Johns Hopkins University

Bios Corporation

Henry N Wagner

Robert H Wake

The effectiveness of drugs and substances that affect brain chemistry can be efficiently and relatively inexpensively monitored. Radioactive tracer substances comprising a ligand that binds to presynaptic or postsnaptic neuroreceptors is administered to a patient. Emissions (primarily positrons, and gamma rays which are emitted from the positrons) are measured. These emissions are indicative of the number and the degree of occupancy or blocking of the neuroreceptors. The number of neuroreceptors and the degree of occupancy or blocking is calculated utilizing a mathematical model, and compared with an intra-person or inter-person control, to determine the degree of drug response. Further treatment of the patient with drugs is based upon the comparisons made. Dopamine, serotonin, opiate, and other receptors all may be monitored, and the procedures are particularly applicable to treatment of Parkinson's disease, schizophenia, and drug addictions. Simple apparatus is utilized including a patient head support and first and second gamma ray directional detectors (such as NaI or BiGe detectors) disposed on opposite sides of the head support, and connected to circuitry including photomultiplier tubes, preamplifiers, and circuitry for correcting for random gamma ray detections.

Neuroreceptor activity assessment

The effectiveness of drugs and substances that affect brain chemistry can be efficiently and relatively inexpensively monitored. Radioactive tracer substances comprising a ligand that binds to presynaptic or postsynaptic neuroreceptors is administered to a patient. Emissions (primarily positrons, and gamma rays which are emitted from the positrons) are measured. These emissions are indicative of the number and the degree of occupancy or blocking of the neuroreceptors. The number of neuroreceptors and the degree of occupancy or blocking is calculated utilizing a mathematical model, and compared with an intra-person or inter-person control, to determine the degree of drug response. Further treatment of the patient with drugs is based upon the comparisons made. Dopamine, serotonin, opiate, and other receptors all may be monitored, and the procedures are particularly applicable to treatment of Parkinson's disease, schizophenia, and drug addictions. Simple apparatus is utilized including a patient head support and first and second gamma ray directional detectors (such as NaI or BiGe detectors) disposed on opposite sides of the head support, and connected to circuitry including photomultiplier tubes, preamplifiers, and circuitry for correcting for random gamma ray detections.

A built up image illustrating blood volume in the heart versus time taken over many cardiac cycles is produced by continuously displaying a graph of cumulative data indicating the amount of radioactivity from a tracer in the blood detected in the heart during each of a series of intervals into which the average cardiac period is divided. The parallel lines of a raster scan display correspond respectively to the memory channels. The count stored in a particular memory channel causes the video signal for the corresponding line to be maintained at a binary level for a corresponding time interval thus generating a bar graph in which the length of each bar indicates the amount of radioactivity sensed during the corresponding interval of the cardiac cycle. As each memory channel accumulates radioactivity data with each successive cardiac cycle, each bar displayed in the bar graph lengthens to indicate the cumulative activity until an interpretable curve is obtained.

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Baltimore, MD, United States of America

Henry N Wagner