Development and clinical application of high performance liquid chromatography for the simultaneous determination of plasma levels of theophylline and its metabolites without interference from caffeine

A high performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of plasma levels of theophylline and its metabolites without interference from caffeine or caffeine metabolites. The method is simple and of practical use because it is applicable even to plasma samples from patients who take caffeine-containing beverages. The method was also reproducible with a coefficient of variation of less than 5% for each analyte. The levels of theophylline, determined by HPLC, were validated by their high correlation to the levels obtained by fluorescence polarization immunoassay. HPLC was used to determine theophylline levels in patients with bronchial asthma. The data revealed that the ratio of 1,3-dimethyluric acid, the major metabolite of theophylline, to theophylline concentration in the plasma was within a narrow range in most patients (0.055 +/- 0.01, n = 66), regardless of the method of theophylline administration or the time of blood sampling. Conversely, this ratio was as low as 0.027 +/- 0.005 in the patient with a long plasma half-life of theophylline. These results suggest that it may be possible to predict the plasma half-life of theophylline for each patient from a single blood sample. This may be useful when planning theophylline administration, especially in patients with abnormal theophylline metabolism.     

Enantioselective intramolecular [2 + 2 + 2] cycloaddition of enediynes for the synthesis of chiral cyclohexa-1,3-dienes

The enantioselective intramolecular [2 + 2 + 2] cycloaddition of various enediynes, where two acetylenic moieties are connected by a trans-olefinic moiety, gave chiral tricyclic cyclohexa-1,3-dienes using Rh-H8-BINAP catalyst. In the case of carbon-atom-tethered enediynes, enantioselectivity was generally good-to-high regardless of the substituents on their alkyne termini. In contrast, with heteroatom-tethered enediynes, appropriate substituents were required to induce the oxidative coupling of alkyne and alkene moieties before that of two alkyne moieties, which would be important for highly enantioselective intramolecular cycloaddition.     

Nuclear-matter modification of decay widths in the phi-->e+e- and phi-->K+K- channels

The invariant mass spectra of phi-->K+K- are measured in 12 GeV p+A reactions in order to search for the in-medium modification of phi mesons. The observed K+K- spectra are well reproduced by the relativistic Breit-Wigner function with a combinatorial background shape in three betagamma regions between 1.0 and 3.5. The nuclear mass number dependence of the yields of the K+K- decay channel is compared to the simultaneously measured e+e- decay channel for carbon and copper targets. We parameterize the production yields as sigma(A)=sigma0Aalpha and obtain alphaphi-->K+K- -alphaphi-->e+e- to be 0.14+/-0.12. Limits are obtained for the partial decay widths of the phi mesons in nuclear matter.     

Determination of decamethylcyclopentasiloxane in river water and final effluent by headspace gas chromatography/mass spectrometry

A method is described for the analysis of decamethylcyclopentasiloxane (D(5)) in river water and treated waste water using headspace gas chromatography/mass spectrometry. Internal standard addition to samples and field blanks was carried out in the field to provide both a measure of recovery and to prevent any exposure of samples to laboratory air, which contained background levels of D(5). Measured levels of D(5) were typically in the range <10-29ngL(-1) in the River Great Ouse (UK) with slightly higher levels in the River Nene (UK). The measured concentration of D(5) in treated waste water varied between 31 and 400ngL(-1), depending on the type of treatment process employed.     

Effect of Substituents in Catechol Dye Sensitizers on Photovoltaic Performance of Type II Dye‐Sensitized Solar Cells

In order to provide a direction in molecular design of catechol (Cat) dyes for type II dye‐sensitized solar cells (DSSCs), the dye‐to‐TiO₂ charge‐transfer (DTCT) characteristics of Cat dyes with various substituents and their photovoltaic performance in DSSCs are investigated. The Cat dyes with electron‐donating or moderately electron‐withdrawing substituents exhibit a broad absorption band corresponding to DTCT upon binding to TiO₂ films, whereas those with strongly electron‐withdrawing substituents exhibit weak DTCT. This study indicates that the introduction of a moderately electron‐withdrawing substituent on the Cat moiety leads to not only an increase in the DTCT efficiency, but also the retardation of back electron transfer. This results in favorable conditions for the type II electron‐injection pathway from the ground state of the Cat dye to the conduction band of the TiO₂ electrode by the photoexcitation of DTCT bands.     

