PLACENTAL TRANSFERS: MODERN METHODS OF STUDY
Advantages and disadvantages in the use of radioisotopes in the study of placental permeability are presented. The study of placenital permeability with radioisotopes is discussed in terms of three categories: quantitative studies: what is transferred; quantitative studies: how much is transferred and how fast does it pass; localization studies: wwhere and how does it cross the placental barrier; advantages of various half-life times and types of radiation are also dealt with. Experimental results obtained with the following isotopes are reviewed: D, C/sup 14/, F/sup 18/, Na/sup 22/, Na/sup 24/ S/sup 35/, K/sup 42/, Ca/sup 45/, Cr/sup 51/, Fe/sup 59/, Co/sup 60/, Zn/sup 65/ , Br/sup 82/, Kr/sup 85/, Rb/sup 86/, Sr/sup 89/, Mo/sup 99/, Ru/sup 105/, I/sup 125/, I/sup 131/, I/ sup 132/, Ba/sup 133/, Cs/sup 137/, Ce/sup 144/, Po/sup 210/, Rn/sup 221/, Ra/sup 226/, and Pu/sup 239/. Placental transfer and the fetal uptake of the commonly found radioactive contaminants oi the environment are also discussed. These include radioactive elements detected in air or water pollution, those produced by fission of U/sup 235/, or those rendered radioactive by the neutrons released after fission. The placental membrane is able to discriminate between some periodic relatives, which may be an additionial mechanism of protection for the fetus. Another group of radioactive contaminants, belonging to the family of rare earths, behave as colloids and are withdrawn from circulation by the mother, even before they reach the placenta. Radioactive elements which can cross the placental barrier damage fetal tissues according to their respective metabolic role o to their. affinity for nonmetabolites. The amount of Sr/sup 90/ transferred during pregnancy is negligible compared to that taken up by the newborn, The present concentration of tritiated water in the biosphere is negligible from the point of view of radiation damage. The possible influence of an increased C/sup 14/ level is still a matter of controversy, but a further increase could lead to a parallel increase of genetic damage. (BBB)
- Research Organization:
- Univ. of Montreal
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-18-001345
- OSTI ID:
- 4152048
- Journal Information:
- American Journal of Obstetrics and Gynecology (U.S.), Vol. Vol: 84; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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ACTIVATION
AGE
AIR
BARIUM 133
BLOOD CIRCULATION
BROMINE 82
CALCIUM 45
CARBON 14
CERIUM 144
CESIUM 137
CHROMIUM 51
COBALT 60
COLLOIDS
CONTAMINATION
DETECTION
DEUTERIUM
DIFFUSION
ENVIRONMENT
FETUSES
FISSION PRODUCTS
FLUORINE 18
GENETICS
HALF-LIFE
HEAVY WATER
IODINE 125
IODINE 131
IODINE 132
IRON 59
KRYPTON 85
MEMBRANES
METABOLISM
MOLYBDENUM 99
NEUTRONS
PLACENTA
PLUTONIUM 239
POLONIUM 210
POTASSIUM 42
PREGNANCY
QUANTITY RATIO
RADIATION DOSES
RADIATION EFFECTS
RADIATION INJURIES
RADIATIONS
RADIOISOTOPES
RADIUM 226
RADON 222
RARE EARTHS
RUBIDIUM 86
RUTHENIUM 105
SODIUM 22
SODIUM 24
STRONTIUM 89
S