Lack of mutagenic and co-mutagenic effects of magnetic fields during magnetic resonance imaging.

Mutagenic and co-mutagenic effects of static, pulsed bipolar gradient, and high-frequency magnetic fields, as well as combinations of them, were examined using the Ames test. The Ames test using Salmonella typhimurium bacteria, wild-type strain RTA, preincubation assay, without metabolic activation, was performed. All combinations of magnetic fields were tested with and without co-exposure to N-methyl-N'-nitro-N-nitrosoguanidine and benzo[a]pyrene-4,5-oxide, ethylene oxide, carboplatin, or cisplatin. As expected, chemical mutagens caused a clear-cut increase of the revertants in the Ames test. However, neither the static fields nor a combination of a static magnetic field with the time-varying bipolar gradient field or a pulsed high-frequency magnetic field caused an alteration in the number of revertants in the Ames test. No co-mutagenic effect of any magnetic field combination was observed. In conclusion, magnetic fields used during clinical magnetic resonance imaging (MRI) were neither mutagenic nor co-mutagenic.

Sensory neuropathy of the trigeminal, glossopharyngeal, and vagal nerves in Sjögren's syndrome.

Isolated cranial nerve involvement in primary Sjögren's syndrome (primary SS) has rarely been described. We report the case of a patient with sensory neuropathy of the trigeminal and also the glossopharyngeal and vagal nerves, which has not been identified previously. The electrophysiological findings in our patient with primary SS confirmed trigeminal sensory neuropathy with abnormal blink reflexes and abnormal cutaneous masseter inhibitory reflexes.

[Possible mutagenic effects of magnetic fields]. / Untersuchung eines möglichen mutagenen Potenzials von Magnetfeldern.

AIM: To assess the potential mutagenic effect of static magnetic fields of 1.5 T and 7 T, gradient fields and high frequency magnetic fields. METHOD: We used the Salmonella mutagenicity test (Ames test), which detects mutations in a gene of a histidine-requiring (his-) strain to produce a histidine-independent (his+) strain, Exposure to a static magnetic field of 1.5 T and 7.2 T, in a bipolar magnetic gradient and additionally in a high frequency field took place with and without known genotoxic chemicals. RESULTS: No differences in the number of revertants between the bacterial strains of exposed and control cells could be detected and the exposure with known genotoxic chemicals showed no significant difference in mutagenicity. CONCLUSION: In conclusion our data do not provide evidence that exposure to a static magnetic field exerts effects on the mutagenicity in our standard tester strains and whether the exposure took place in a diagnostic 1.5 T MR scanner which is used in the clinical routine or at 7.2 T which is a much stronger field made no difference. Also an exposure in a gradient field or in a high frequency field did not show any alteration in the number of revertants.