Allan H. Gobuty

Measurement of fetoplacental blood volume in the human previable fetus

Abstract Circulating fetoplacental blood volume (Vm) was measured in 19 previable human fetuses with 125 I-RISA. Fetal weight ranged from 130 to 464 grams and spanned a gestational age interval of six weeks. Mean Vm (±1 S.D.) was 16.2 ± 2.06 ml. per 100 grams of fetal weight. The increase in Vm appeared to be linear with increases in fetal weight.

A Kit for the Preparation of Basic 99mTc Penicillamine for Renal Scanning

Abstract A kit for preparing basic (pH 8.4) 99mTc-penicillamine complex for renal studies is described. The radiopharmaceutical prepared from the kit localizes in the kidneys, primarily in the renal cortex. Data is presented which demonstrates that the kit method for 99mTc-penicillamine results in biological distribution of the 99mTc-penicillamine complex equivalent to that observed for the older extemporaneous method of preparation. The per cent of injected dose localized in the kidneys of rabbits at one hour is 18.3 ± 3.1%, which compares favorably with other 99mTc-complexes used for renal imaging.

A new radioisotopic microassay of cell-mediated immunity utilizing technetium-99m labeled target cells.

Summary The 99mTc microcytotoxicity assay is a simple and sensitive means of assessing cell-mediated immunity in vitro. The short labeling time and high binding affinity of the nuclide are significant advantages over other radioisotopic assays which have been described. The short half-life is adequately compensated for by the high labeling efficiency and specific activity of the isotope. We thank Ms. K. Gollahon and L. Wickens for expert technical assistance and Ms. K. Phipps and L. Conaughton for secretarial assistance.

In Vivo Quantitation of Induced Ultrasonic Contrast Effects in the Mouse

The ability of certain aqueous solutions to enhance ultrasonic echogenicity from the intact mouse in vivo was examined. Substances which in solution increase the velocity of sound as a function of increasing concentration were found to intensify the “contrast” of whole mice visualized sonographically. Increase in contrast was determined by photometric measurement of the average integrated screen luminance of the area of the screen representing the mouse. The ability to enhance screen luminance correlated with the ratio of the slope of the change in speed of sound vs. concentration to the maximum non-lethal drug dose attainable, as determined by acute LD50 studies. Neither body temperature nor osmolarity changes appeared to be significant contributing factors in the enhancement of “contrast” produced by the agents tested. These results indicate that compounds with a high slope of the change of speed of sound vs. concentration in solution and with low toxicity can act in vivo as ultrasonic “contrast” agents when given systemically.