement
Authors: Motoki Shinichi , Takahashi Narushi , Eguchi Kazuhiro , Saito Takao
Published: May 2006

The reaction of 3-cyano-2H-thiin derivatives with chloramine salt or diazomalonate gave the corresponding sulfilimines or sulfonium ylides and dihydrothiepin derivatives. These products rearranged by the action of DBU eventually to afford pyridine derivatives or benzofuran and benzothiophene derivatives.
Studies of cis-trans Isomerization of Stilbene Anion Radicals by Means of a Flow-Electrolysis ESR Method
Authors: Nozaki Koichi , Naito Akira , Ho Tong-Ing , Hatano Hiroyuki , Okazaki Satoshi
Published: May 2006

Mechanism and kinetics of the cis-trans isomerization of stilbene anion radicals was revealed with a flow-electrolysis ESR method in N,N-dimethylformamide.
Substituent Effect on the Gas Phase Basicity of Pyridine N-Oxide
Authors: Mishima Masaaki , Terasaki Takahiro , Fujio Mizue , Tsuno Yuho , Takai Yoshio , Sawada Masami
Published: May 2006

Gas phase basicities of pyridine N-oxides were determined by means of a pulsed ICR spectrometer. It has been shown that the resonance demand for π-acceptors is intrinsically greater in pyridine N-oxide than in pyridine and that the attenuation of substituent effect owing to solvation stabilization is more significant in the former system.
Observation of the Ultrafine Platinum Particles over an Active Carbon Catalyst Support with a High-Resolution Scanning Electron Microscope
Authors: Yahikozawa Kiyochika , Kaneko Fuminori , Tsutsui Tsuyoshi , Nakagawa Mine , Yamada Mitsuhiko , Takasu Yoshio
Published: May 2006

Ultrafine platinum particles larger than ca. 2 nm in diameter over a powdery active carbon catalyst support have clearly been observed with a high-resolution scanning electron microscope.
α-Methoxy-α-trifluoromethylpropionic Acid (MTPr). A New Chiral Derivatizing Reagent for GC Separation of Enantiomeric Amino Acids
Authors: Yasuhara Fujiko , Takeda Masayuki , Ochiai Yoshiro , Miyano Sotaro , Yamaguchi Shozo
Published: May 2006

A title homochiral acid has been synthesized and shown to be an efficient chiral derivatizing reagent for capillary gas chromatographic separation of enantiomeric amino acids at considerably low column temperature.
The Synthesis of a [13][15]Fulvalene Derivative
Authors: Higuchi Hiroyuki , Kitamura Keiko , Ojima Juro , Yamamoto Koji , Yamamoto Gaku
Published: May 2006

The first example of fuluvalene derivative containing two monocyclic large-membered rings, 1-(5,10-dimethyl-6,7,8,9-tetradehydrocyclotridecen-1-ylidene)-7,12-dimethyl-8,9,10,11-tetradehydrocyclopentadecene, has been synthesized. Examination of 1H and 13C NMR spectra indicates that the tridecapentadecafulvalene derivative shows no ring current effect but polyolefinic character.
Dehalogenation of α-Halo Carbonyl Compounds by a New Efficient Reagent, Triphenylphosphonium Iodide
Authors: Kamiya Naoshi , Tanmatu Hiroshi , Ishii Yasutaka
Published: May 2006

Triphenylphosphonium iodide, Ph3PHI, was found to be an efficient reagent for the dehalogenation of α-halo carbonyl compounds. α-Halo esters, which were difficult to be reduced with Me3SiCl/Nal reagent, was smoothly debrominated by Ph3PHI. Treatment of α-halocarbonyl compounds with Ph3PDI produced the corresponding α-deuterated compounds.
Stereocontrol in the Michael Reaction of Dimethyl Malonate with Alkyl 2-(1-Hydroxyalkyl)propenoates
Authors: Lawrence Ronnie M , Perlmutter Patrick
Published: May 2006

In this paper we show that the stabilized carbanion dimethyl malonate adds to alkyl 2-(1-hydroxyalkyl)propenoates under basic conditions. Side reactions, such as lactonization or elimination, may be reduced and/or completely avoided by the use of phase transfer catalysis. The high stereoselectivity associated with the additions discussed here was found to be under thermodynamic control.
Emissive Triplex Formation in a Methylene-Bridged A-D-D′ System. Intramolecular Long-Range Electron Transfer
Authors: Masaki Yasuhiro , Uehara Yoshikazu , Yanagida Shozo , Pac Chyongjin
Published: May 2006

Methylene-bridged trichromophoric A-D-D′ reveals only triplex emission at longer wavelength than bichromophoric A-D′ and A-D, providing a model for long-range emissive and nonemissive electron transfer between A and D′ through π spacer D.
Participation of a Chain Mechanism in Efficient Monomerization of Dimethylthymine Cyclobutane Dimer Photosensitized by a Flavin in the Presence of Perchloric Acid
Authors: Masaki Yasuhiro , Miyake Kunihito , Yanagida Shozo , Pac Chyongjin
Published: May 2006

The monomerization of cis-cisoid cyclobutane dimer of 1,3-dimethylthymine is photosensitized by riboflavin tetraacetate with quantum yields of larger than unity in Ar-purged solution in the presence of perchloric acid, whereas the limiting quantum yields for degassed and aerated solutions are unity.
NO2 Sensitive Ga-doped ZnO Thin Film
Authors: Matsushima Shigenori , Ikeda Daisuke , Kobayashi Kenkichiro , Okada Genji
Published: May 2006

The resistivity of a Ga-doped ZnO film in a NO2 atmosphere remarkably increases with decreasing the thickness of the film while that in air remains unchanged. A Ga-doped ZnO film with 75 nm in thickness shows high sensitivity and rapid response to NO2 at 400 °C.
Emission Spectra of p-Xylene Excited by Ar+ Ion Beam
Authors: Fukuzumi Takahiro , Miyachi Shigeki , Nakashima Keiji , Ogawa Teiichiro
Published: May 2006

Emission spectra of p-xylene were measured under ion-impact excitation. There were a weak band of the S1-S0 transition of p-xylene itself and several intense bands of excited fragment species. The spectra were similar to those excited by electron impact, but the band intensity of the parent molecule was much weaker under ion-impact excitation.
The Synthesis and Properties of Cyclopent[a]azulen-3(H)-one
Authors: Kitamori Yoichiro , Yasunami Masafumi , Hioki Takanori , Takase Kahei
Published: May 2006

A new tricyclic π-conjugated system, cyclopent[a]azulen-3(H)-one, was prepared by flash vacuum pyrolysis on the final step. All proton signals of this molecule were observed at higher magnetic resonance field than expected in terms of induced paramagnetic ring current in the periphery of this molecule.