Radioactivity accumulation

The filters after Chernobyl accident were tested by Academy of Sciences and KGB of Ukraine on real water contaminated by radionucledes. Tables 4 and 5 illustrate typical results of water purification process and process of radioactivity accumulation by the filters, respectively. 

A few studies have been conducted on cannabis and its derivatives. Alozie et al. (3) measured the radioactivity accumulated in various brain areas following the intravenous injection of 3H-THC, 3H-cannabinol, and 3H-cannabidiol to adult male rats. Five minutes after injection, these three labeled compounds exhibited a homogeneous distribution in brain, suggesting that no specific binding occurred. Such studies must be completed by examining the time course of the evolution of 3H-cannabis derivatives in various brain areas before any firm conclusion can be drawn. 

This barrier can be further illustrated by comparing tissue insecticide ratios between the S and R populations. Radioactivity accumulated in major organs following exposure to 10 yg/1 l C-endrin is greater in S fish than in R fish for all organs studied except kidney (Table III). Similarly, S fish accumulate more aldrin, dieldrin and DDT in their brains than do R fish. 

With the exception of DDT, there was at least as much or more radioactivity accumulated in livers from S fish than in livers from R fish (Table IV). 

Table III - Radioactivity Accumulated in Tissues of Susceptible (S) and Resistant (R) Fish Exposed to 10 yg/1 licencin n for 6 hr...

The main modification for practical use in endocrine safety pharmacology is the application of this method to satellite groups of animals in a repeated dose study. Most pelleted animal feeds nowadays contain a standard amount of iodine (it may be useful to check the specification). Therefore, the addition of potassium iodine to the drinking water is not required. In this satellite groups, the animals are injected with a standard dose of radio-iodine after the last treatment, and the dose of radioactivity accumulated in the thyroid glands after a standard time interval (e.g. two hours) is determined and evaluated. 

It is important to identify the radioactive concentrations in soil because it constitutes a path for radioactivity to humans, animals and plants, and is an indicator of radioactive accumulation in the environment. Soil includes submarine sediment and river-bed soil,... 

The forest canopy is an effective filter for atmospheric pollutants due to high specific leaf area191-194. The importance of the forest ecosystem as the radioactivity accumulator... 

Twenty-four hours after oral administration of 28 pmol/kg of radioactive [methylene- C-]MBOCA to male Sprague-Dawley rats, the highest level of radioactivity was in the liver. The tissue distribution of total radiolabels (i.e., MBOCA plus its metabolites) was as follows liver > kidney > lung > spleen > urinary bladder > testes > brain > lymphocytes (Cheever et al. 1991). In another study, the distribution in female Wistar rats 24 hours after gavage with radioactive MBOCA was similar liver > intestine > lung > kidney > blood > stomach > spleen > uterus (Sabbioni and Neumann 1990). The remaining radioactivity was recovered in urine and feces. After 28 consecutive oral doses of radioactive MBOCA, the radioactivity accumulated more rapidly in the liver than in the blood (1,455 femtomoles/mg versus 122 femtomoles/mg tissue, respectively) (Cheever et al. 1991). The results show that, after either actue or intermediate oral administration, the highest amount of MBOCA and its metabolites accumulates in the liver. The results also show that after 28 doses, accumulation in the liver increased more than 100-fold. 

These PS based pharmaceuticals were also tested clinically, after obtaining informed consents of the volenteers and patients. These studies in man confirmed the findings obtained in rabbits. A scintigram obtained in a human subject is given as an example in Figure 2. Notice that only GI tract was visualized. Almost no radioactivity accumulation was detected outside of GIT. The ratio of GI tract/whole body was higher than 99%. ... 

When leaves were Incubated with [ C] 12 0, the C16 and C18 FA at both positions of eukaryotic and prokaryotic MGDG were labeled indicating access to the FA elongation system. In WT, declining radioactivity In 18 2/16 2 And 18 3/16 2 coincided with a rise in 18 3/16 3 showing progressive desaturation In the prokaryotic pathway (Fig. 2). In JBl, the 18/16C species were labeled more slowly and radioactivity accumulated in 18 2/16 2, Indicating Inhibition of these chloroplast desaturase(s). 

We have also quantified the effect of specific conjugate accumulation in the target area by comparing the quantity of radioactivity accumulated in normal and infarcted myocardium tissue after 5 hours and calculating an infarct-to-normal radioactivity ratio. This ratio depends on the degree of necrotization in each tissue sample and can vary between 5 and 50 for the labeled DTPA-PLL-Fab. At the same time, in case of routine DTPA-Fab preparations (direct labeling), the ratio even in the most necrotized samples is usually not higher than 1.5 to 3. 

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