Low-level EMFs are transduced like other stimuli.

The aims of this study were to test the theory that transduction of low-level electromagnetic fields (EMFs) is mediated like other stimuli, and to determine the false-negative rate of the method used to assess the occurrence of transduction (intra-subject comparison of stimulus and non-stimulus states (ICOS)). A light stimulus was chosen as a basis of comparison because light could be applied and removed at precise time points, similar to the manner in which EMFs were controlled. Subjects exposed to a weak light stimulus during 2-second epochs exhibited alterations in brain electrical activity that were similar to those previously observed in subjects exposed to EMFs. The false-negative rate of the ICOS method was 61%, since it registered an effect in only 39% of the subjects (11/28) whereas all subjects were actually aware of the light. In a second group of subjects that were exposed to 0.8 G (1.5 or 10 Hz), 58% (11/19) exhibited similar alterations in brain activity, as determined using ICOS. Previous measurements in the same subjects using a different method showed that the EMFs actually affected brain electrical activity in all subjects; consequently, the false-negative rate was 42% when an EMF was used as the stimulus. The results suggested that the post-transduction brain electrical processes in human subjects were similar in the cases of EMF and light stimuli, as hypothesized, and that the high negative rate of the ICOS method (here and in previous studies) was composed partly or entirely of false-negative results.

Frequency-specific responses in the human brain caused by electromagnetic fields.

The effects of 1.5- and 10-Hz electromagnetic fields (EMFs), 0.2-0.4 gauss, on the intrinsic electrical activity of the human brain at these frequencies was studied. Each of 19 subjects exposed for 2-sec epochs exhibited altered brain electrical activity at the frequency of the EMF during the time of stimulation, as determined by spectral analysis of the electroencephalogram. Since brain activity at specific frequencies could be altered by applied EMFs, the results suggest that it may be possible to use EMFs to determine whether particular intrinsic frequencies subserve specific physiological or behavioral responses.

Frequency-specific blocking in the human brain caused by electromagnetic fields.

Based on preliminary observations that continuous exposure to electromagnetic fields (EMFs) produced an after-effect on human brain electrical activity, the effect of 10 Hz, 1 gauss, on the intrinsic activity of the brain at that frequency was studied. Ten subjects were exposed for 10 min and the 10 Hz spectral power was measured during the 1 min interval following stimulation and compared with control values obtained from the same subjects. Significantly reduced brain electrical activity from the occipital electrodes following termination of the EMF exposure was observed, thereby confirming the preliminary results.

Alterations in brain electrical activity caused by magnetic fields: detecting the detection process.

Static and 60 Hz magnetic fields, 0.78 gauss, were applied individually and combined to each of 20 human subjects during 2 sec epochs, and the effect on the EEG was determined by comparing the power spectrum obtained during field exposure with that from control epochs. All but one subject exhibited field-induced alterations in the EEG; most subjects exhibited increased EEG activity at 2 or more frequencies within 1-18.5 Hz. The field-induced changes were recorded more often at the central and parietal electrodes than at the occipital electrodes. The responses observed during application of combined static and alternating fields did not differ from the sum of the responses observed when the fields were applied individually, even though the exposure conditions were specifically chosen to favor the hypothesized ion-resonance mechanism of interaction involving Ca2+. The data support the view that detection loci for magnetic fields exist within the nervous system.

Cimetidine and ranitidine in duodenal ulcer.

Two histamine H2 antagonists, cimetidine and ranitidine, given in doses of 1 g daily and 200 mg daily to 18 and 20 patients respectively proved equivalent in promoting healing of duodenal ulcer. No adverse effects occurred during the trial, though serum urea and creatinine concentrations tended to rise slightly during treatment with cimetidine but not ranitidine. Choice between the two drugs is likely to be influenced by overall patterns of adverse effects rather than considerations of individual potency.

A new constant infusion radioisotopic technique for the noninvasive determination of cardiac output.

A constant infusion radioisotopic method for the noninvasive determination of cardiac output is introduced and validated in a series of 22 patients by comparison with simultaneous dye dilution or Fick measurements. The new bedside radioisotopic technique utilizes peripheral venous infusion of indium-113m, detection by a single external probe, and analysis of the time-concentration curve by a specially designed, multivariate computer model. The technique is entirely atraumatic, requiring neither injection into the central circulation nor intra-arterial cannulation. The correlation coefficient was 0.72 (p less than 0.001) between the radioisotopic and standard methods for cardiac output determinations. In addition, results in five patients with valvular regurgitation or intracardiac shunts support the validity of the constant infusion radioisotopic technique in these clinical settings in which the standard dye dilution methods for determining cardiac output are invalid. The techniques is applicable in a variety of clinical conditions in which the invasive techniques for cardiac output measurement are either impractical or not available.

Diagnosis of cirrhosis and hepatitis by quantitative hepatic and other reticuloendothelial clearance rates.

Although methods for measuring colloid clearance rates have been described, they are not commonly used. Rather, most clinicians rely on the relative radiocolloid accummulation in the liver and spleen as estimated by visual inspection of liver scans. This method lacks objectivity, however, and only indirectly reflects the rate of radiocolloid clearance. We have developed a noninvasive kinetic technique for measuring radiocolloid clearance by the liver, spleen, and other reticuloendothelial tissues. The clerance-rate constants obtained by this technique appear to differentiate among cirrhosis, fatty metamorphosis, hepatitis, and normal function. In normal subjects, the mean clearance-rate constants for the liver, spleen, and extrahepatosplenic reticuloendothelial system were 16.0, 1.4, and 3.4 ml/min per 100 ml of plasma, respectively. The mean hepatic clearance-rate constant was normal in hepatitis (16.8 ml/min per 100 ml), reduced in cirrhosis (5.7), and slightly reduced in fatty metamorphosis (10.4). Both the hepatic-to-splenic and the hepatic-to-extrahepatosplenic ratios of clearance-rate constants were reduced in cirrhosis and slightly reduced in fatty metamorphosis and hepatitis. Interestingly, the splenic clearance-rate constants were normal in these three diseases.