Comparison of several methods for the measurement of urinary hippuric acid as an index of toluene exposure.

The levels of hippuric acid in the urine of people exposed to toluene vapour were measured by paper chromatography, direct colorimetry, high performance liquid chromatography and gas chromatography. The control was a similar group not exposed to toluene vapour. The values were analyzed statistically, conversion equations calculated, and the propriety of these equation discussed. Since the three chromatographic methods gave similar values, the measurement of urinary hippuric acid by these methods can be used as an index of toluene exposure. The colorimetric method gave higher levels the chromatographic methods, especially for the urine of people not exposed to toluene. This may have been due to glycine conjugates (other than hippuric acid) developing a similar color, resulting in elevated values for hippuric acid. This colorimetric method should be used with caution for biological evaluation of workers with low toluene exposure.

[Diagnostic evaluation on cerebral hemisphere scintigraphy using 99mTc-MAA (author's transl)].

Using 99mTc-labeled macroaggregated albumin (99mTc-MAA), we made an examination of the cerebral blood flow distribution with various kinds of cerebrovascular diseases in 151 cases. The particle size of MAA used in this study ranged from 10 to 100 micron. Scan was performed after injection of 3 mCi of 99mTc-MAA into common carotid artery. No side effects were observed except for one case with headache. Distribution of 99mTc-MAA was found to be homogeneous in normal cerebral hemisphere but not in the lesion. Most lesion was shown as nonradioactive area. Meningioma with hypervascularity was represented as hot area. By this method cerebral infarct could be easily represented not only in main artery but also in such a very small artery as hardly detected by CAG. This method is therefore useful for detecting cerebral infarct, sequela of cerebral apoplexy, head injury and others. The dose of 99mTc-MAA used in this method is much lower compared with those of common brain scan, its excretion is speedy, and therefore internal radiation exposure is diminished.