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C Negishi

Publications and source records attributed to C Negishi.

41 records · Page 3Linked to original sources

Formation of 2-amino-3,7,8-trimethylimidazo [4,5-f]quinoxaline, a new mutagen, by heating a mixture of creatinine, glucose and glycine.

When a mixture of creatinine, glycine and glucose was heated for 2 h at 128 degrees C in diethylene glycol containing 14% water, two mutagens were formed. One of them, responsible for 90% of the mutagenicity, has already been identified as 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx). The other mutagen was purified and characterized. The UV absorption, mass and NMR spectra suggested that this mutagen was 2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline (7,8-DiMeIQx). Comparison of the spectral properties of the compound obtained from the heated model mixture with those of synthetic material confirmed this structure. 7,8-DiMeIQx is a newly identified compound which, at a dose of 1 microgram, induced 163 000 and 9900 revertants of Salmonella typhimurium TA98 and TA100, respectively, with S9 mix.

Chemical Phenomena↗

Spinal cord MRI in adult polyglucosan body disease.

MRI appearance of adult polyglucosan body disease is described. A 67-year-old man presenting with a chronic progressive degenerative neurologic disorder was found to have marked atrophy of the entire cord, without signal abnormalities on long TR images. Autopsy revealed atrophy of the cord, diffuse gliosis, and numerous corpora amylacea.

Aged↗

Fast spin-echo MR imaging of the cervical spine: influence of echo train length and echo spacing on image contrast and quality.

PURPOSE: To examine the interaction of echo train length and interecho spacing and their effects on image quality and contrast in fast spin-echo sequences of the cervical spine. METHODS: Forty-three patients with suspected cervical disk disease were prospectively evaluated with fast spin-echo with varying echo train lengths and interecho spacing. A flow phantom was used to confirm findings related to cerebrospinal fluid pulsation. Parameters were manipulated to adjust contrast, signal-to-noise ratio, the effects of artifacts, and the speed of acquisition. RESULTS: In general, increasing echo train length increased homogeneity and high intensity of cerebrospinal fluid signal and reduced acquisition time; however, it decreased the signal-to-noise ratio of cerebrospinal fluid and cord and increased blurring, and, to a lesser extent, edge enhancement, and "truncation-type" artifact. Increasing interecho space permitted the use of longer echo times but minimally decreased contrast and signal-to-noise ratio of cord and cerebrospinal fluid. In addition, increasing echo spacing increased blurring, edge enhancement, truncation-type, magnetic susceptibility, and motion artifacts. CONCLUSIONS: For cervical spine imaging, a long echo train length and short echo spacing partially compensate for cerebrospinal fluid flow and produce the best myelographic effect but must be modulated by other constraints, such as artifact production or technical capabilities.

Cervical Vertebrae↗

Vasculitis presenting as primary leptomeningeal enhancement with minimal parenchymal findings.

In this case of biopsy-proved granulomatous angiitis, MR showed prominent leptomeningeal enhancement with comparatively little parenchymal involvement. Pathologically, granulomatous angiitis chiefly affects small vessels, with a predilection for those in the leptomeninges. Although marked leptomeningeal enhancement is not the most common finding, vasculitis should be added to the differential diagnosis of this MR appearance.

Brain↗