Operation of a 400MHz NMR magnet using a (RE:Rare Earth)Ba2Cu3O7-x high-temperature superconducting coil: Towards an ultra-compact super-high field NMR spectrometer operated beyond 1GHz

High-temperature superconductors (HTS) are the key technology to achieve super-high magnetic field nuclear magnetic resonance (NMR) spectrometers with an operating frequency far beyond 1GHz (23.5T). (RE)Ba₂Cu₃O_7-x (REBCO, RE: rare earth) conductors have an advantage over Bi₂Sr₂Ca₂Cu₃O_10-x (Bi-2223) and Bi₂Sr₂CaCu₂O_8-x (Bi-2212) conductors in that they have very high tensile strengths and tolerate strong electromagnetic hoop stress, thereby having the potential to act as an ultra-compact super-high field NMR magnet. As a first step, we developed the world's first NMR magnet comprising an inner REBCO coil and outer low-temperature superconducting (LTS) coils. The magnet was successfully charged without degradation and mainly operated at 400MHz (9.39T). Technical problems for the NMR magnet due to screening current in the REBCO coil were clarified and solved as follows: (i) A remarkable temporal drift of the central magnetic field was suppressed by a current sweep reversal method utilizing ∼10% of the peak current. (ii) A Z2 field error harmonic of the main coil cannot be compensated by an outer correction coil and therefore an additional ferromagnetic shim was used. (iii) Large tesseral harmonics emerged that could not be corrected by cryoshim coils. Due to those harmonics, the resolution and sensitivity of NMR spectra are ten-fold lower than those for a conventional LTS NMR magnet. As a result, a HSQC spectrum could be achieved for a protein sample, while a NOESY spectrum could not be obtained. An ultra-compact 1.2GHz NMR magnet could be realized if we effectively take advantage of REBCO conductors, although this will require further research to suppress the effect of the screening current.

Pneumomediastinum is a frequent but minor complication during esophageal endoscopic submucosal dissection

BACKGROUND AND STUDY AIM

Esophageal perforation caused by endoscopic submucosal dissection (ESD) induces serious pneumomediastinum. In the absence of endoscopically detected perforation, postprocedural pneumomediastinum may occur. The aim of this study was to evaluate the association between the clinical factors/courses and pneumomediastinum revealed by chest computed tomography (CT) with special reference to an exposed muscle layer during esophageal ESD.

PATIENTS AND METHODS

A total of 58 patients undergoing ESD for esophageal neoplasms between February 2003 and June 2007 also underwent both chest radiography and chest CT within 1 hour after ESD. We studied the association between findings on CT scan and tumor-related and technical factors of esophageal ESD by uni- and multivariate analyses. We also analyzed the clinical factors/courses experienced by all patients.

RESULTS

Pneumomediastinum was detected in 18 / 58 patients (31 %) by chest CT compared with only 1 / 58 patients (1.7 %) by chest radiography. ESD-induced exposure of the muscular layer (32 patients) was the only significant factor for pneumomediastinum (18 / 32; P < 0.0001). Clinical factors such as fever, white blood cell count, and C-reactive protein were significantly increased in the group positive for both endoscopically exposed muscular layer and pneumomediastinum (+/+, n = 18) compared with the (-/-) group (n = 26) in the early phase (day 1) after ESD. However, these factors did not affect the length of the fasting period or the length of hospital stay.

CONCLUSIONS

In esophageal ESD, pneumomediastinum detected by chest CT only does not cause clinically significant complication. Endoscopic muscle exposure during ESD is a significant risk factor for pneumomediastinum, which causes mild inflammation in the early post-ESD phase.

Mer-A2026A and B, novel piericidins with vasodilating effect. II. Physico-chemical properties and chemical structures

The structure of vasodilating active substances, Mer-A2026A and B, produced by Streptomyces pactum Me2108 were determined on the basis of their spectral and chemical properties.

Mer-A2026A and B, novel piericidins with vasodilating effect. I. Producing organism, fermentation, isolation and biological properties

A strain of Streptomyces was found to produce new piericidins. The compounds were purified and separated into two substances named Mer-A2026A and B. These new piericidins exhibited vasodilating and depressor activities.

Synthesis of doxorubicin-cyclodextrin conjugates

Doxorubicin-gamma-cyclodextrin conjugates have been synthesized by the coupling of 14-bromodaunomycin with mono half-ester compounds linked to a 6-hydroxyl group of gamma-cyclodextrin. Release of drug from the conjugates in saline phosphate buffer solution and in vitro antitumor activity against L1210 leukemia cells were also investigated.

Enzymatic dimerization of penicillin X

Penicillin X methyl ester was transformed into three types of dimer by laccase from Coriolus versicolor. The dimers are considered to be formed by free-radical addition of phenoxy radicals produced by laccase. The enzyme reaction with the ester as substrate was more suitable for forming dimers than that with the sodium salt as substrate. Penicillin X pivaloyloxymethyl ester was also transformed into a dimer, which had antibacterial activity in the presence of esterase.