Chick embryos were exposed to sinusoidally oscillating 50 Hz magnetic fields during their first 2 days of development. In the first series of experiments magnetic field strengths of 0.1, 0.3, 1 and 10 A/m were used. The percentage of abnormal embryos (% AE) was 16 per cent in the sham-exposed control group. % AE was increased at 1 A/m (29 per cent) and 10 A/m (32 per cent), but not at 0.1 A/m (16 per cent) or 0.3 A/m (14 per cent). In the second series of experiments field strengths of 0.4, 0.6, 0.9 and 1.35 A/m were used. % AE was 17 per cent in the control group, 10 per cent at 0.4 A/m, 19 per cent at 0.6 A/m, 17 per cent at 0.9 A/m and 36 per cent at 1.35 A/m. Only the 1.35 A/m group was significantly different from the controls. The results of this study suggest that exposure of chick embryos to a 50 Hz magnetic field causes abnormal development, and that no abnormalities are induced below a threshold between 0.9 and 1 A/m.

Chick embryos were exposed during their 48 first hours of development to sinusoidally oscillating magnetic fields. The frequencies 1 Hz, 10 Hz, 16.7 Hz, 30 Hz, 50 Hz, 1 kHz, 10 kHz and 100 kHz, and the field strengths 0.1, 1, 10 and 100 A/m were used. Each exposure group consisted of 20 eggs. After the exposure, the embryos were examined for abnormalities and classified by the developmental stage. The percentage of abnormal embryos (%AE) was significantly increased at frequencies from 16.7 Hz to 100 kHz. Above a threshold field strength of about 0.1 to 1 A/m, %AE was rather independent of the field strength, varying from 16% to 56% in different exposure groups. 13% of the sham-exposed control embryos (n = 150) were abnormal. Only the 0.1 A/m exposure group differed significantly from the controls at 1 Hz, and no significant effect was found at 10 Hz. The developmental stage was in general not affected by the magnetic fields, but some abnormal embryos showed retarded development.

To evaluate the influence of antireflux surgery on gastric emptying.Design: Nonrandomized controlled trial 3 months before and after surgical intervention.Setting: Secondary and tertiary referral center.Patients and Control Subjects: Twenty consecutive patients (7 women, 13 men), mean age 49.2 years, with symptomatic, objectively confirmed gastroesophageal reflux disease and 10 healthy control subjects (3 women, 7 men), mean age 37.3 years. Intervention: Laparoscopic or open Nissen fundoplication (in 1 case Toupet 180°posterior hemifundoplication).Main Outcome Measures: Gastric emptying scintigraphy, using solid food, in control subjects and patients 3 months before and 3 months after the operation; time to halving of the maximal activity and the activity remaining at 60, 100, and 120 minutes.Results: Preoperative symptoms included pyrosis in 19 of 20 patients and regurgitation in 18. Three months postoperatively, 19 patients were symptom-free. The mean time to halving of the maximal activity decreased from 113 to 78 minutes (P = .001). Delayed gastric emptying was found postoperatively in 3 patients, compared with preoperative values, using activity at 60, 100, 120 minutes and the mean time to halving of the maximal activity as the variables. Compared with control subjects, gastric emptying was slower in patients preoperatively and faster postoperatively, but the difference was not statistically significant. Conclusion:Gastric emptying is enhanced after antireflux surgery, along with cessation of symptoms and healing of esophagitis.

Chick embryos were exposed during their 52 first hours of development to 100-Hz magnetic fields. Sinusoidal, square and pulsed waveforms were used at average field strengths from 0.1 A/m to 80 A/m. After exposure, the embryos were examined for abnormalities and classified by the developmental stages. When bipolar oscillations (oscillating at both sides of the zero-level) were used, the percentage of abnormal embryos was significantly increased above 1 A/m. In exposure to unipolar square waves, no significant effect on the percentage of abnormalities could be demonstrated. The developmental stage was possibly affected by unipolar square waves at 0.1 A/m, all other field strengths and waveforms being apparently ineffective.

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