Biomedical subjects
Publications and source records attributed to C Yamanaka.
TM110 mode and TE111 mode ESR microwave cavities for in vivo human tooth dosimetry are developed. ESR signal from a sample is measured by using microwave leak from the pin hole on the cavity wall. The minimum detectable dose of 2 Gy is obtained by the signal accumulation for 100 sweeps.
A case of overexposure of an industrial radiographer using 192Ir sources and having a filmbadge dosimeter record of 104 mSv has been examined with ESR dosimetry of postmortem tooth and bone specimens. ESR measurements of the tooth enamel showed an intense signal of CO2- and gave the equivalent dose (ED) of 14 Gy by the additive dose method using gamma-rays from a source of 60Co. The doses for a finger bone and humerus were 14.7 and 7.0 Gy, respectively. It was concluded that he had been exposed to radiation repeatedly over 10 yr and that ESR dosimetry can give a life-long cumulative dose for personnel using radiation.
Valproate (VPA) induces zinc (Zn) deficiency in experimental animals, but whether VPA treatment induces deterioration of serum trace metal homeostasis in humans is uncertain. We measured serum copper (Cu) and Zn levels in epileptic children treated with VPA and/or other antiepileptic drugs (AEDs). Patients treated with VPA monotherapy had significantly lower levels of serum Cu (82.2 +/- 16.6 micrograms/dl) than normal controls (97.3 +/- 23.0 micrograms/dl). Patients treated with VPA in addition to some other AED also had significantly lower levels of serum Cu (84.8 +/- 20.0 micrograms/dl). Serum Cu concentrations in patients treated with AEDs except for VPA (87.7 +/- 19.1 micrograms/dl) were not statistically different from those of control subjects. In contrast to the reported results of animal experiments, serum Zn levels were not altered in patients with VPA treatment. Although none of our patients showed any symptoms of Cu deficiency, we should pay attention to potential Cu deficiency in patients with VPA treatment.