Aerosol-size distribution of radon daughter218Po in the accelerator tunnel air

Aerosol-size distributions of²¹⁸Po were determined for the accelerator tunnel air sampled during machine operation and for the basement air of a concrete building, where the number and the size distribution of non-radioactive aerosols are greatly different from each other. The²¹⁸Po distributions depended very much on the size distributions of ambient non-radioactive aerosols, and could be well explained by an attachment model of²¹⁸Po to ambient non-radioactive aerosols.     

Subunit analyses of a novel thermostable glucose dehydrogenase showing different temperature properties according to its quaternary structure

We previously reported a novel glucose dehydrogenase (GDH) showing two peaks in the optimum temperature for the reaction at around 45°C and at around 75°C. Each peak derived from hetero-oligomeric enzyme, constructed from two distinct peptides with an α-subunit (MWs 67,000) and β-subunit (MWs 43,000), and a single peptide enzyme containing an α-subunit alone. The function of the two subunits in the thermostable co-factor binding GDH was investigated. The results of spectroscopic analyses indicated that the α-subunit contained an unknown co-factor showing specific fluorescence spectra like pyrroloquinoline quinone (PQQ), and the β-subunit was cytochrome c. Moreover, the results of a urea denaturation and reconstitution experiment suggested that the dissociation of the hetero-oligomeric complex to a single peptide was reversible. The kinetic parameter analyses for glucose and the electron mediator also suggested that the β-subunit was responsible for electron transfer from the catalytic center of the α-subunit to the electron mediator.     

Biodegradation of formaldehyde by a formaldehyde-resistant bacterium isolated from seawater

A formaldehyde-tolerantbacterium designated as a DM-2 strain was used to biodegrade formaldehyde. The cells, precultivated in the presence of 400 ppm of formaldehyde, were able to degrade formaldehyde in a minimal medium supplemented with up to 400 ppm of formaldehyde in the presence of 3% NaCl. The rate of formaldehyde degradation achieved, in this study was 45 ppm/h when the DM-2 culture's optical density at 660 nm was 1.2.     

Reactivities of cellulases from fungi towards ribbon-type bacterial cellulose and band-shaped bacterial cellulose

We have investigated the reactivities of various cellulases onribbon-type bacterial cellulose (BC I) and band-shaped bacterial cellulose (BCII) so as to clarify the properties of different cellulases. BC I waseffectively hydrolyzed by exo-type cellulases from different fungi from twicetofour times as much as BC II, but endo-type cellulases showed little differencein reactivity on those substrates. One of the endo-type cellulases, EG II fromTrichoderma reesei, degraded BC II more rapidly thanexo-type cellulases even in the production of reducing sugars. The degree ofpolymerization (DP) of BC II was rapidly decreased by endo-type cellulases atanearly stage, while exo-type cellulases did not cause the decrease of DP atthe initial stage, though the decrease of DP was observed after an incubation of24 h. All exo-type cellulases adsorbed on BC I and BC II,whileendo-type cellulases except for EG II adsorbed slightly on both substrates. Itwas interesting to observe EG II adsorbed on BC I but not on BC II. It issuggested that the adsorption of enzyme on cellulose is important for thedegradation of BC I, but not for BC II. It is proposed that the ratio of aspecific activity of each enzyme between BC I and BC II represents thedifference in the mode of action of cellulase. Furthermore, the K _RW value, which we can calculate from thedecrease of DP/reducing sugar produced, is effective for discriminating themode of action of cellulase, especially the evaluation of randomness in thehydrolysis of cellulose by endo- and exo-type cellulases.     

Energy calibration of tagged photons by the d(γ,π~-pp) reaction

The energy of tagged photons, which were provided from the internal photon tagging system of the Laboratory of Nuclear Science, Tohoku University, has been calibrated using the d(γ,π-pp) reaction. Charged pions and protons in the final state were detected with the Neutral Kaon Spectrometer (NKS2). Photon energies were obtained from the reaction of d(γ,π-pp). The derived photon energy was consistent with the design of the tagger system and the previous measurement using electron-positron pair production. The consistency demonstrates the performance of NKS2 and the capability of the photon energy calibration using d(γ,π-pp).